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                             culture
A time to live...




                                  Jumping for joy

                  Sierra Leone is a country on the west coast of Africa with a population of
                  some 3,600,000. It takes its name ("Lion mountain") from that given by
                  the Portuguese explorer Pedro da Sintra around 1460 to the peninsula
                  which is the site of Freetown, the country's capital. In 1787 a settlement
                  for freed slaves was established on land where Freetown now stands. In

                  1961 Sierra Leone achieved independence, and ten years later became a
                  republic. Some 65 per cent of the work force is occupied in agriculture,
                  with rice as the main food crop. Sierra Leone is the world's sixth largest
                  producer of diamonds. Above, body bent back and almost obscuring the
                  ball, a boy throws himself into a game of soccer in a Freetown street.




52 Sierra Leone
Editorial                                                                                             March 1987
                                                                                                      40th year


In the 1960s and 1970s, the development of high-yield cereal varieties                                 4

combined with the use of pesticides , irrigation and fertilizer brought a                              The new biotechnologies
Green Revolution to some               but not all     parts of the Third World. This                  Promise and performance
                                                                                                       by Jacques C. Senez
issue of the Unesco Courier, which is largely devoted to the application of
new scientific techniques to agriculture, enquires into the extent to which
the Green Revolution is likely to be followed by a "Biotechnological                                   The Green Revolution

Revolution" which may help developing countries to solve some of their
                                                                                                       13
food production problems.
  Although the term biotechnology to denote the use of the biochemical                                 The gene revolution
                                                                                                       by Bernard Dixon
and genetic capacities of living organisms for practical purposes is fairly
                                                                                                       17
new, man has been engaged in "biotechnological" activities since very
early times. Fermentation and the improvement of useful plant and                                      Tomatomation

animal varieties by cross-breeding are but two examples. The new                                      Japan's high-tech food factories
                                                                                                      by Koichibara Hiroshi
biotechnology, however, differs from these time-honoured practices in
                                                                                                       20
that it uses genetic engineering and techniques of fusing cells of different
organisms to surmount previously impassable barriers between species.                                  Hybrids for the year 2000
Genetic engineering (or gene-splicing) , which involves the direct transfer                            by Raissa G. Butenko and Zlata B. Shamina

of genes       "those tiny command posts of heredity that tell living cells                            22

whether they will become bacteria, toads or men"                    into the cells of                  Grains of hope
different species has been described as the "most powerful and awesome                                 by Edward C. Wolf
skill acquired by man since the splitting of the atom . "                                              24

  In the first part of this issue we look closely at some of these new
                                                                                                       The rediscovery of traditional
biotechnologies: how they work; how they are currently being used in
                                                                                                       agriculture
different parts of the world and to what effect; the latest trends in this
                                                                                                       26
field where changes occur quickly and possibilities are vast. While our
contributors focus mainly on the direct applications of biotechnologies to                             Rusitec the cow
                                                                                                       Food for rumination
agriculture in the developing world, they also note present and potential
uses in energy production, human and animal medicine and the                                           27

management of certain environmental problems.                                                          Rhizobium, the farmer's Mr. Fixit
  The second part of the issue asks broader questions. How can the new                                A Unesco programme to promote
                                                                                                      biotechnology for development
biotechnologies be best harnessed to development in different social ,
                                                                                                      by Edgar J. DaSilva, J. Freiré, A. Hillali
economic and cultural contexts? Will they be a panacea or, contrariwise,                              and S.O. Keya
are they likely to aggravate existing disparities between developing                                   29
countries and those of the technologically advanced world? The new
                                                                                                       A challenge for the developing world
biotechnologies and especially those applied to plants, put great
                                                                                                       by Albert Sasson
possibilities into the hands of those who control them. How should this
                                                                                                       34
power best be exercised? How should access to the fruits of research
based on plant genetic resources originating in the developing world be                                Glossary
equitably organized?                                                                                   2

   Unesco, which is engaged in worldwide efforts to strengthen rural
                                                                                                       A time to live...
development through training in the biological and agrobiological                                      SIERRA LEONE: Jumping for joy
sciences, in applied microbiology and in biotechnology (see article page
27) , is closely interested in the above issues as part of its basic
commitment to promote the use of science and technology for the benefit
of all humanity. The complex nature of the problems and some possible
approaches and solutions are traced by Dr. Albert Sasson in the article
which forms the conclusion of this issue.




Editor-in-chief: Edouard Glissant                                                                     Cover: Photo © Periscoop, Paris




                                                            Italian        Turkish       Macedonian                       A selection in Braille is
The Courier                                   English
                                              French        Hindi          Urdu          Serbo-Croat
                                                                                                            Finnish

                                                                                                            Swedish       published quarterly in English,
A window open on the world                                                                                                French, Spanish and Korean
                                              Spanish       Tamil          Catalan       Slovene            Basque
Published monthly in 32 languages             Russian       Hebrew         Malaysian     Chinese            Thai
by Unesco
                                              German        Persian        Korean        Bulgarian
The United Nations Educational,
                                              Arabic        Dutch          Swahili       Greek
Scientific and Cultural Organization                                                                                      ISSN 004 1-5278

7, Place dc Fontenoy, 75700 Paris.            Japanese      Portuguese     Croato-Serb   Sinhala                          N"3-1987-CPD-87-l-443 A
by Jacques C. Senez




            The new

                                        biotechnologies
                            Promise and performance


SINCE the beginnings of civilization,             hopes, some of which, such as the produc¬          sugar is another example of a social and
       man has been a biotechnologist, tak¬       tion of human insulin by bacteria recom-           economic backlash due to biotechnology.
       ing advantage of the activities of         bined in vitro, have already become reality.       Due largely to the production of iso-glucose
micro-organisms of whose very existence he        Today, these methods are on the verge of           in the United States, this sugar price col¬
was unaware, to produce foodstuffs and fer¬       finding new applications of considerable           lapse has spelled ruin to a number of tropi¬
mented drinks. Over the centuries, the            economic and social importance in the field        cal countries whose economies are based on

practices by which he did this gradually          of agriculture. It would be wrong, however,        sugar-cane.
developed, in a makeshift, empirical fash¬        to think that the prospects for biotechnol¬          Fortunately,      not    all   biotechnology
ion, to attain a high degree of perfection.       ogy are limited to the field of genetic engi¬      applications entail problems such as these.
Yet biotechnology proper, in the sense of         neering. Recent advances in fundamental            However, there is a danger that some of
the scientific use of biological principles for    knowledge and techniques in the physiol¬          them    will   further   increase   rather   than

practical purposes, only emerged at the end       ogy of cells, biochemistry, enzyme catalysis       diminish Third World dependence on the
of the last century with the birth of micro¬      and bioengineering are just as promising.          richest and most scientifically advanced
biology and its early application to indus¬          It is generally thought that there is a great   countries (see article page 29).
trial fermentation processes.                     future for biotechnology in the developing           Bearing this in mind, the developing
  Since the Second World War, biology has         countries, particularly in its applications to     countries must concentrate their efforts on
made prodigious progress. In just a few           agriculture. These hopes are well founded,         programmes which are both of direct inter¬
years the basic mechanisms of life and            but it should not be forgotten that progress       est to them and which can be implemented
heredity at the molecular level have been         involves potential dangers against which all       immediately within the limitations of their
unveiled, thus opening up limitless hori¬         possible preventive measures should be             financial and economic resources. Many
zons. Some of these prospects, in particular      taken.
                                                                                                     such opportunities are open to them in agri¬
that of the development of genetic engi¬             The first major achievement of agri¬            culture in which two avenues in particular
neering (see article page 13) with its con¬       cultural biotechnology was the "Green              beckon: that of primary production, where
notations of man the creator, captured the        Revolution", whose ambitious objectives            there are possibilities in the field of plant
imagination and fired the enthusiasm of the       have been largely achieved (see box page           improvement and nitrogen fixation, and
general public.                                   7). Thanks to the Green Revolution India,          that of bioconversion of agricultural prod¬
  The transfer of genetic material between        Bangladesh and several other Third World           ucts and wastes into energy and food
organisms as widely different as bacteria,        countries have achieved self-sufficiency in        resources.

plants, animals and man gave rise to great        food. This was a true success, but it brought
                                                  in its train a number of unforeseen social
                                                                                                             New techniques
                                                  consequences. The farming of high-yield
                                                                                                             for better plants
                                                  cereals requires considerable investment in
                                                  fertilizers, pesticides and irrigation which       Plant improvement by the traditional
                                                  many small farmers were unable to make.            methods of selection and cross-breeding is
                                                  As a result many of them had their fields          as old as agriculture itself. Thanks to recent
                                                  taken over by the large landowners and             advances in knowledge of the genetics and
                                                  were forced to move to the cities and swell        physiology of plants these methods have
                                                  the ranks of the sub-proletariat.                  been refined and will long continue to pro¬
                                                     The recent collapse in the world price of       duce very important results. During the
                                                                                                     past thirty years, for example, the yield of
                                                                                                     maize has increased from 12 to 62 quintals
                                                                                                     per hectare, while that of wheat has grown
                                                  Egyptian      bakers and brewers of 3,500
                                                                                                     on average by one quintal per hectare per
                                                  years ago are shown at work in this scene
                                                                                                     year. Similar progress has been made with
                                                  from a Theban tomb. "Biotechnological"
                                                  processes such as microbial fermenta¬              rice, the second most important of the great
                                                  tions have been used for thousands of              cereals in worldwide use. Today, the Inter¬
                                                  years to produce beverages and foods               national Rice Research Institute (IRRI),
                                                  such as beer and cheese.                                                                               <
                                                                                                     set up in the Philippines in 1962, has a col¬
                                                                                                                                                         ©

                                                  Drawing taken from A History of Technology         lection of 60,000 varieties of rice (see the
                                                  © Oxford University Press                          Unesco Courier, December 1984).
Drawing shows in highly simplified form
                                                                                                         one of the techniques used in modem
                                                                                                         biotechnology for experimentation under
                                                                                                         controlled conditions with plant cells, tis¬
                                                                                                         sues and organs and for vegetative (i.e.
                                                                                                         non-sexual) propagation of plants in ster¬
                                                                                                         ile laboratory conditions. The sterilized
                                                                                                         plant material which is cultured in the nut¬
                                                                                                         rient medium may be a meristem (see
                                                                                                         drawing at bottom of page), or some other
                                                                                                         piece of plant tissue (see photo story
                                                                                                         pages 8-9), or a protoplast, a plant cell
                                                                                                         whose   outer    walls   have   been    removed
plant     culture of           colony of                 regeneration            mini- greenhouse        (see page 10). From this organ, tissue, or
          meristem or          cells                     of plantlets
          cells
                                                                                                         protoplast, a proliferating clump of dis¬
                               multiplication
                                                                                                         organized tissue called a callus can be
                               in sterile
                                                                                                         obtained. From this it is possible to re¬
                               conditions
                                                                                                         generate whole intact plants, and to pro¬
                                                                                                         duce many genetically identical copies,
                                                                                                         known as clones, in a relatively short time.
                                                                                                         A one-cubic-centimetre culture may con¬
 In addition to improving yield, the main             culture of the meristem or other plant             tain one million cells each carrying the
purpose of selection is to obtain new vari¬           tissues. Meristem is the name given to a           potential of becoming an entire new plant.
eties which are resistant to parasites and to         grouping of embryonic cells situated at the        By selecting cells with certain properties,
                                                                                                         the process of breeding new varieties of
bacterial and viral diseases. In recent years         tip of the plant stem (see drawing below).
                                                                                                         disease-resistant, stress-tolerant crops,
a number of new techniques have made                  Cultivated in aseptic conditions on a solid,
                                                                                                         trees or flowers can be greatly
their appearance,       some   of which         are   nutritive    culture   medium,    these    cells   accelerated.
already in use while others are still at the          proliferate producing a callus which can be
laboratory stage. One of their main aims is           divided     and   reproduced     many     times.
to reduce considerably the time needed for            Treated with      plant   hormones      (auxins,
a new variety to be put on the market and             cytokins and gibberelins), the calluses diffe¬     months, 2,000 million identical tubers,
brought into large-scale cultivation. Using           rentiate into plantlets having all the prop¬       spread over an area of 40 hectares, were
classic methods the lead time required to             erties of the original plant.                      obtained from a single potato tuber derived
achieve this is of the order of ten years,              By this means, in a period of eight              from a meristem, that is a rate of propaga¬
whereas, given the capacity for adaptation                                                               tion 100,000 times greater than that of sex¬
of the phytopathogenic agents (the bacte¬                                                                ual reproduction. A further advantage is
ria, viruses, etc., that cause plant disease),                                                           that plants obtained from meristems are
the useful life of a new variety is estimated         The apical meristem is a tiny mass of cells
                                                                                                         free of pathogenic contaminants, in particu¬
                                                      where growth takes place at the tip of a
to be a mere five years.                                                                                 lar of viruses, which means that it is possible
                                                      plant stem. It plays a particularly important
  Another advantage of certain recently               role in plant propagation because it re¬           to regenerate stock threatened with extinc¬
evolved techniques is that they make it pos¬          mains healthy even when the rest of the            tion due to diseases that cannot be treated

sible to cross-breed species that are too far         plant is infected with a virus. In vitro cul¬      in any other way.
apart for normal sexual reproduction, thus            ture of the meristem of a diseased speci¬            Tropical agriculture has much to gain
                                                      men makes it possible to generate a new,
opening the way for the creation of entirely                                                             from micro-propagation. For example, a
                                                      healthy plant, and allows the rapid produc¬
new plant varieties.                                                                                     single oil palm regenerated from a fragment
                                                      tion of virus-free planting materials. Be¬
  The first major successes were achieved             low, sectional drawing of a plant bud              of leaf tissue could, within a year, supply
by means of vegetative hybridization of               shows the apical meristem at centre, pro¬          500,000 identical, filariosis-resistant plants
cereal seedlings. This method, which con¬             tected by enfolding leaf shoots. Meristem          producing up to 6 tonnes of oil per hectare
sists of cross-breeding between plants by             culture calls for particular care in the           per year, that is six to thirty times more than
                                                      choice of culture conditions and nutritive
the elimination of self-fertilization, is com¬                                                           the principal oil-producing plants (sun¬
                                                      media.
paratively easy in the case of allogamous                                                                flower, soya, peanut). This same technique
cereals, such as maize, in which the male                                                                is now being applied to the propagation of
                                                                                        leaf shoots
organs are separated from the female                                                                     new varieties of coconut palms.
organs and can thus be manually eliminated                                                                 Another technique which holds great
before fertilization has taken place. It is                                                              promise for the future is the in vitro produc¬
more difficult with autogamous plants, such                                                              tion of haploid plants (plants whose cells
as wheat, tomatoes, soya and lupin, in                                                                   contain a single set of chromosomes). Tra¬
which the male and the female organs are                                                                 ditional   methods   of selection      are   made

