VIRIOLOGY

1. History of Plant Virology

2. Viruses and organisms confused
with viruses
 752 BC- Ref. in poem by one of the Japanese
Empress named Koken in which she described the
yellow leaf symptoms of Eupatorium.
 1576, Carolus Clusius -Tulip color breaking- is the
oldest known example of virus disease
 1692- Yellow stripe of Jasmine was found to be
caused by Jasmine mottle virus.
known in
 1791- Peach yellows was observed in USA
 1869- Abutilon leaf variegation was
France and Belgium.
 Seventeenth century – “tulipomania”

3.  1882-1886: Actual era of Plant Virology started with
scientific investigation by Adolf Mayer
 1886- Adolf Mayer – infectious sap from tobacco induce
disease; gave term Mosaikkrankheit for mosaic
 1892 Ivanowski – Sap retained infectivity even after
filtration through chamberland porcelain filter,
doubted toxin produced by bacterium as cause.
 1893-94 Hashimoto, a Rice grower in Japan suspected
the relation between rice leaf hopper and rice dwarf
disease- so is considered as first evidence of vector
transmission (Later established by Fukushi).
 1898 M. W. Beijerinck– in Netherland finally established
the cause of tobacco mosaic disease and named the
agent as “Contagium vivum fluidum”- gave the term
Virus. Published paper “ Uber ein Contagium vivum
fluidum als Ursache der Fleckenkrankheit der
Tabaksblatter” ----- called
Father of Plant Virology

4.  1904- Baur experimentally proved that Abutilon
variegation is transmitted by grafting not by sap.
 1923- Schultz & Murphy identified Aphids as vector
of viruses.
 1928- H. Purdy Beale – TMV infected plants
contained antigenic material, opened the door in
development of plant virology
 Gratia (1933)- plants infected with diff. viruses
contain diff. antigens
 Chester (1935-36): serological differentiation of
TMV & PVX strains
 1929 Holmes– “Local lesion assay”
 1929- Mckinney observed the phenomenon of cross
protection
 1931- K