contained in close proximity within the                                                                  more    time-consuming and        complicated
flower. Today, this difficulty has been over¬                                                            because of the diploid nature of vegetative
come by the discovery of chemical com¬                                                                   plants, that is to say, because the cells of
pounds which render the pollen sterile.                                                                  which they consist contain a double set of
  Many varieties of hybrid cereals and                                                                   chromosomes, one coming from each pa¬
other plants are now on the market. Gener¬                                                               rent. As a result, some so-called "recessive"
ally speaking, fields should be sown with                                                                characteristics carried by a chromosome
first generation hybrid seed. Hybrid seed                                                                may be masked by a dominant homologous
usually tends to degenerate and must be                                                                  chromosome and its presence may only
renewed annually. At all events, the world                                                               be revealed, through the operation of
market for hybrid seed is growing rapidly                                                                Mendelian       segregation,    after    several
and, according to a recent estimate, will                                                                generations.
attain a value of $20,000 million by the year                                                              This, of course, slows down the work of
2000.
                                                                                                         the person undertaking the selection. The
  Other techniques now being developed                                                                   recent emergence of a technique somewhat
are more distant in prospect yet just as                                                                 similar to micro-propagation has made it
promising. One of these is in vitro vegetative                                                           possible to overcome this difficulty. This
propagation, or micro-propagation, by the                                                                technique enables a complete plant to be
obtained either from the male gametes, or           in regenerating somatic hybrid cells of sev¬                 Nitrogen fixation
reproductive cells (androgenesis), or from          eral plants of agricultural interest such as
the female gametes (gynogenesis). Like the          rapeseed, chicory and potato. On the other          Through its World Network of Micro¬
gametes from which they are derived, these          hand, attempts to do the same with sun¬             biological Resources Centres (MIRCENs),
plants are haploid. Since they have only one        flower, cereals and legumes have so far             one of whose priority programmes is
set of chromosomes, their genetic charac¬           failed. Nevertheless, there is hope that            devoted to the question of nitrogen fixa¬
teristics, whether recessive or dominant,           present difficulties will soon be overcome,         tion, Unesco is contributing actively to
are immediately evident to the person mak¬          at least in obtaining hybrids of varieties of       another field of biotechnology that is rich in
ing the selection. Haploid plants are usually       the same species.                                   promise (see article page 27).
infertile, but by treating them with col¬             The great advantage of somatic hybrid¬              The nif genes, which are coded for the
chicine, which induces a doubling of the            ization is that it makes it possible to transfer    fixation of nitrogen, have now been identi¬
chromosomes, a fertile plant is obtained            not only the genetic characteristics borne by       fied and their structure is on the point of
with two sets of identical chromosomes and          the chromosomes of the nucleus, but also            being fully mapped out. Furthermore, these
with phenotypically stable characteristics.         those of the specialized parts of the cell          genes     have     been     transmitted       to    non-
Another technique used in gynogenesis is to         contained in the cytoplasm (the "liquid"            nitrogen-fixing organisms such as Proteus
fertilize the ovule with irradiated pollen.         portion of a cell surrounding the nucleus)          vulgaris, Agrobacterium tumefaciens and
  In China, new varieties of rice obtained          such as mitochondria and chloroplasts.              Escherichia coli. In principle there is no
by androgenesis are being cultivated on sev¬        These latter are the key to processes and           reason why they should not also be trans¬
eral millions of hectares of land. Laboratory       properties of great importance such as              ferred to higher plants and important
experiments in gynogenesis are also now             photosynthesis, the assimilation of carbon          results in this direction can be expected
being undertaken on barley, rice, wheat,            dioxide, male sterility and resistance to           soon. However, the creation of nitrogen-
maize, sugar-beet and other species.                herbicides, diseases and drought.                   fixing cereals is a distant prospect still in the
                                                      Somatic hybridization has paved the way           realm of science fiction.
  High hopes are also being placed in soma¬
tic hybridization, a technique which consists       for the newly emerging discipline of plant             With regard to plants other than the
of fusing two cells whose cell walls have           genetic engineering which is concerned with         legumes, attention is now concentrated on
previously been removed by enzymatic                the implantation of specific genes", whether        nitrogen fixation by bacteria and fungi
treatment. Using this technique scientists          of vegetal or other origin, into the genetic        which invade their roots either on the root

have succeeded in fusing plant cells not only       make-up of a plant (see article page 13).           surface or by entering their tissue where
with other plant cells but also with animal         Using these new techniques the nutritional          they form nitrogen-fixing nodules. These
and even     human    cells.   In   most   cases,   value of the haricot bean, for example, has         studies have not yet reached the molecular
however, the chromosomes of one of the              been improved by the transfer of a gene             biology or the genetic engineering stage,
fused cells are quickly eliminated and it has       from the Brazil nut.                                but they hold out much promise for tropical
only been possible to obtain complete,                In Europe, Japan and the United States            forestry, sand dune stabilization and the
stable hybrid cells from the fusion of cells        of America, a number of large multina¬              fight against desertification.
from very closely related species. Further¬         tional companies are showing keen interest             Finally, mention should be made of stud¬
more, even when stable stock has been               in these new techniques of plant improve¬           ies being made in the Philippines and Sene¬
obtained, it has proved difficult to regener¬       ment with a view to competing for the world         gal on the use of the water fern Azolla pin-
ate a complete plant from such fused cells.         market. Nevertheless, this branch of bio¬           nata as a biological fertilizer in rice fields
The first success achieved was the regenera¬        technology also offers great opportunities          (seethe Unesco Courier, December 1984).
tion of the pomato, a cross between a potato        for the developing countries. These new             In symbiotic association with the blue-green
and a tomato. However, the plant is sterile         techniques,     which    they   have    already     algaAnabaena this water fern has the ability
and remains no more than a laboratory               acquired or can rapidly master, will enable         to fix atmospheric nitrogen. Ploughed into
curiosity.                                          them to adapt their agricultural production         the soil between harvests, this "green fertil¬
  More recently scientists have succeeded           to meet local conditions and requirements.          izer" can increase the crop by over 50 per




r                                                   The Green Revolution

 RESEARCH into the selection of new                 even better adapted and which gave a better         end of the 1970s. In the Punjab, farm re¬
        high-yield cereal varieties began after     yield. In addition to wheat and rice, this          venues doubled in 1972, six years after the
        the Second World War. Wheat and             research also concerned millet and sorghum,         introduction of new cereal varieties.
rice varieties were selected In Mexico and the      triticale, maize and several leguminous plant         In some regions of Asia where water
Philippines respectively,      then during the      species.                                            resources permitted, the shortening of the
1960s the new strains were used in other              In just over a decade, more than half the         growing period of new rice varieties allowed
parts of the world, and it was later established    surface of corn-growing land and one-third of       two or three crops to be harvested per year.
that they had contributed to a significant          that of rlceland in developing countries had          The prime beneficiaries of the "Green
increase in agricultural yields.                    been sown with high-yield cereal varieties.         Revolution" were the wealthier farmers of

  In the mid-1960s, following the introduction      When the latter are irrigated, and receive ade¬     some developing countries. The countries of
of these high-yield varieties Into several coun¬    quate supplies of fertilizer and weed-killer, the   Africa south of the Sahara were scarcely
tries of Asia and Latin America, the expres¬        yield is two or three times higher than that of     affected; only Kenya and Zimbabwe                      in¬
sion   "Green   Revolution"    was    coined   to   traditional varieties.                              creased the area of land on which new vari¬
describe the various efforts made to increase         The new varieties of wheat were introduced        eties of maize were grown. The wheat and rice
agricultural production in the developing           to India in 1966 and Indian wheat production        varieties were not introduced at the same

countries by means of these new varieties,          had doubled by 1970-1971, when it reached           pace as in Asia where the development of
especially wheat and rice. The cultivation of       23.4 million tonnes. As a result of local efforts   irrigation, adequate fertilizer supplies, and the
these crops required the use of pesticides and      to improve varieties and a more widespread          marketing system of farm produce played an
Irrigation in addition to fertilization and sound   use of selected seeds, output reached 33 mil¬       important role in the success of the "Green
agricultural practices. Cross-breeding be¬          lion tonnes in 1978-1980. From being the            Revolution."

tween these varieties and hardy local breeds        world's second largest cereal importer in           Source: Oue//es biotechnologies pour les pays en développe¬
made it possible to obtain cultivars that were      1966, India had become self-sufficient by the       ment? by A. Sasson, Biofutur/Unesco, Paris. 1986
cent and its effect, which lasts for two years,                  visiae) and certain anaerobic bacteria, such
is equivalent to the use of 60 kilograms of                      as Zymomonas mobilis, convert the sugars
nitrogen fertilizer per hectare.                                 into ethanol with an average yield of 47 per
                                                                 cent, by weight. Several suitable raw mat¬
                                                                                                                        The cloning
                                                                 erials are available in considerable quan¬
        Energy from waste
                                                                 tities at a low price. However, from the
                                                                                                                                  of the oil palm
Biotechnology's contribution in the field of                     economic point of view there is one impor¬
new energy sources is today arousing great                       tant drawback: the ethanol has an inhibiting
interest for two reasons: the foreseeable
                                                                                                                     The oil palm (Elaeis guineensisj is culti¬
                                                                 effect on the micro-organisms that produce          vated as a source of oil in the humid tropic¬
exhaustion of our supplies of fossil energy                      it and the maximum concentration in the             al zones of Africa, the Americas and
(oil and coal), and the world energy crisis                      reactors cannot exceed 8 to 10 per cent. As a       South-east Asia, where oil palm planta¬
which, since 1973, has weighed heavily on                                                                            tions   cover    several    million      hectares.
                                                                 result, the distillation of bio-ethanol and its
the economies of all countries, but par¬                                                                             Selection cycles to produce higher-yield¬
                                                                 complete dehydration, which is essential to
                                                                                                                     ing varieties through sexual reproduction
ticularly on those of the countries of the                       its use as a fuel, are costly operations con¬
                                                                                                                     were very long, and their results were only
Third World.
                                                                 stituting about 60 per cent of the cost             perceptible after 15 or 20 years. In the
    One achievement, which has already                           price.                                              1970s, attempts were thus made to perfect
been developed on a large scale in a number                           In Brazil, ethanol fuel is produced from       in vitro propagation of the oil palm using
of countries, is the production of biogas                        sugar-cane on a large scale. At present pro¬        Photo © IRHO-CIRAD/ORSTOM, Paris
from   cellulose          and    animal       and    human
                                                                 duction is running at 8.4 million tonnes
wastes.    This      is    based      on    the    anaerobic
                                                                 which in energy terms is equivalent to 5.6
digestion         of cellulose        and     nitrogenous        million tonnes of super-grade petrol. In
organic matter by mixed populations of                           agricultural terms the yield is 4.7 tonnes per
microbes consisting of bacteria that break                       hectare of sugar-cane per year.
down cellulose into organic acids and other                           At present, the cost price of bio-ethanol
bacteria that convert these organic acids                        exceeds that of petrol by $380 per tonne. In
into methane.
                                                                 Brazil, however, the economic motivation
    Experience acquired in India indicates                       for producing bio-ethanol is to improve the
that   the    manure           from    ten    cows    would
                                                                 balance of payments by reducing imports of
provide a daily yield of 1.8 cubic metres of                     petrol and to provide an outlet for the sugar
biogas, which is the equivalent of 1.3 litres                    industry which has been badly hit by the fall
of petrol, enough to cook the food for four                      in the price of sugar on the world market.
people or operate a hundred candlepower                               Bio-ethanol is arousing great interest
lamp for fourteen hours. What is more, the                       elsewhere for similar reasons. In the United
residue constitutes an excellent fertilizer of
                                                                 States, "Biohol", an automobile fuel con¬
a quality         far superior to             the    original    taining 10 per cent ethanol produced from
manure.
                                                                 maize, has been on the market for several
    A million of these cheap and simple bio-                     years. In Western Europe it is planned to
gas digesters are in service in India and                        produce 3.4 million tonnes of bio-ethanol
more than seven million are in use in China.
                                                                 annually. The aim of this project is to make
Production of biogas on farms can be                             use of European surpluses of wheat and
expected to spread soon to other agri¬                           sugar-beet. There is also an ecological
cultural     areas        in   which       other    forms   of
                                                                 motivation. Added to automobile petrol in
energy are not available. From the ecologi¬                      a proportion of 5 per cent, ethanol can
cal viewpoint, biogas has the great advan¬                       replace the tetraethyl lead anti-knock addi¬
tage that it can replace firewood, thus                          tive now used in petrol, but shortly to be
contributing          to       the    struggle       against     banned because of its toxic effects.
deforestation and desertification.

    Biogas production is also increasing in
                                                                           Bridging the protein gap
the industrialized countries as well as in

large towns and heavily populated rural                          Generally speaking, proteins, or the lack of
                                                                                                                     tissue culture, and since 1981 oil palm
areas in general. The main economic gain                         them , constitute the major nutritional prob¬       plantlets have been produced on a semi-
here is that the treatment of waste water                        lem facing the developing countries. Statis¬        industrial scale at the La Mé research sta¬
and the handling of agro-industrial wastes                       tics published by the Food and Agriculture          tion in the Ivory Coast (1) using a cloning
and the animal waste from intensive stock-                       Organization       of   the   United    Nations     technique developed by British and
                                                                                                                     French researchers in the 1970s. Photos
rearing can be turned to advantage by the                        (FAO), show that average total protein
                                                                                                                     show some of the stages in the cloning
production of methane. Already several                           consumption per head of population in the
                                                                                                                     process. Fragments of very young leaves
urban water treatment plants in Europe                           developing countries is only half that of the       are carefully removed from the tip of a tree
meet all their energy requirements by the                        rich countries. The difference is even more         (2) and placed in a nutrient medium where
production of biogas.                                            marked with regard to protein of animal             calluses develop (3). After going through a
                                                                 origin, average consumption of which in the         second and then a third culture medium
                                                                                                                     the calluses evolve into "embryoids" (4)
          Green gasoline                                         developing      countries     is   13 grams   per
                                                                                                                     comparable to the embryos obtained by
                                                                 day      a mere 22 per cent of that in rich coun¬
                                                                                                                     sexual reproduction. They multiply spon¬
The production of liquid fuels, in particular                    tries    and this falls to 4 grams per day in       taneously, and this multiplication is fos¬
ethanol, is another major contribution of                        the poorest regions of Africa and Asia.             tered in a fourth culture medium. A fifth
biotechnology in the field of new energy                           In the developing countries a great vari¬         culture makes it possible for the embryos
sources. A large number of agricultural raw                      ety of agricultural products and wastes lend        to develop into young leaved plantlets (5).
                                                                                                                     The   shoots    are   transferred   to    a   sixth
materials can be used for the production of                      themselves to the production of single-cell
                                                                                                                     medium in which roots are induced (6),
ethanol by fermentation, including the                           edible protein. These include, in particular,
                                                                                                                     while in a seventh medium entire young
sucrose      in    sugar-cane,         sugar-beet       and      ligno-cellulosic matter which is available in       plants are obtained for planting in soil (7).
molasses, the starch from cereals, manioc                        large quantities at a low price. According          It takes about 3 months to obtain a 12 cm
and potatoes, and the inulin from Jerusalem                      to    the   United      Nations    Environment      shoot from an embryoid.
artichokes.
                                                                 Programme (UNEP), the world crop of
    Brewer's yeast             (Saccharomyces cere-              cereals produces annually 1,700 million             L
8
Powerful protoplasts




     Techniques for the cloning of plants are
     now so refined that a single cell removed
     from the body of a plant can be cultured in
     the laboratory and then induced to re¬
     generate a complete individual plant.
     Drawings at left and below are a schematic
     representation of the cloning process
     used by Prof. James F. Shepard and his
     colleagues at Kansas State University to
     regenerate a complete potato plant from
     protoplasts (living cells stripped of their
     outer wall) prepared from leaf cells. Small
     terminal leaves are first removed from a

     young potato plant (1).    The leaves are
     placed in a solution containing a combina¬
     tion of enzymes capable of dissolving the
     cell wall to produce protoplasts (2). The
     solution also causes the protoplasts to
     withdraw from the cell wall and to become

     spherical, thereby protecting the proto¬
     plasm during the disintegration of the
     walls (3). The protoplasts are next grown
     in a culture medium (4) where they divide
     and begin to synthesize new cell walls (5).
     After 2   weeks   of culture   in   these   con¬
     ditions, each protoplast gives rise to a
     clump of undifferentiated cells or micro-
     calluses (6). These microcalluses develop
     into full-size calluses in another culture
     medium (7) and their cells begin to dif¬
     ferentiate, forming a primordial shoot (8).
     The shoot develops into a small plant with
     roots in a third culture medium and is then        tonnes of straw, to which can be added
     planted in soil (9). Under appropriate con¬        some 127 million tonnes of bagasse from
     ditions protoplasts from 2 different plants
                                                        sugar-cane and pulp from sugar-beet. At
     can be fused to form a cell possessing
                                                        present, the main obstacle to their use for
     genes of plants which cannot be crossed
     using classic methods. The fused proto¬            the production of proteins is the lack of
     plasts of some species can be grown into           sufficiently active microbial strains for this
     plants in a process known as somatic               specific purpose. Recently achieved labora¬
     hybridization.
                                                        tory results suggest that this problem will
                                                        soon be overcome.

                                                          Cuba is, at present, the only developing
                                                        country producing single-cell edible protein
                                                        from agricultural raw material. Eighty
                                                        thousand tonnes of forage yeasts for use as
                                                        animal feed are produced annually from
                                                        sugar-cane molasses. The Cuban example
                                                        will probably soon be followed in other
                                                        countries, such as India, where molasses is
                                                        also available at a low price.




10
33^
                                                                        yj.




                                                                                                                                                           ©




  For a long time now Western Europe has                    Born in Europe some thirty years ago, this      Protein enrichment by fermentation is a
                                                                                                            branch of biotechnology that could help
been producing single-cell edible protein                   branch of biotechnology has developed to
                                                                                                            some developing countries increase their
from various agro-industrial wastes such as                 the point where there are factories with a
                                                                                                            protein resources. Microbial fermentation
lacto-serum (80,000 tonnes per year) and                    production capacity of 100,000 tonnes per       of such crops as manioc, which contain
the sulphite liquors used in paper-making                   year.                                           much starch and relatively little protein,
(25,000 tonnes per year). As with biogas,                     The oil treatment processes make use of       yields a product with a substantially high¬
the main economic incentive for this pro¬                   yeast micro-organisms (Candida lipolytica       er protein content. The banana is a fruit to
duction is the elimination of the cost of                                                                   which this process could be applied, and
                                                            and Candida tropicalis) which are derived
                                                                                                            several banana-producing countries are
handling potentially polluting wastes. It is                from diesel oil or from paraffin, previously
                                                                                                            investigating the possibility of using in
to be expected that the same will happen                    extracted from crude oil, and having a yield    this way the high proportion of fruit re¬
soon in the developing countries where                      of 100 per cent by weight. In the case of       jected for export and usually wasted.
increasing industrialization is making pro¬                 methanol, chemically derived from natural       Above, harvesting bananas in Martinique.
tection of the environment an ever more                     gas, the biomass produced is that of bacteria
urgent necessity.                                           such as Methylophilus methylotropha whose
  One of microbiology's most promising                      yield on this substrate is of the order of 50
contributions to the problem of edible pro¬                 per cent, by weight. The methanol treat¬
teins is their production on an industrial                  ment processes make use of specific meth¬
scale from oil, methanol and natural gas.                   ane-eating bacteria (Pseudomonas meth-



                                                                    8




After J.F. Shepard in Scientific American, New York, 1982

                                                                                                                                                      11
ylotropha or Methyiococcus capsulatus) in             tein-rich microbial biomass and residual              is too low for it to be used as animal feed, is
conjunction with other species whose task is          agricultural raw material whose nutritional           a complete write-off. For a number of Cen¬
to prevent the inhibition of the bacteria by          value is thus enriched. This relatively sim¬          tral American countries which export sev¬
intermediate accumulation of methanol.
                                                      ple technology has the advantage that it can           eral million tonnes of bananas annually, the
     Very large-scale experiments with the            be used both on a large industrial scale and           prospect of recuperating wastage on this
products thus obtained from oil and meth¬             in    small,   inexpensive production units            scale by use of the fermentation process is
anol have demonstrated conclusively their             located in rural communities. This means               clearly of the greatest interest and this
high        nutritional    value   and   complete     that high-quality edible protein can be pro¬           possibility is being actively investigated in
innocuousness. Up till now, these edible              duced from a wide range of agricultural raw            Mexico, Guatemala and the West Indies.
proteins have been marketed exclusively as            materials that are too costly or available               Finally, the third major contribution that
animal feed, but preliminary studies have             locally only in quantities too small for use          biotechnology has to offer to the solution of
shown that there is nothing to prevent their          with standard single-cell edible protein pro¬         the world problem of edible protein is the
being used directly as food for humans.               duction methods.                                      industrial production of amino acids as a
     Following the first oil crisis of 1973, pro¬          In all the tropical regions, manioc (also        complement to plant proteins. Many such
duction of single-cell edible protein from oil        known as cassava) is the chief agricultural           proteins, in fact, are only of limited nutri¬
and from methanol slowed down in West¬                raw material potentially available for pro¬           tional value because of their lack of certain

ern Europe due to the increased cost of the           tein enrichment. Cultivated throughout                essential amino acids which man and other
raw material. In Eastern Europe and in the            Africa, in Asia and Latin America, the                mono-gastric        animals   (including      pigs,
USSR, however, it has developed consider¬             world production of manioc is of the order            young ruminants and poultry) are unable to
ably and now amounts to some 3 million                of 100 million tonnes. Very rich in starch,           synthesize and therefore must find in their
tonnes per year.                                      but containing practically no protein, man¬           food. This is the case in particular of lysine,
     This    branch   of    biotechnology   is   of   ioc is used above all as a supplementary              which is the amino acid in which cereals are

obvious interest to those developing coun¬            energy food. Furthermore, although under              most notably deficient and lack of which is
tries that are producers of oil and natural           good conditions it can yield 50 tonnes per            the main cause of malnutrition in the Third

gas, since these raw materials are available          hectare and over, it is normally only culti¬          World. Almost all the amino acids used as a
to them in large quantities at prices well            vated on small patches of land using rudi¬            complement to plant proteins are obtained
below the world market price. The Organi¬             mentary methods with low productivity.                by fermentation using hyper-productive
zation of Arab Petroleum Exporting Coun¬               At present, the only country in which                bacterial strains selected genetically.
tries, for example, proposes as a first step to       manioc cultivation has been developed                    Apart     from     methionine,       which    is
produce 100,000 tonnes of single-cell edible          rationally is Thailand, which exports 7.5             basically intended for use in animal feed,
protein a year, either from oil or from meth¬         million tonnes of manioc root to the Euro¬            lysine is the only amino acid produced in
anol, and it estimates the potential market           pean Community each year.                             large quantities (40,000 tonnes per year). It
in the Middle East and in the Maghreb at                   Starting with dried manioc with an initial       has been estimated that the world deficit in
more than a million tonnes. It should be              content of 90 per cent starch and less than 1         lysine, most marked in Africa and the Far
pointed out that this amount of protein               per cent protein, fermentation with an                East, is 136,000 tonnes for human food and
could be obtained from 0.1 per cent of their          amylolytic mould (Aspergillus hennebergii)            three      times    that   figure     for   animal
total oil production.                                 yields a product containing 20 per cent well-         foodstuffs. As things stand at present, the
     Protein enrichment of foodstuffs by fer¬         balanced proteins and 20 to 25 per cent               cost price of lysine is still too high to ensure
mentation is another promising prospect.              residual sugars. In this way manioc can               satisfaction of Third World needs and to

Application of modern biotechnological                provide nearly 2 tonnes of protein per hec¬           compete with soya in animal feed. The sit¬
methods to this practice, which is tradi¬             tare, that is, three times more than can be           uation is the same for other amino acids, in
tional in Africa and the Far East, seems set          obtained from the cultivation of soya or              particular threonine and tryptophan,
fair to provide the developing countries              other leguminous plants.                              which, after lysine, are the chief elements
with a substantial increase in their protein               The banana too is a raw material with a          lacking in plant proteins. However, it is
resources for human and animal consump¬               bright future. In the collection centres of           reasonable     to   assume    that,    thanks   to
tion.                                                 exporting countries, 20 to 30 per cent of the         genetic engineering, substantial progress
  The end product of this fermentation pro¬           fruit gathered is rejected. This rejected             will soon be made.

cess is a directly consumable mixture of pro          fruit, whose protein content at 1.1 per cent

                                                                                                            JACQUES C. SENEZ, French biologist and uni¬
                                                                                                            versity teacher, is a former Secretary-General of
                                                                                                            the Unesco-sponsored International 'Cell Re¬
                                                                                                            search Organization (ICRO) and a consultant
                                                                                                            member of the Protein Advisory Group of the
                                                                                                            United Nations. A past Secretary-General of the
                                                                                                            International Union of Microbiological Societies
                                                                                                            (IUMS), he is the author of a number of studies
                                                                                                            on microbiology and bacterial biochemistry. In
                                                                                                            the late 1960s he initiated the production of
                                                                                                            Single Cell Protein (SCP) from petroleum.




                                                                                                        2   Many developing countries are engaged in
                                                                                                      I     programmes to harness the techniques of
                                                                                                      e     biotechnology for national development.
                                                                                                      §     Left, fermenters of a Cuban factory pro-
                                                                                                      $     ducing single-cell edible protein from
                                                                                                    ©       molasses. The installation produces some
                                                                                                    %       40 tonnes of protein a day for use as anim-
                                                                                                      £     a/ feed.



12
by Bernard Dixon




                                                                                         The gene
                                                                            revolution




                                              GIVEN the mixture of benefits and                  which they are part. The astronomically
                                                        problems spawned by the first            long DNA molecule can be subdivided into
                                                        Green Revolution two decades             regions genes which determine particu¬
                                                                                                 lar characteristics. Recombinant DNA is
                                              ago (see box page 7) , it is not surprising that
                                              both optimism and apprehension surround            the name given to the product when a piece
                                              the application of genetic engineering now         of DNA from one organism is combined
                                              to agriculture tomorrow. Mixed reactions           artificially with that from another.
                                              are appropriate, because those develop¬              Genetic manipulation of this sort is the
                                              ments focused upon so-called recombi¬              basis for the boom that has occurred during
                                              nant DNA       are destined to have even           the past decade in biotechnology. Such
                                              more far-reaching effects than the tech¬           activities were, of course, possible pre¬
                                              niques deployed in the first revolution.           viously. Some, like the art of fermenting
Photo above shows the distinctive knot¬                                                          sugar to make alcoholic drinks, are almost
                                              Today's new wizardry could undoubtedly
like growths or nodules which form on the                                                        as ancient as Man himself. Others, includ¬
                                              transform agriculture throughout the
roots ol legumes (plants of the pea family)
                                              world. At the same time, its precision in          ing the first mass production of antibiotics,
when they are infected by certain bacteria.
These bacteria, known as rhizobia, take       modifying living cells offers a stern chal¬        were developed earlier this century. But all
nitrogen from the air and change it into      lenge to our prudence and wisdom.                  of these processes were based on organisms
forms the plants can use. One important         At the centre of the stage is deoxy¬             as they occur in nature albeit with other,
aim of research in biotechnology is to ex¬                                                       equally natural, methods being used to
                                              ribonucleic acid (DNA), the material which
tend this process of nitrogen fixation to
                                              carries in coded form the hereditary instruc¬      select high-yielding strains.
other crops by incorporating nitrogen-fix¬
                                              tions responsible for the behaviour of cells         The arrival of recombinant DNA, how¬
ing genes into their genetic heritage. The
goal is proving difficult to attain.          and the plants, animals or microbes of             ever, has altered the rules profoundly. It


                                                                                                                                           13
has already greatly enhanced our specificity     pieces of DNA in this way, genetic engi¬         teria and gives the plants the capacity to
and power in tailoring living organisms for      neers are beginning to create pedigree           produce a toxin that is lethal to insects. The
beneficial purposes. In future, it will extend   microbes for a wide range of new purposes        inbuilt insecticide makes the plants resistant
our range of options much further.               in agriculture, medicine and industry.           to insect attack and does not, of course,
  The breakthroughs which have led to this          Although genetic manipulation is taking       have to be applied repeatedly. Some plants
historic watershed in the fabrication of         longer to perfect in plants, several tech¬       can mobilize defences against virus infec¬
novel plants and microbes happened during        niques are now emerging. The most useful         tion through a process analogous to immu¬
the early 1970s. The key discoveries were        so far is based on Agrobacterium tumefa-         nization in animals,      and this suggests
made by molecular biologists who learned         ciens, a bacterium that causes crown galls       another route for genetic alteration. Incor¬
how to splice into bacteria genes which they     on many flowering plants. It contains a          poration of one virus gene into tobacco has
had taken from other bacteria, and even          tumour-inducing (Ti) plasmid which is            helped to protect this plant against subse¬
from totally unrelated animal or plant cells.    responsible for triggering the disorderly        quent inoculation with the entire virus.
They first found out how to locate the par¬      growth that appears as ugly galls. Genetic          Another          development     concerns
ticular gene they wanted among the count¬        engineers have learned how to delete the Ti      weeds      a major limitation on crop hus¬
less numbers on the DNA of one organism.         plasmid's tumour-inducing genes and use it       bandry in most countries. Although weeds
Then they used natural catalysts called          as a vector with which to carry new genes        can be combatted using selective her¬
enzymes to cut out that gene and "stitch" it     into plants.                                     bicides, these often impair the growth of the
into a vector. This is usually a virus or a        A serious drawback so far is that while A.     crop too. It is now possible, however, to
plasmid (a piece of DNA that replicates          tumefaciens infects potatoes, tomatoes, and      introduce resistance genes into tobacco and
independently from the nucleus, the main         many forest trees, it does not normally          petunia. One such manipulation results in
repository of DNA). The vector became a          attack the monocotyledons such as cereals,       the synthesis of enzymes in the plant that
vehicle for ferrying the selected DNA frag¬      which are prime targets for genetic im¬           are no longer sensitive to the inhibitory
ment into the recipient. Once inside its new     provement.     Progress   is   being   made,      action of the herbicide glyphosate. Com¬
host, the foreign gene divided as the cell       however, and recent research indicates that      mercial companies now plan to market a
divided   leading to a clone of cells, each      rice in particular can be manipulated using      package containing both herbicide and
containing exact copies of that gene.            the Ti plasmid. Alternative vectors and           resistance seed.

  Because the enzymes used for genetic           other methods of transferring genes are also        Some 70 per cent of the world's intake of
engineering are highly specific, genes can       being developed. One exciting possibility is     dietary protein consists of cereal grains and
be excised from one organism and placed in       to use an electric current to promote the        seeds of legumes. On their own, neither
another with extraordinary precision. Such       incorporation of foreign DNA. This works         cereals nor legumes can provide a balanced
manipulations contrast sharply with the          with maize cells, though scientists still have   diet for human consumption, because the
much less predictable gene transfers that        to persuade the cells to develop into whole      "storage proteins" they each contain are
occur in nature. They also make it possible      plants.                                          deficient in one or more amino acids. Now,
to splice genes that would be unlikely to          One gene that has been transferred into        added to analyses of the proteins in both
come together naturally. By mobilizing           tobacco by A. tumefaciens comes from bac         cereals and legumes, we have precise infor-




          How to recombine DNA                              Drawing shows how a micro-organism (in this case a bacterium) is manipulated
                                                            to make it synthesize a desired substance. (1) A bacterium contains a plasmid,
                                                            which is a circular piece of DNA. This plasmid is isolated (2) and, with the help of
                                                            a restriction enzyme, opened in a precise spot (3). Meanwhile, with the help of
                                                            other restriction enzymes, the gene for synthesis of the desired substance is
                                                            isolated from the DNA of another organism (4). Still using enzymes, this gene is
                                                            grafted onto the previously opened plasmid (5). The plasmid is re-introduced
                                                            into a bacterium (6). The manipulated bacteria are put into a culture, where they
                                                            synthesize the desired substance. (7)




                                                                                                                                                   o
                                                                                                                                                   ó




14
mation about the DNA sequences coding
for them. This knowledge may well lead to
methods of altering those sequences or
introducing new genes that code for a more
balanced spectrum of amino acids.
  The world's energy and food supplies rest
upon the ability of green plants to convert
atmospheric carbon dioxide into carbo¬
hydrates, fats and proteins, using light from
the sun. Unfortunately, the mechanism by
which they consume carbon dioxide is inef¬
ficient in those plants, such as wheat, barley
and potatoes, that are cultivated in tem¬
perate climes. Oxygen in the atmosphere
interferes with the first enzyme involved in
the assimilation of carbon dioxide. Consid¬

erable efforts are now being made to alter
the DNA sequence of the gene coding for
this enzyme, to prevent the deleterious
action of oxygen. Other researchers are try¬
ing     to    introduce into         temperate      zone
plants certain genes taken from maize,
which has a more efficient mechanism of

carbon dioxide uptake.                In nature this
mechanism appears to operate only at
higher temperatures, but there are hopes of
"switching it on" in cooler areas.
  Another atmospheric gas is the subject of
parallel efforts to make plants more effi¬
cient. Nitrogen constitutes 80 per cent of
the air, yet plants cannot use the gas
directly. Hence the heavy dependence of
modern intensive agriculture on fertil¬
izers        nitrate,    ammonia      or    urea       syn¬
thesized by the chemical industry. Natural
nitrogen        fixation     depends       in   part    on
rhizobia, bacteria that live symbiotically
with legumes such as peas, beans and
clover.        The      bacteria   grow     on     sugars
provided by the plant, and are maintained
in characteristic nodules on the plant. There
they         convert      nitrogen     directly        into
ammonia, leading in turn to the synthesis of
plant proteins.
  Molecular biologists have now isolated
and characterized several of the genes
required for nitrogen fixation. They have
found, however, that many more bacterial
and plant genes are involved than they first                  fixation. Drought resistance which depends        A key area in biotechnology research is
imagined. This makes the manipulation of                      on a reduced area of leaf surface, for exam¬      concerned with the development of tech¬
those genes correspondingly more difficult.                   ple, may be caused by the interaction of          niques for isolating genes of one plant and
So it will be some years before we can enjoy                  multiple genes.                                   introducing them into another as a means
                                                                                                                of endowing the host plant with new char¬
the cost and energy savings that should                         Microbes that contribute to healthy plant
                                                                                                                acteristics such as higher protein content
accrue by providing crops such as wheat and                   growth are also on the drawing board for
                                                                                                                or resistance to pests. One promising
maize with the ability to fix their own                       genetic engineering. One possibility being        technique for transferring genes uses
nitrogen.                                                     examined is the production and deliberate         Plasmids (small pieces of genetic material)
  Drought and high temperatures are                           release of rhizobia that fix nitrogen more        from a bacterium    which causes     tumour

unwelcome to all plants, despite being bet¬                   efficiently than natural strains. Other bacte¬    growths when it infects certain plants,
                                                                                                                above. It is possible to delete the plasmid's
ter tolerated by varieties that have evolved                  ria capable of forming nitrogen-fixing part¬
                                                                                                                tumour-inducing genes and use the plas¬
in such environments. Desiccated soils also                   nerships with wheat and maize are also            mid to ferry new "useful" genes into
often contain high levels of salts and metal¬                 being considered. A third type of prospect        plants. Genes of a bean protein have been
lic elements, which are toxic to plant                        follows the discovery by researchers at the       transferred to the sunflower using this
                                                                                                                method.
growth. Genetic engineers would dearly                        University of California, Berkeley, that
like to fabricate plants resistant to such                    frost damage to strawberries is triggered by
stresses, but success is unlikely in the near                 bacteria which act as nucleii for the forma¬

future. Before being able to identify the                     tion of ice crystals on leaves. The cause is a
relevant        DNA       sequences     for      transfer     particular bacterial protein, the gene for
between plants, they require a far better                     which the California biologists have learned
understanding of the many ways in which                       to delete. They believe they can prevent the
plants respond to their environment. An                       extremely costly frost damage by spraying
additional problem may be the involvement                     crops with this "ice minus" strain , which will
of several different genes, as with nitrogen                  outgrow the natural flora.



                                                                                                                                                         15
The use of genetic engineering in food
                                                                                                       production offers many potential advan¬
                                                                                                       tages. At the same time, questions have
                                                                                                       been raised about the possible risks in¬
                                                                                                       volved in releasing genetically modified
                                                                                                       living organisms into the environment.
                                                                                                       One case which led to widespread debate
                                                                                                       and concern in the United States arose

                                                                                                       from the development and use of geneti¬
                                                                                                       cally modified microbes known as ice-
                                                                                                       minus bacteria to protect strawberries
                                                                                                       from frost damage. In photo, the leaf at left
                                                                                                       has been treated with ice-minus bacteria.

                                                                                                       The leaf at right froze when dipped into
                                                                                                       supercooled water.




                                                                                I


©




       Genetic engineering holds considerable        in America, even natural weeds can cause          about an organism's potential safety or per¬
    promise too in the improvement of "biolog¬       considerable havoc.                               formance in nature. The scientific con¬
    ical insecticides", microbes that attack pests     The prospect of genetically engineered          sensus is now for a gradual approach, a
    and have enormous ecological advantages          crops      themselves   becoming    weeds    is   priori evidence about a released organism's
    over their chemical counterparts. Bacillus       remote, however, because crop varieties           likely behaviour being used as the basis for
    thuringiensis, for example, has been used        cannot compete well with other plants when        successively larger trials during which expe¬
    for many years to combat nuisance species,       left unattended. The inherent difficulties of     rience and confidence are gathered about
    but it and similar bacteria and viruses may      mobilizing plant genes also make it unlikely      how it actually does behave.
    well be made more powerful by recombi¬           that unwelcome varieties will be produced           There is one other argument against the
    nant DNA. One possibility is illustrated by      accidentally. And there is always the pos¬        much-publicized view in the USA that
    the pine moth, which damages lodgepole           sibility of destroying by fire or other means     organisms     carrying    recombinant      DNA
    pine trees in northern Britain. In other parts   an engineered plant, released initially in a      should never be released for purposes such
    of the country, the moth is controlled natu¬     defined area, that did create problems.           as pest control. One third of the world's
    rally by a baculovirus that infects the cater¬   Nonetheless, field trials with novel plants,      crops are now lost through infection and
    pillars. There are now plans to make the         particularly crops able to cross-fertilize with   pestilence. It would be foolhardy not to
    virus more efficient at killing caterpillars     weeds, need to be very carefully monitored.       make use of an ecologically acceptable tech¬
    and to release it in the pine plantations. The     Greater caution still is required with engi¬    nique capable of achieving even a modest
    first experiments are being carried out with     neered microbes, which would be broadcast         reduction in that toll.
    a virus that has been altered only by having     in astronomical numbers and be impossible
    a "marker" introduced into a non-coding          to trace in their entirety should anything go
    region   of   its   DNA.   This   will   allow   awry. But it is reassuring that no health,
    researchers to follow the virus's distribution   environmental or other dangers have been
    and survival after spraying. If all goes well,                                                     BERNARD DIXON, British science writer and
                                                     caused by recombinant organisms since
                                                                                                       consultant, is European editor of The Scientist
    the virus may be given a genè allowing it to     they were first fabricated over a decade ago.
                                                                                                       magazine and was formerly (1969-1979) editor
    synthesize an insect-killing toxin. The          Moreover, biologists now agree that there is      of the British scientific ¡ournalTUe New Scientist.
    potential for this technique in other coun¬      no significant difference between a microbe       Notable among his published works are Magnifi¬
    tries, against other destructive insects, is     that has received a new piece of DNA              cent Microbes (1976), Invisible Allies (1976) and
    clear.                                                                                             (with G. Holister) Ideas of Science, Man and
                                                     through artificial manipulation and one that
                                                                                                       Medicine (1986).
      The safety of laboratory and industrial        has acquired the same DNA fragment
    activities using engineered organisms is         through natural mechanisms of gene trans¬
    based on the idea of containment. Facilities     fer. Most experts argue that recombinant
    are graded according to the degree of risk.      DNA manoeuvres are intrinsically safer,
    New questions arise, however, when mi¬           because they can be vastly more precise and
    crobes and plants are to be introduced into      selective. Certain laboratory manipulations
    the environment. There is concern, for           are ruled out anyway by a priori predictions
    example, that weeds may be created acci¬         that they would generate hazardous recom¬
    dentally and be inordinately difficult to        binants.

    eradicate. If such a plant were drought-           Many researchers believe that tests with
    resistant, herbicide-resistant, and frost-tol¬   recombinants should always be restricted to
erant, it might spread quickly over large            closed environments such as greenhouses.
areas of agricultural land and be very diffi¬        But these "microcosms" can never simulate
cult to eradicate. As illustrated by the             the richness of the natural biosphere. So
Kudzu plant in Asia and the water hyacinth           they can never provide conclusive evidence



    16
Tomatomation


     Japan's high-tech food factories
                                                                                                by Koichibara Hiroshi



THE harnessing of high technology to            Light, temperature and humidity are com¬        '85 (see the Unesco Courier, March 1985).
        vegetable farming may be about to       puter controlled in this vegetable factory      This was a major success for a hydroponic
                                                in a Tokyo suburb. High electricity con¬        culture system developed after many years
        trigger a new agricultural revolu¬
                                                sumption is a drawback.
tion in Japan, where some large manufac¬                                                        of research by a Japanese agronomist,
turers are already offering fully automatic                                                     Nozawa Shigeo. The growth of the plant
"factories" in which vegetables are grown in                                                    was accelerated in a nutritive solution which

a computer-controlled artificial environ¬                                                       replaced soil and in an artificially controlled
ment. In their use of automation and high       development is hydroponics, the cultivation     environment. As a result the plant pro¬
technology these facilities resemble auto¬      of plants in nutritive solutions. Factory       duced more than 13,000 tomatoes during
mobile or electronics plants, but instead of    farms are air-conditioned, and high-pres¬       the six months of the Expo.
automobiles or video tape recorders their       sure sodium lamps provide twenty-four-            Daiei,    Japan's    biggest   supermarket
mass production lines produce fresh vegeta¬     hour-a-day illumination. The density of car¬    chain , has installed a factory farm next to its
bles, regardless of season or climate.          bon dioxide, oxygen, temperature and            store in the Tokyo suburb of Fanabashi.
  Strictly speaking, today's factory farming    humidity are controlled by a computer to        This experimental facility, constructed in
technology is based not on biotechnology        maintain an optimum growing environ¬            co-operation with Hitachi Ltd. to grow let¬
but on applying industrial production man¬      ment.                                           tuce for sale in the adjoining supermarket,
agement techniques to conventional agri¬          The hardware used in this process is not      may be the world's first commercial factory
cultural engineering. The aim is to use         new. It is readily available from manufac¬      farm using full automatic hydroponic cul¬
artificially controlled environments to grow    turers of electrical consumer goods, and this   ture technology. The system produces some
plants rapidly and efficiently rather than      may be the reason why Japanese electrical       130 heads of lettuce and other green vegeta¬
improve the adaptation of plants to natural     conglomerates are active in this field. Com¬    bles per day (some 47,000 per year) on a
conditions. Such ideas have already been        panies in Denmark, the United States and        floor space of no more than 66 square
applied to poultry farming, egg production      Austria are also experimenting with vegeta¬     metres. Grown from seed, the lettuce is big

systems, and even the production of foie        ble factories but for the moment the Jap¬       enough for harvesting in only five weeks,
gras. Factory farms may thus make a big         anese seem to be leading the field.             3.5 times faster than plants cultivated using
                                                  In 1985, a "supertomato" plant was dis¬       conventional methods.
impact on conventional agriculture since
they provide planned cultivation regardless     played   in   the   Japanese   government-        In this futuristic factory, the sun is
of weather, season, climate or soil.            sponsored pavilion at an international          replaced by artificial twenty-four-hour
  The   essential   element   in   this   new   exhibition held in Japan,   Tsukuba Expo.       lighting, soil with nutritive solution and


                                                                                                                                             17
farmers with a micro-computer. The crop is       metres and a construction cost of $60,000.
                                                tasty and free from pesticides and her¬          Since May, each factory has been producing
                                                bicides, and is in great demand, regardless      120 heads of lettuce a day. Experiments are
                                                of the price tag, which is double that of        being carried out on the cultivation of other
                                                conventionally grown lettuce.                    vegetables such as tomatoes, cabbage,
                                                  In Mitsubishi Electric's Amagasaki labo¬       asparagus, melon and green peppers. In the
Trays of growing lettuce were rotated up        ratory, a prototype food factory assembly        case of JNR, electric power supplied by its
and down on chain conveyors in this             line succeeded in growing lettuce seedlings      own power plants can be efficiently used at
vegetable factory installation shown in the     from 2 grams to 130 grams in 15 days 6           night when demand is low, and open spaces
Japanese Government pavilion at Expo
                                                times faster than the natural growth rate.       beneath the overhead railway or aban¬
'85, an international exhibition held at Tsu-
kuba (Japan) in 1985. The lettuce were          With specially developed fluorescent             doned tunnels can be utilized as sites.

grown in liquid nutrients, using the tech¬      lamps, the photosynthetic ratio is said to be      Artificial lighting and computers are not
nique known as hydroponics. The 24-             better than that of the sun. Sprouts cloned      essential   elements   in   factory farming.
hour-a-day lighting, carbon-dioxide-rich        from the tissues of mature plants start at one   Hydroponic food factories can be installed
atmosphere    and   constant   temperature
                                                end of a conveyor and move along at the          in developing countries where food facto¬
helped the lettuce to reach maturity in 20
                                                rate of 20 centimetres a day.                    ries may be most needed. Matsushita Elec¬
days, 4 to 5 times faster than normal. The
moving conveyor belts ensured that every          In March 1986 Japanese National Rail¬          tric has, for example, installed a vegetable
plant was exposed to the same amount of         ways (JNR) built two experimental vegeta¬        factory with minimal automation in the
heat and light.                                 ble factories, each with a size of 50 square     Maldives. The system, which has a plastic




18
Green revolution
Green revolution
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Green revolution
Green revolution
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Green revolution
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Green revolution

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Green revolution

  • 1. e Courier w m 1 m ^H . v H v^ "* ^i culture
  • 2. A time to live... Jumping for joy Sierra Leone is a country on the west coast of Africa with a population of some 3,600,000. It takes its name ("Lion mountain") from that given by the Portuguese explorer Pedro da Sintra around 1460 to the peninsula which is the site of Freetown, the country's capital. In 1787 a settlement for freed slaves was established on land where Freetown now stands. In 1961 Sierra Leone achieved independence, and ten years later became a republic. Some 65 per cent of the work force is occupied in agriculture, with rice as the main food crop. Sierra Leone is the world's sixth largest producer of diamonds. Above, body bent back and almost obscuring the ball, a boy throws himself into a game of soccer in a Freetown street. 52 Sierra Leone
  • 3. Editorial March 1987 40th year In the 1960s and 1970s, the development of high-yield cereal varieties 4 combined with the use of pesticides , irrigation and fertilizer brought a The new biotechnologies Green Revolution to some but not all parts of the Third World. This Promise and performance by Jacques C. Senez issue of the Unesco Courier, which is largely devoted to the application of new scientific techniques to agriculture, enquires into the extent to which the Green Revolution is likely to be followed by a "Biotechnological The Green Revolution Revolution" which may help developing countries to solve some of their 13 food production problems. Although the term biotechnology to denote the use of the biochemical The gene revolution by Bernard Dixon and genetic capacities of living organisms for practical purposes is fairly 17 new, man has been engaged in "biotechnological" activities since very early times. Fermentation and the improvement of useful plant and Tomatomation animal varieties by cross-breeding are but two examples. The new Japan's high-tech food factories by Koichibara Hiroshi biotechnology, however, differs from these time-honoured practices in 20 that it uses genetic engineering and techniques of fusing cells of different organisms to surmount previously impassable barriers between species. Hybrids for the year 2000 Genetic engineering (or gene-splicing) , which involves the direct transfer by Raissa G. Butenko and Zlata B. Shamina of genes "those tiny command posts of heredity that tell living cells 22 whether they will become bacteria, toads or men" into the cells of Grains of hope different species has been described as the "most powerful and awesome by Edward C. Wolf skill acquired by man since the splitting of the atom . " 24 In the first part of this issue we look closely at some of these new The rediscovery of traditional biotechnologies: how they work; how they are currently being used in agriculture different parts of the world and to what effect; the latest trends in this 26 field where changes occur quickly and possibilities are vast. While our contributors focus mainly on the direct applications of biotechnologies to Rusitec the cow Food for rumination agriculture in the developing world, they also note present and potential uses in energy production, human and animal medicine and the 27 management of certain environmental problems. Rhizobium, the farmer's Mr. Fixit The second part of the issue asks broader questions. How can the new A Unesco programme to promote biotechnology for development biotechnologies be best harnessed to development in different social , by Edgar J. DaSilva, J. Freiré, A. Hillali economic and cultural contexts? Will they be a panacea or, contrariwise, and S.O. Keya are they likely to aggravate existing disparities between developing 29 countries and those of the technologically advanced world? The new A challenge for the developing world biotechnologies and especially those applied to plants, put great by Albert Sasson possibilities into the hands of those who control them. How should this 34 power best be exercised? How should access to the fruits of research based on plant genetic resources originating in the developing world be Glossary equitably organized? 2 Unesco, which is engaged in worldwide efforts to strengthen rural A time to live... development through training in the biological and agrobiological SIERRA LEONE: Jumping for joy sciences, in applied microbiology and in biotechnology (see article page 27) , is closely interested in the above issues as part of its basic commitment to promote the use of science and technology for the benefit of all humanity. The complex nature of the problems and some possible approaches and solutions are traced by Dr. Albert Sasson in the article which forms the conclusion of this issue. Editor-in-chief: Edouard Glissant Cover: Photo © Periscoop, Paris Italian Turkish Macedonian A selection in Braille is The Courier English French Hindi Urdu Serbo-Croat Finnish Swedish published quarterly in English, A window open on the world French, Spanish and Korean Spanish Tamil Catalan Slovene Basque Published monthly in 32 languages Russian Hebrew Malaysian Chinese Thai by Unesco German Persian Korean Bulgarian The United Nations Educational, Arabic Dutch Swahili Greek Scientific and Cultural Organization ISSN 004 1-5278 7, Place dc Fontenoy, 75700 Paris. Japanese Portuguese Croato-Serb Sinhala N"3-1987-CPD-87-l-443 A
  • 4. by Jacques C. Senez The new biotechnologies Promise and performance SINCE the beginnings of civilization, hopes, some of which, such as the produc¬ sugar is another example of a social and man has been a biotechnologist, tak¬ tion of human insulin by bacteria recom- economic backlash due to biotechnology. ing advantage of the activities of bined in vitro, have already become reality. Due largely to the production of iso-glucose micro-organisms of whose very existence he Today, these methods are on the verge of in the United States, this sugar price col¬ was unaware, to produce foodstuffs and fer¬ finding new applications of considerable lapse has spelled ruin to a number of tropi¬ mented drinks. Over the centuries, the economic and social importance in the field cal countries whose economies are based on practices by which he did this gradually of agriculture. It would be wrong, however, sugar-cane. developed, in a makeshift, empirical fash¬ to think that the prospects for biotechnol¬ Fortunately, not all biotechnology ion, to attain a high degree of perfection. ogy are limited to the field of genetic engi¬ applications entail problems such as these. Yet biotechnology proper, in the sense of neering. Recent advances in fundamental However, there is a danger that some of the scientific use of biological principles for knowledge and techniques in the physiol¬ them will further increase rather than practical purposes, only emerged at the end ogy of cells, biochemistry, enzyme catalysis diminish Third World dependence on the of the last century with the birth of micro¬ and bioengineering are just as promising. richest and most scientifically advanced biology and its early application to indus¬ It is generally thought that there is a great countries (see article page 29). trial fermentation processes. future for biotechnology in the developing Bearing this in mind, the developing Since the Second World War, biology has countries, particularly in its applications to countries must concentrate their efforts on made prodigious progress. In just a few agriculture. These hopes are well founded, programmes which are both of direct inter¬ years the basic mechanisms of life and but it should not be forgotten that progress est to them and which can be implemented heredity at the molecular level have been involves potential dangers against which all immediately within the limitations of their unveiled, thus opening up limitless hori¬ possible preventive measures should be financial and economic resources. Many zons. Some of these prospects, in particular taken. such opportunities are open to them in agri¬ that of the development of genetic engi¬ The first major achievement of agri¬ culture in which two avenues in particular neering (see article page 13) with its con¬ cultural biotechnology was the "Green beckon: that of primary production, where notations of man the creator, captured the Revolution", whose ambitious objectives there are possibilities in the field of plant imagination and fired the enthusiasm of the have been largely achieved (see box page improvement and nitrogen fixation, and general public. 7). Thanks to the Green Revolution India, that of bioconversion of agricultural prod¬ The transfer of genetic material between Bangladesh and several other Third World ucts and wastes into energy and food organisms as widely different as bacteria, countries have achieved self-sufficiency in resources. plants, animals and man gave rise to great food. This was a true success, but it brought in its train a number of unforeseen social New techniques consequences. The farming of high-yield for better plants cereals requires considerable investment in fertilizers, pesticides and irrigation which Plant improvement by the traditional many small farmers were unable to make. methods of selection and cross-breeding is As a result many of them had their fields as old as agriculture itself. Thanks to recent taken over by the large landowners and advances in knowledge of the genetics and were forced to move to the cities and swell physiology of plants these methods have the ranks of the sub-proletariat. been refined and will long continue to pro¬ The recent collapse in the world price of duce very important results. During the past thirty years, for example, the yield of maize has increased from 12 to 62 quintals per hectare, while that of wheat has grown Egyptian bakers and brewers of 3,500 on average by one quintal per hectare per years ago are shown at work in this scene year. Similar progress has been made with from a Theban tomb. "Biotechnological" processes such as microbial fermenta¬ rice, the second most important of the great tions have been used for thousands of cereals in worldwide use. Today, the Inter¬ years to produce beverages and foods national Rice Research Institute (IRRI), such as beer and cheese. < set up in the Philippines in 1962, has a col¬ © Drawing taken from A History of Technology lection of 60,000 varieties of rice (see the © Oxford University Press Unesco Courier, December 1984).
  • 5.
  • 6. Drawing shows in highly simplified form one of the techniques used in modem biotechnology for experimentation under controlled conditions with plant cells, tis¬ sues and organs and for vegetative (i.e. non-sexual) propagation of plants in ster¬ ile laboratory conditions. The sterilized plant material which is cultured in the nut¬ rient medium may be a meristem (see drawing at bottom of page), or some other piece of plant tissue (see photo story pages 8-9), or a protoplast, a plant cell whose outer walls have been removed plant culture of colony of regeneration mini- greenhouse (see page 10). From this organ, tissue, or meristem or cells of plantlets cells protoplast, a proliferating clump of dis¬ multiplication organized tissue called a callus can be in sterile obtained. From this it is possible to re¬ conditions generate whole intact plants, and to pro¬ duce many genetically identical copies, known as clones, in a relatively short time. A one-cubic-centimetre culture may con¬ In addition to improving yield, the main culture of the meristem or other plant tain one million cells each carrying the purpose of selection is to obtain new vari¬ tissues. Meristem is the name given to a potential of becoming an entire new plant. eties which are resistant to parasites and to grouping of embryonic cells situated at the By selecting cells with certain properties, the process of breeding new varieties of bacterial and viral diseases. In recent years tip of the plant stem (see drawing below). disease-resistant, stress-tolerant crops, a number of new techniques have made Cultivated in aseptic conditions on a solid, trees or flowers can be greatly their appearance, some of which are nutritive culture medium, these cells accelerated. already in use while others are still at the proliferate producing a callus which can be laboratory stage. One of their main aims is divided and reproduced many times. to reduce considerably the time needed for Treated with plant hormones (auxins, a new variety to be put on the market and cytokins and gibberelins), the calluses diffe¬ months, 2,000 million identical tubers, brought into large-scale cultivation. Using rentiate into plantlets having all the prop¬ spread over an area of 40 hectares, were classic methods the lead time required to erties of the original plant. obtained from a single potato tuber derived achieve this is of the order of ten years, By this means, in a period of eight from a meristem, that is a rate of propaga¬ whereas, given the capacity for adaptation tion 100,000 times greater than that of sex¬ of the phytopathogenic agents (the bacte¬ ual reproduction. A further advantage is ria, viruses, etc., that cause plant disease), that plants obtained from meristems are the useful life of a new variety is estimated The apical meristem is a tiny mass of cells free of pathogenic contaminants, in particu¬ where growth takes place at the tip of a to be a mere five years. lar of viruses, which means that it is possible plant stem. It plays a particularly important Another advantage of certain recently role in plant propagation because it re¬ to regenerate stock threatened with extinc¬ evolved techniques is that they make it pos¬ mains healthy even when the rest of the tion due to diseases that cannot be treated sible to cross-breed species that are too far plant is infected with a virus. In vitro cul¬ in any other way. apart for normal sexual reproduction, thus ture of the meristem of a diseased speci¬ Tropical agriculture has much to gain men makes it possible to generate a new, opening the way for the creation of entirely from micro-propagation. For example, a healthy plant, and allows the rapid produc¬ new plant varieties. single oil palm regenerated from a fragment tion of virus-free planting materials. Be¬ The first major successes were achieved low, sectional drawing of a plant bud of leaf tissue could, within a year, supply by means of vegetative hybridization of shows the apical meristem at centre, pro¬ 500,000 identical, filariosis-resistant plants cereal seedlings. This method, which con¬ tected by enfolding leaf shoots. Meristem producing up to 6 tonnes of oil per hectare sists of cross-breeding between plants by culture calls for particular care in the per year, that is six to thirty times more than choice of culture conditions and nutritive the elimination of self-fertilization, is com¬ the principal oil-producing plants (sun¬ media. paratively easy in the case of allogamous flower, soya, peanut). This same technique cereals, such as maize, in which the male is now being applied to the propagation of leaf shoots organs are separated from the female new varieties of coconut palms. organs and can thus be manually eliminated Another technique which holds great before fertilization has taken place. It is promise for the future is the in vitro produc¬ more difficult with autogamous plants, such tion of haploid plants (plants whose cells as wheat, tomatoes, soya and lupin, in contain a single set of chromosomes). Tra¬ which the male and the female organs are ditional methods of selection are made contained in close proximity within the more time-consuming and complicated flower. Today, this difficulty has been over¬ because of the diploid nature of vegetative come by the discovery of chemical com¬ plants, that is to say, because the cells of pounds which render the pollen sterile. which they consist contain a double set of Many varieties of hybrid cereals and chromosomes, one coming from each pa¬ other plants are now on the market. Gener¬ rent. As a result, some so-called "recessive" ally speaking, fields should be sown with characteristics carried by a chromosome first generation hybrid seed. Hybrid seed may be masked by a dominant homologous usually tends to degenerate and must be chromosome and its presence may only renewed annually. At all events, the world be revealed, through the operation of market for hybrid seed is growing rapidly Mendelian segregation, after several and, according to a recent estimate, will generations. attain a value of $20,000 million by the year This, of course, slows down the work of 2000. the person undertaking the selection. The Other techniques now being developed recent emergence of a technique somewhat are more distant in prospect yet just as similar to micro-propagation has made it promising. One of these is in vitro vegetative possible to overcome this difficulty. This propagation, or micro-propagation, by the technique enables a complete plant to be
  • 7. obtained either from the male gametes, or in regenerating somatic hybrid cells of sev¬ Nitrogen fixation reproductive cells (androgenesis), or from eral plants of agricultural interest such as the female gametes (gynogenesis). Like the rapeseed, chicory and potato. On the other Through its World Network of Micro¬ gametes from which they are derived, these hand, attempts to do the same with sun¬ biological Resources Centres (MIRCENs), plants are haploid. Since they have only one flower, cereals and legumes have so far one of whose priority programmes is set of chromosomes, their genetic charac¬ failed. Nevertheless, there is hope that devoted to the question of nitrogen fixa¬ teristics, whether recessive or dominant, present difficulties will soon be overcome, tion, Unesco is contributing actively to are immediately evident to the person mak¬ at least in obtaining hybrids of varieties of another field of biotechnology that is rich in ing the selection. Haploid plants are usually the same species. promise (see article page 27). infertile, but by treating them with col¬ The great advantage of somatic hybrid¬ The nif genes, which are coded for the chicine, which induces a doubling of the ization is that it makes it possible to transfer fixation of nitrogen, have now been identi¬ chromosomes, a fertile plant is obtained not only the genetic characteristics borne by fied and their structure is on the point of with two sets of identical chromosomes and the chromosomes of the nucleus, but also being fully mapped out. Furthermore, these with phenotypically stable characteristics. those of the specialized parts of the cell genes have been transmitted to non- Another technique used in gynogenesis is to contained in the cytoplasm (the "liquid" nitrogen-fixing organisms such as Proteus fertilize the ovule with irradiated pollen. portion of a cell surrounding the nucleus) vulgaris, Agrobacterium tumefaciens and In China, new varieties of rice obtained such as mitochondria and chloroplasts. Escherichia coli. In principle there is no by androgenesis are being cultivated on sev¬ These latter are the key to processes and reason why they should not also be trans¬ eral millions of hectares of land. Laboratory properties of great importance such as ferred to higher plants and important experiments in gynogenesis are also now photosynthesis, the assimilation of carbon results in this direction can be expected being undertaken on barley, rice, wheat, dioxide, male sterility and resistance to soon. However, the creation of nitrogen- maize, sugar-beet and other species. herbicides, diseases and drought. fixing cereals is a distant prospect still in the Somatic hybridization has paved the way realm of science fiction. High hopes are also being placed in soma¬ tic hybridization, a technique which consists for the newly emerging discipline of plant With regard to plants other than the of fusing two cells whose cell walls have genetic engineering which is concerned with legumes, attention is now concentrated on previously been removed by enzymatic the implantation of specific genes", whether nitrogen fixation by bacteria and fungi treatment. Using this technique scientists of vegetal or other origin, into the genetic which invade their roots either on the root have succeeded in fusing plant cells not only make-up of a plant (see article page 13). surface or by entering their tissue where with other plant cells but also with animal Using these new techniques the nutritional they form nitrogen-fixing nodules. These and even human cells. In most cases, value of the haricot bean, for example, has studies have not yet reached the molecular however, the chromosomes of one of the been improved by the transfer of a gene biology or the genetic engineering stage, fused cells are quickly eliminated and it has from the Brazil nut. but they hold out much promise for tropical only been possible to obtain complete, In Europe, Japan and the United States forestry, sand dune stabilization and the stable hybrid cells from the fusion of cells of America, a number of large multina¬ fight against desertification. from very closely related species. Further¬ tional companies are showing keen interest Finally, mention should be made of stud¬ more, even when stable stock has been in these new techniques of plant improve¬ ies being made in the Philippines and Sene¬ obtained, it has proved difficult to regener¬ ment with a view to competing for the world gal on the use of the water fern Azolla pin- ate a complete plant from such fused cells. market. Nevertheless, this branch of bio¬ nata as a biological fertilizer in rice fields The first success achieved was the regenera¬ technology also offers great opportunities (seethe Unesco Courier, December 1984). tion of the pomato, a cross between a potato for the developing countries. These new In symbiotic association with the blue-green and a tomato. However, the plant is sterile techniques, which they have already algaAnabaena this water fern has the ability and remains no more than a laboratory acquired or can rapidly master, will enable to fix atmospheric nitrogen. Ploughed into curiosity. them to adapt their agricultural production the soil between harvests, this "green fertil¬ More recently scientists have succeeded to meet local conditions and requirements. izer" can increase the crop by over 50 per r The Green Revolution RESEARCH into the selection of new even better adapted and which gave a better end of the 1970s. In the Punjab, farm re¬ high-yield cereal varieties began after yield. In addition to wheat and rice, this venues doubled in 1972, six years after the the Second World War. Wheat and research also concerned millet and sorghum, introduction of new cereal varieties. rice varieties were selected In Mexico and the triticale, maize and several leguminous plant In some regions of Asia where water Philippines respectively, then during the species. resources permitted, the shortening of the 1960s the new strains were used in other In just over a decade, more than half the growing period of new rice varieties allowed parts of the world, and it was later established surface of corn-growing land and one-third of two or three crops to be harvested per year. that they had contributed to a significant that of rlceland in developing countries had The prime beneficiaries of the "Green increase in agricultural yields. been sown with high-yield cereal varieties. Revolution" were the wealthier farmers of In the mid-1960s, following the introduction When the latter are irrigated, and receive ade¬ some developing countries. The countries of of these high-yield varieties Into several coun¬ quate supplies of fertilizer and weed-killer, the Africa south of the Sahara were scarcely tries of Asia and Latin America, the expres¬ yield is two or three times higher than that of affected; only Kenya and Zimbabwe in¬ sion "Green Revolution" was coined to traditional varieties. creased the area of land on which new vari¬ describe the various efforts made to increase The new varieties of wheat were introduced eties of maize were grown. The wheat and rice agricultural production in the developing to India in 1966 and Indian wheat production varieties were not introduced at the same countries by means of these new varieties, had doubled by 1970-1971, when it reached pace as in Asia where the development of especially wheat and rice. The cultivation of 23.4 million tonnes. As a result of local efforts irrigation, adequate fertilizer supplies, and the these crops required the use of pesticides and to improve varieties and a more widespread marketing system of farm produce played an Irrigation in addition to fertilization and sound use of selected seeds, output reached 33 mil¬ important role in the success of the "Green agricultural practices. Cross-breeding be¬ lion tonnes in 1978-1980. From being the Revolution." tween these varieties and hardy local breeds world's second largest cereal importer in Source: Oue//es biotechnologies pour les pays en développe¬ made it possible to obtain cultivars that were 1966, India had become self-sufficient by the ment? by A. Sasson, Biofutur/Unesco, Paris. 1986
  • 8. cent and its effect, which lasts for two years, visiae) and certain anaerobic bacteria, such is equivalent to the use of 60 kilograms of as Zymomonas mobilis, convert the sugars nitrogen fertilizer per hectare. into ethanol with an average yield of 47 per cent, by weight. Several suitable raw mat¬ The cloning erials are available in considerable quan¬ Energy from waste tities at a low price. However, from the of the oil palm Biotechnology's contribution in the field of economic point of view there is one impor¬ new energy sources is today arousing great tant drawback: the ethanol has an inhibiting interest for two reasons: the foreseeable The oil palm (Elaeis guineensisj is culti¬ effect on the micro-organisms that produce vated as a source of oil in the humid tropic¬ exhaustion of our supplies of fossil energy it and the maximum concentration in the al zones of Africa, the Americas and (oil and coal), and the world energy crisis reactors cannot exceed 8 to 10 per cent. As a South-east Asia, where oil palm planta¬ which, since 1973, has weighed heavily on tions cover several million hectares. result, the distillation of bio-ethanol and its the economies of all countries, but par¬ Selection cycles to produce higher-yield¬ complete dehydration, which is essential to ing varieties through sexual reproduction ticularly on those of the countries of the its use as a fuel, are costly operations con¬ were very long, and their results were only Third World. stituting about 60 per cent of the cost perceptible after 15 or 20 years. In the One achievement, which has already price. 1970s, attempts were thus made to perfect been developed on a large scale in a number In Brazil, ethanol fuel is produced from in vitro propagation of the oil palm using of countries, is the production of biogas sugar-cane on a large scale. At present pro¬ Photo © IRHO-CIRAD/ORSTOM, Paris from cellulose and animal and human duction is running at 8.4 million tonnes wastes. This is based on the anaerobic which in energy terms is equivalent to 5.6 digestion of cellulose and nitrogenous million tonnes of super-grade petrol. In organic matter by mixed populations of agricultural terms the yield is 4.7 tonnes per microbes consisting of bacteria that break hectare of sugar-cane per year. down cellulose into organic acids and other At present, the cost price of bio-ethanol bacteria that convert these organic acids exceeds that of petrol by $380 per tonne. In into methane. Brazil, however, the economic motivation Experience acquired in India indicates for producing bio-ethanol is to improve the that the manure from ten cows would balance of payments by reducing imports of provide a daily yield of 1.8 cubic metres of petrol and to provide an outlet for the sugar biogas, which is the equivalent of 1.3 litres industry which has been badly hit by the fall of petrol, enough to cook the food for four in the price of sugar on the world market. people or operate a hundred candlepower Bio-ethanol is arousing great interest lamp for fourteen hours. What is more, the elsewhere for similar reasons. In the United residue constitutes an excellent fertilizer of States, "Biohol", an automobile fuel con¬ a quality far superior to the original taining 10 per cent ethanol produced from manure. maize, has been on the market for several A million of these cheap and simple bio- years. In Western Europe it is planned to gas digesters are in service in India and produce 3.4 million tonnes of bio-ethanol more than seven million are in use in China. annually. The aim of this project is to make Production of biogas on farms can be use of European surpluses of wheat and expected to spread soon to other agri¬ sugar-beet. There is also an ecological cultural areas in which other forms of motivation. Added to automobile petrol in energy are not available. From the ecologi¬ a proportion of 5 per cent, ethanol can cal viewpoint, biogas has the great advan¬ replace the tetraethyl lead anti-knock addi¬ tage that it can replace firewood, thus tive now used in petrol, but shortly to be contributing to the struggle against banned because of its toxic effects. deforestation and desertification. Biogas production is also increasing in Bridging the protein gap the industrialized countries as well as in large towns and heavily populated rural Generally speaking, proteins, or the lack of tissue culture, and since 1981 oil palm areas in general. The main economic gain them , constitute the major nutritional prob¬ plantlets have been produced on a semi- here is that the treatment of waste water lem facing the developing countries. Statis¬ industrial scale at the La Mé research sta¬ and the handling of agro-industrial wastes tics published by the Food and Agriculture tion in the Ivory Coast (1) using a cloning and the animal waste from intensive stock- Organization of the United Nations technique developed by British and French researchers in the 1970s. Photos rearing can be turned to advantage by the (FAO), show that average total protein show some of the stages in the cloning production of methane. Already several consumption per head of population in the process. Fragments of very young leaves urban water treatment plants in Europe developing countries is only half that of the are carefully removed from the tip of a tree meet all their energy requirements by the rich countries. The difference is even more (2) and placed in a nutrient medium where production of biogas. marked with regard to protein of animal calluses develop (3). After going through a origin, average consumption of which in the second and then a third culture medium the calluses evolve into "embryoids" (4) Green gasoline developing countries is 13 grams per comparable to the embryos obtained by day a mere 22 per cent of that in rich coun¬ sexual reproduction. They multiply spon¬ The production of liquid fuels, in particular tries and this falls to 4 grams per day in taneously, and this multiplication is fos¬ ethanol, is another major contribution of the poorest regions of Africa and Asia. tered in a fourth culture medium. A fifth biotechnology in the field of new energy In the developing countries a great vari¬ culture makes it possible for the embryos sources. A large number of agricultural raw ety of agricultural products and wastes lend to develop into young leaved plantlets (5). The shoots are transferred to a sixth materials can be used for the production of themselves to the production of single-cell medium in which roots are induced (6), ethanol by fermentation, including the edible protein. These include, in particular, while in a seventh medium entire young sucrose in sugar-cane, sugar-beet and ligno-cellulosic matter which is available in plants are obtained for planting in soil (7). molasses, the starch from cereals, manioc large quantities at a low price. According It takes about 3 months to obtain a 12 cm and potatoes, and the inulin from Jerusalem to the United Nations Environment shoot from an embryoid. artichokes. Programme (UNEP), the world crop of Brewer's yeast (Saccharomyces cere- cereals produces annually 1,700 million L 8
  • 9.
  • 10. Powerful protoplasts Techniques for the cloning of plants are now so refined that a single cell removed from the body of a plant can be cultured in the laboratory and then induced to re¬ generate a complete individual plant. Drawings at left and below are a schematic representation of the cloning process used by Prof. James F. Shepard and his colleagues at Kansas State University to regenerate a complete potato plant from protoplasts (living cells stripped of their outer wall) prepared from leaf cells. Small terminal leaves are first removed from a young potato plant (1). The leaves are placed in a solution containing a combina¬ tion of enzymes capable of dissolving the cell wall to produce protoplasts (2). The solution also causes the protoplasts to withdraw from the cell wall and to become spherical, thereby protecting the proto¬ plasm during the disintegration of the walls (3). The protoplasts are next grown in a culture medium (4) where they divide and begin to synthesize new cell walls (5). After 2 weeks of culture in these con¬ ditions, each protoplast gives rise to a clump of undifferentiated cells or micro- calluses (6). These microcalluses develop into full-size calluses in another culture medium (7) and their cells begin to dif¬ ferentiate, forming a primordial shoot (8). The shoot develops into a small plant with roots in a third culture medium and is then tonnes of straw, to which can be added planted in soil (9). Under appropriate con¬ some 127 million tonnes of bagasse from ditions protoplasts from 2 different plants sugar-cane and pulp from sugar-beet. At can be fused to form a cell possessing present, the main obstacle to their use for genes of plants which cannot be crossed using classic methods. The fused proto¬ the production of proteins is the lack of plasts of some species can be grown into sufficiently active microbial strains for this plants in a process known as somatic specific purpose. Recently achieved labora¬ hybridization. tory results suggest that this problem will soon be overcome. Cuba is, at present, the only developing country producing single-cell edible protein from agricultural raw material. Eighty thousand tonnes of forage yeasts for use as animal feed are produced annually from sugar-cane molasses. The Cuban example will probably soon be followed in other countries, such as India, where molasses is also available at a low price. 10
  • 11. 33^ yj. © For a long time now Western Europe has Born in Europe some thirty years ago, this Protein enrichment by fermentation is a branch of biotechnology that could help been producing single-cell edible protein branch of biotechnology has developed to some developing countries increase their from various agro-industrial wastes such as the point where there are factories with a protein resources. Microbial fermentation lacto-serum (80,000 tonnes per year) and production capacity of 100,000 tonnes per of such crops as manioc, which contain the sulphite liquors used in paper-making year. much starch and relatively little protein, (25,000 tonnes per year). As with biogas, The oil treatment processes make use of yields a product with a substantially high¬ the main economic incentive for this pro¬ yeast micro-organisms (Candida lipolytica er protein content. The banana is a fruit to duction is the elimination of the cost of which this process could be applied, and and Candida tropicalis) which are derived several banana-producing countries are handling potentially polluting wastes. It is from diesel oil or from paraffin, previously investigating the possibility of using in to be expected that the same will happen extracted from crude oil, and having a yield this way the high proportion of fruit re¬ soon in the developing countries where of 100 per cent by weight. In the case of jected for export and usually wasted. increasing industrialization is making pro¬ methanol, chemically derived from natural Above, harvesting bananas in Martinique. tection of the environment an ever more gas, the biomass produced is that of bacteria urgent necessity. such as Methylophilus methylotropha whose One of microbiology's most promising yield on this substrate is of the order of 50 contributions to the problem of edible pro¬ per cent, by weight. The methanol treat¬ teins is their production on an industrial ment processes make use of specific meth¬ scale from oil, methanol and natural gas. ane-eating bacteria (Pseudomonas meth- 8 After J.F. Shepard in Scientific American, New York, 1982 11
  • 12. ylotropha or Methyiococcus capsulatus) in tein-rich microbial biomass and residual is too low for it to be used as animal feed, is conjunction with other species whose task is agricultural raw material whose nutritional a complete write-off. For a number of Cen¬ to prevent the inhibition of the bacteria by value is thus enriched. This relatively sim¬ tral American countries which export sev¬ intermediate accumulation of methanol. ple technology has the advantage that it can eral million tonnes of bananas annually, the Very large-scale experiments with the be used both on a large industrial scale and prospect of recuperating wastage on this products thus obtained from oil and meth¬ in small, inexpensive production units scale by use of the fermentation process is anol have demonstrated conclusively their located in rural communities. This means clearly of the greatest interest and this high nutritional value and complete that high-quality edible protein can be pro¬ possibility is being actively investigated in innocuousness. Up till now, these edible duced from a wide range of agricultural raw Mexico, Guatemala and the West Indies. proteins have been marketed exclusively as materials that are too costly or available Finally, the third major contribution that animal feed, but preliminary studies have locally only in quantities too small for use biotechnology has to offer to the solution of shown that there is nothing to prevent their with standard single-cell edible protein pro¬ the world problem of edible protein is the being used directly as food for humans. duction methods. industrial production of amino acids as a Following the first oil crisis of 1973, pro¬ In all the tropical regions, manioc (also complement to plant proteins. Many such duction of single-cell edible protein from oil known as cassava) is the chief agricultural proteins, in fact, are only of limited nutri¬ and from methanol slowed down in West¬ raw material potentially available for pro¬ tional value because of their lack of certain ern Europe due to the increased cost of the tein enrichment. Cultivated throughout essential amino acids which man and other raw material. In Eastern Europe and in the Africa, in Asia and Latin America, the mono-gastric animals (including pigs, USSR, however, it has developed consider¬ world production of manioc is of the order young ruminants and poultry) are unable to ably and now amounts to some 3 million of 100 million tonnes. Very rich in starch, synthesize and therefore must find in their tonnes per year. but containing practically no protein, man¬ food. This is the case in particular of lysine, This branch of biotechnology is of ioc is used above all as a supplementary which is the amino acid in which cereals are obvious interest to those developing coun¬ energy food. Furthermore, although under most notably deficient and lack of which is tries that are producers of oil and natural good conditions it can yield 50 tonnes per the main cause of malnutrition in the Third gas, since these raw materials are available hectare and over, it is normally only culti¬ World. Almost all the amino acids used as a to them in large quantities at prices well vated on small patches of land using rudi¬ complement to plant proteins are obtained below the world market price. The Organi¬ mentary methods with low productivity. by fermentation using hyper-productive zation of Arab Petroleum Exporting Coun¬ At present, the only country in which bacterial strains selected genetically. tries, for example, proposes as a first step to manioc cultivation has been developed Apart from methionine, which is produce 100,000 tonnes of single-cell edible rationally is Thailand, which exports 7.5 basically intended for use in animal feed, protein a year, either from oil or from meth¬ million tonnes of manioc root to the Euro¬ lysine is the only amino acid produced in anol, and it estimates the potential market pean Community each year. large quantities (40,000 tonnes per year). It in the Middle East and in the Maghreb at Starting with dried manioc with an initial has been estimated that the world deficit in more than a million tonnes. It should be content of 90 per cent starch and less than 1 lysine, most marked in Africa and the Far pointed out that this amount of protein per cent protein, fermentation with an East, is 136,000 tonnes for human food and could be obtained from 0.1 per cent of their amylolytic mould (Aspergillus hennebergii) three times that figure for animal total oil production. yields a product containing 20 per cent well- foodstuffs. As things stand at present, the Protein enrichment of foodstuffs by fer¬ balanced proteins and 20 to 25 per cent cost price of lysine is still too high to ensure mentation is another promising prospect. residual sugars. In this way manioc can satisfaction of Third World needs and to Application of modern biotechnological provide nearly 2 tonnes of protein per hec¬ compete with soya in animal feed. The sit¬ methods to this practice, which is tradi¬ tare, that is, three times more than can be uation is the same for other amino acids, in tional in Africa and the Far East, seems set obtained from the cultivation of soya or particular threonine and tryptophan, fair to provide the developing countries other leguminous plants. which, after lysine, are the chief elements with a substantial increase in their protein The banana too is a raw material with a lacking in plant proteins. However, it is resources for human and animal consump¬ bright future. In the collection centres of reasonable to assume that, thanks to tion. exporting countries, 20 to 30 per cent of the genetic engineering, substantial progress The end product of this fermentation pro¬ fruit gathered is rejected. This rejected will soon be made. cess is a directly consumable mixture of pro fruit, whose protein content at 1.1 per cent JACQUES C. SENEZ, French biologist and uni¬ versity teacher, is a former Secretary-General of the Unesco-sponsored International 'Cell Re¬ search Organization (ICRO) and a consultant member of the Protein Advisory Group of the United Nations. A past Secretary-General of the International Union of Microbiological Societies (IUMS), he is the author of a number of studies on microbiology and bacterial biochemistry. In the late 1960s he initiated the production of Single Cell Protein (SCP) from petroleum. 2 Many developing countries are engaged in I programmes to harness the techniques of e biotechnology for national development. § Left, fermenters of a Cuban factory pro- $ ducing single-cell edible protein from © molasses. The installation produces some % 40 tonnes of protein a day for use as anim- £ a/ feed. 12
  • 13. by Bernard Dixon The gene revolution GIVEN the mixture of benefits and which they are part. The astronomically problems spawned by the first long DNA molecule can be subdivided into Green Revolution two decades regions genes which determine particu¬ lar characteristics. Recombinant DNA is ago (see box page 7) , it is not surprising that both optimism and apprehension surround the name given to the product when a piece the application of genetic engineering now of DNA from one organism is combined to agriculture tomorrow. Mixed reactions artificially with that from another. are appropriate, because those develop¬ Genetic manipulation of this sort is the ments focused upon so-called recombi¬ basis for the boom that has occurred during nant DNA are destined to have even the past decade in biotechnology. Such more far-reaching effects than the tech¬ activities were, of course, possible pre¬ niques deployed in the first revolution. viously. Some, like the art of fermenting Photo above shows the distinctive knot¬ sugar to make alcoholic drinks, are almost Today's new wizardry could undoubtedly like growths or nodules which form on the as ancient as Man himself. Others, includ¬ transform agriculture throughout the roots ol legumes (plants of the pea family) world. At the same time, its precision in ing the first mass production of antibiotics, when they are infected by certain bacteria. These bacteria, known as rhizobia, take modifying living cells offers a stern chal¬ were developed earlier this century. But all nitrogen from the air and change it into lenge to our prudence and wisdom. of these processes were based on organisms forms the plants can use. One important At the centre of the stage is deoxy¬ as they occur in nature albeit with other, aim of research in biotechnology is to ex¬ equally natural, methods being used to ribonucleic acid (DNA), the material which tend this process of nitrogen fixation to carries in coded form the hereditary instruc¬ select high-yielding strains. other crops by incorporating nitrogen-fix¬ tions responsible for the behaviour of cells The arrival of recombinant DNA, how¬ ing genes into their genetic heritage. The goal is proving difficult to attain. and the plants, animals or microbes of ever, has altered the rules profoundly. It 13
  • 14. has already greatly enhanced our specificity pieces of DNA in this way, genetic engi¬ teria and gives the plants the capacity to and power in tailoring living organisms for neers are beginning to create pedigree produce a toxin that is lethal to insects. The beneficial purposes. In future, it will extend microbes for a wide range of new purposes inbuilt insecticide makes the plants resistant our range of options much further. in agriculture, medicine and industry. to insect attack and does not, of course, The breakthroughs which have led to this Although genetic manipulation is taking have to be applied repeatedly. Some plants historic watershed in the fabrication of longer to perfect in plants, several tech¬ can mobilize defences against virus infec¬ novel plants and microbes happened during niques are now emerging. The most useful tion through a process analogous to immu¬ the early 1970s. The key discoveries were so far is based on Agrobacterium tumefa- nization in animals, and this suggests made by molecular biologists who learned ciens, a bacterium that causes crown galls another route for genetic alteration. Incor¬ how to splice into bacteria genes which they on many flowering plants. It contains a poration of one virus gene into tobacco has had taken from other bacteria, and even tumour-inducing (Ti) plasmid which is helped to protect this plant against subse¬ from totally unrelated animal or plant cells. responsible for triggering the disorderly quent inoculation with the entire virus. They first found out how to locate the par¬ growth that appears as ugly galls. Genetic Another development concerns ticular gene they wanted among the count¬ engineers have learned how to delete the Ti weeds a major limitation on crop hus¬ less numbers on the DNA of one organism. plasmid's tumour-inducing genes and use it bandry in most countries. Although weeds Then they used natural catalysts called as a vector with which to carry new genes can be combatted using selective her¬ enzymes to cut out that gene and "stitch" it into plants. bicides, these often impair the growth of the into a vector. This is usually a virus or a A serious drawback so far is that while A. crop too. It is now possible, however, to plasmid (a piece of DNA that replicates tumefaciens infects potatoes, tomatoes, and introduce resistance genes into tobacco and independently from the nucleus, the main many forest trees, it does not normally petunia. One such manipulation results in repository of DNA). The vector became a attack the monocotyledons such as cereals, the synthesis of enzymes in the plant that vehicle for ferrying the selected DNA frag¬ which are prime targets for genetic im¬ are no longer sensitive to the inhibitory ment into the recipient. Once inside its new provement. Progress is being made, action of the herbicide glyphosate. Com¬ host, the foreign gene divided as the cell however, and recent research indicates that mercial companies now plan to market a divided leading to a clone of cells, each rice in particular can be manipulated using package containing both herbicide and containing exact copies of that gene. the Ti plasmid. Alternative vectors and resistance seed. Because the enzymes used for genetic other methods of transferring genes are also Some 70 per cent of the world's intake of engineering are highly specific, genes can being developed. One exciting possibility is dietary protein consists of cereal grains and be excised from one organism and placed in to use an electric current to promote the seeds of legumes. On their own, neither another with extraordinary precision. Such incorporation of foreign DNA. This works cereals nor legumes can provide a balanced manipulations contrast sharply with the with maize cells, though scientists still have diet for human consumption, because the much less predictable gene transfers that to persuade the cells to develop into whole "storage proteins" they each contain are occur in nature. They also make it possible plants. deficient in one or more amino acids. Now, to splice genes that would be unlikely to One gene that has been transferred into added to analyses of the proteins in both come together naturally. By mobilizing tobacco by A. tumefaciens comes from bac cereals and legumes, we have precise infor- How to recombine DNA Drawing shows how a micro-organism (in this case a bacterium) is manipulated to make it synthesize a desired substance. (1) A bacterium contains a plasmid, which is a circular piece of DNA. This plasmid is isolated (2) and, with the help of a restriction enzyme, opened in a precise spot (3). Meanwhile, with the help of other restriction enzymes, the gene for synthesis of the desired substance is isolated from the DNA of another organism (4). Still using enzymes, this gene is grafted onto the previously opened plasmid (5). The plasmid is re-introduced into a bacterium (6). The manipulated bacteria are put into a culture, where they synthesize the desired substance. (7) o ó 14
  • 15. mation about the DNA sequences coding for them. This knowledge may well lead to methods of altering those sequences or introducing new genes that code for a more balanced spectrum of amino acids. The world's energy and food supplies rest upon the ability of green plants to convert atmospheric carbon dioxide into carbo¬ hydrates, fats and proteins, using light from the sun. Unfortunately, the mechanism by which they consume carbon dioxide is inef¬ ficient in those plants, such as wheat, barley and potatoes, that are cultivated in tem¬ perate climes. Oxygen in the atmosphere interferes with the first enzyme involved in the assimilation of carbon dioxide. Consid¬ erable efforts are now being made to alter the DNA sequence of the gene coding for this enzyme, to prevent the deleterious action of oxygen. Other researchers are try¬ ing to introduce into temperate zone plants certain genes taken from maize, which has a more efficient mechanism of carbon dioxide uptake. In nature this mechanism appears to operate only at higher temperatures, but there are hopes of "switching it on" in cooler areas. Another atmospheric gas is the subject of parallel efforts to make plants more effi¬ cient. Nitrogen constitutes 80 per cent of the air, yet plants cannot use the gas directly. Hence the heavy dependence of modern intensive agriculture on fertil¬ izers nitrate, ammonia or urea syn¬ thesized by the chemical industry. Natural nitrogen fixation depends in part on rhizobia, bacteria that live symbiotically with legumes such as peas, beans and clover. The bacteria grow on sugars provided by the plant, and are maintained in characteristic nodules on the plant. There they convert nitrogen directly into ammonia, leading in turn to the synthesis of plant proteins. Molecular biologists have now isolated and characterized several of the genes required for nitrogen fixation. They have found, however, that many more bacterial and plant genes are involved than they first fixation. Drought resistance which depends A key area in biotechnology research is imagined. This makes the manipulation of on a reduced area of leaf surface, for exam¬ concerned with the development of tech¬ those genes correspondingly more difficult. ple, may be caused by the interaction of niques for isolating genes of one plant and So it will be some years before we can enjoy multiple genes. introducing them into another as a means of endowing the host plant with new char¬ the cost and energy savings that should Microbes that contribute to healthy plant acteristics such as higher protein content accrue by providing crops such as wheat and growth are also on the drawing board for or resistance to pests. One promising maize with the ability to fix their own genetic engineering. One possibility being technique for transferring genes uses nitrogen. examined is the production and deliberate Plasmids (small pieces of genetic material) Drought and high temperatures are release of rhizobia that fix nitrogen more from a bacterium which causes tumour unwelcome to all plants, despite being bet¬ efficiently than natural strains. Other bacte¬ growths when it infects certain plants, above. It is possible to delete the plasmid's ter tolerated by varieties that have evolved ria capable of forming nitrogen-fixing part¬ tumour-inducing genes and use the plas¬ in such environments. Desiccated soils also nerships with wheat and maize are also mid to ferry new "useful" genes into often contain high levels of salts and metal¬ being considered. A third type of prospect plants. Genes of a bean protein have been lic elements, which are toxic to plant follows the discovery by researchers at the transferred to the sunflower using this method. growth. Genetic engineers would dearly University of California, Berkeley, that like to fabricate plants resistant to such frost damage to strawberries is triggered by stresses, but success is unlikely in the near bacteria which act as nucleii for the forma¬ future. Before being able to identify the tion of ice crystals on leaves. The cause is a relevant DNA sequences for transfer particular bacterial protein, the gene for between plants, they require a far better which the California biologists have learned understanding of the many ways in which to delete. They believe they can prevent the plants respond to their environment. An extremely costly frost damage by spraying additional problem may be the involvement crops with this "ice minus" strain , which will of several different genes, as with nitrogen outgrow the natural flora. 15
  • 16. The use of genetic engineering in food production offers many potential advan¬ tages. At the same time, questions have been raised about the possible risks in¬ volved in releasing genetically modified living organisms into the environment. One case which led to widespread debate and concern in the United States arose from the development and use of geneti¬ cally modified microbes known as ice- minus bacteria to protect strawberries from frost damage. In photo, the leaf at left has been treated with ice-minus bacteria. The leaf at right froze when dipped into supercooled water. I © Genetic engineering holds considerable in America, even natural weeds can cause about an organism's potential safety or per¬ promise too in the improvement of "biolog¬ considerable havoc. formance in nature. The scientific con¬ ical insecticides", microbes that attack pests The prospect of genetically engineered sensus is now for a gradual approach, a and have enormous ecological advantages crops themselves becoming weeds is priori evidence about a released organism's over their chemical counterparts. Bacillus remote, however, because crop varieties likely behaviour being used as the basis for thuringiensis, for example, has been used cannot compete well with other plants when successively larger trials during which expe¬ for many years to combat nuisance species, left unattended. The inherent difficulties of rience and confidence are gathered about but it and similar bacteria and viruses may mobilizing plant genes also make it unlikely how it actually does behave. well be made more powerful by recombi¬ that unwelcome varieties will be produced There is one other argument against the nant DNA. One possibility is illustrated by accidentally. And there is always the pos¬ much-publicized view in the USA that the pine moth, which damages lodgepole sibility of destroying by fire or other means organisms carrying recombinant DNA pine trees in northern Britain. In other parts an engineered plant, released initially in a should never be released for purposes such of the country, the moth is controlled natu¬ defined area, that did create problems. as pest control. One third of the world's rally by a baculovirus that infects the cater¬ Nonetheless, field trials with novel plants, crops are now lost through infection and pillars. There are now plans to make the particularly crops able to cross-fertilize with pestilence. It would be foolhardy not to virus more efficient at killing caterpillars weeds, need to be very carefully monitored. make use of an ecologically acceptable tech¬ and to release it in the pine plantations. The Greater caution still is required with engi¬ nique capable of achieving even a modest first experiments are being carried out with neered microbes, which would be broadcast reduction in that toll. a virus that has been altered only by having in astronomical numbers and be impossible a "marker" introduced into a non-coding to trace in their entirety should anything go region of its DNA. This will allow awry. But it is reassuring that no health, researchers to follow the virus's distribution environmental or other dangers have been and survival after spraying. If all goes well, BERNARD DIXON, British science writer and caused by recombinant organisms since consultant, is European editor of The Scientist the virus may be given a genè allowing it to they were first fabricated over a decade ago. magazine and was formerly (1969-1979) editor synthesize an insect-killing toxin. The Moreover, biologists now agree that there is of the British scientific ¡ournalTUe New Scientist. potential for this technique in other coun¬ no significant difference between a microbe Notable among his published works are Magnifi¬ tries, against other destructive insects, is that has received a new piece of DNA cent Microbes (1976), Invisible Allies (1976) and clear. (with G. Holister) Ideas of Science, Man and through artificial manipulation and one that Medicine (1986). The safety of laboratory and industrial has acquired the same DNA fragment activities using engineered organisms is through natural mechanisms of gene trans¬ based on the idea of containment. Facilities fer. Most experts argue that recombinant are graded according to the degree of risk. DNA manoeuvres are intrinsically safer, New questions arise, however, when mi¬ because they can be vastly more precise and crobes and plants are to be introduced into selective. Certain laboratory manipulations the environment. There is concern, for are ruled out anyway by a priori predictions example, that weeds may be created acci¬ that they would generate hazardous recom¬ dentally and be inordinately difficult to binants. eradicate. If such a plant were drought- Many researchers believe that tests with resistant, herbicide-resistant, and frost-tol¬ recombinants should always be restricted to erant, it might spread quickly over large closed environments such as greenhouses. areas of agricultural land and be very diffi¬ But these "microcosms" can never simulate cult to eradicate. As illustrated by the the richness of the natural biosphere. So Kudzu plant in Asia and the water hyacinth they can never provide conclusive evidence 16
  • 17. Tomatomation Japan's high-tech food factories by Koichibara Hiroshi THE harnessing of high technology to Light, temperature and humidity are com¬ '85 (see the Unesco Courier, March 1985). vegetable farming may be about to puter controlled in this vegetable factory This was a major success for a hydroponic in a Tokyo suburb. High electricity con¬ culture system developed after many years trigger a new agricultural revolu¬ sumption is a drawback. tion in Japan, where some large manufac¬ of research by a Japanese agronomist, turers are already offering fully automatic Nozawa Shigeo. The growth of the plant "factories" in which vegetables are grown in was accelerated in a nutritive solution which a computer-controlled artificial environ¬ replaced soil and in an artificially controlled ment. In their use of automation and high development is hydroponics, the cultivation environment. As a result the plant pro¬ technology these facilities resemble auto¬ of plants in nutritive solutions. Factory duced more than 13,000 tomatoes during mobile or electronics plants, but instead of farms are air-conditioned, and high-pres¬ the six months of the Expo. automobiles or video tape recorders their sure sodium lamps provide twenty-four- Daiei, Japan's biggest supermarket mass production lines produce fresh vegeta¬ hour-a-day illumination. The density of car¬ chain , has installed a factory farm next to its bles, regardless of season or climate. bon dioxide, oxygen, temperature and store in the Tokyo suburb of Fanabashi. Strictly speaking, today's factory farming humidity are controlled by a computer to This experimental facility, constructed in technology is based not on biotechnology maintain an optimum growing environ¬ co-operation with Hitachi Ltd. to grow let¬ but on applying industrial production man¬ ment. tuce for sale in the adjoining supermarket, agement techniques to conventional agri¬ The hardware used in this process is not may be the world's first commercial factory cultural engineering. The aim is to use new. It is readily available from manufac¬ farm using full automatic hydroponic cul¬ artificially controlled environments to grow turers of electrical consumer goods, and this ture technology. The system produces some plants rapidly and efficiently rather than may be the reason why Japanese electrical 130 heads of lettuce and other green vegeta¬ improve the adaptation of plants to natural conglomerates are active in this field. Com¬ bles per day (some 47,000 per year) on a conditions. Such ideas have already been panies in Denmark, the United States and floor space of no more than 66 square applied to poultry farming, egg production Austria are also experimenting with vegeta¬ metres. Grown from seed, the lettuce is big systems, and even the production of foie ble factories but for the moment the Jap¬ enough for harvesting in only five weeks, gras. Factory farms may thus make a big anese seem to be leading the field. 3.5 times faster than plants cultivated using In 1985, a "supertomato" plant was dis¬ conventional methods. impact on conventional agriculture since they provide planned cultivation regardless played in the Japanese government- In this futuristic factory, the sun is of weather, season, climate or soil. sponsored pavilion at an international replaced by artificial twenty-four-hour The essential element in this new exhibition held in Japan, Tsukuba Expo. lighting, soil with nutritive solution and 17
  • 18. farmers with a micro-computer. The crop is metres and a construction cost of $60,000. tasty and free from pesticides and her¬ Since May, each factory has been producing bicides, and is in great demand, regardless 120 heads of lettuce a day. Experiments are of the price tag, which is double that of being carried out on the cultivation of other conventionally grown lettuce. vegetables such as tomatoes, cabbage, In Mitsubishi Electric's Amagasaki labo¬ asparagus, melon and green peppers. In the Trays of growing lettuce were rotated up ratory, a prototype food factory assembly case of JNR, electric power supplied by its and down on chain conveyors in this line succeeded in growing lettuce seedlings own power plants can be efficiently used at vegetable factory installation shown in the from 2 grams to 130 grams in 15 days 6 night when demand is low, and open spaces Japanese Government pavilion at Expo times faster than the natural growth rate. beneath the overhead railway or aban¬ '85, an international exhibition held at Tsu- kuba (Japan) in 1985. The lettuce were With specially developed fluorescent doned tunnels can be utilized as sites. grown in liquid nutrients, using the tech¬ lamps, the photosynthetic ratio is said to be Artificial lighting and computers are not nique known as hydroponics. The 24- better than that of the sun. Sprouts cloned essential elements in factory farming. hour-a-day lighting, carbon-dioxide-rich from the tissues of mature plants start at one Hydroponic food factories can be installed atmosphere and constant temperature end of a conveyor and move along at the in developing countries where food facto¬ helped the lettuce to reach maturity in 20 rate of 20 centimetres a day. ries may be most needed. Matsushita Elec¬ days, 4 to 5 times faster than normal. The moving conveyor belts ensured that every In March 1986 Japanese National Rail¬ tric has, for example, installed a vegetable plant was exposed to the same amount of ways (JNR) built two experimental vegeta¬ factory with minimal automation in the heat and light. ble factories, each with a size of 50 square Maldives. The system, which has a plastic 18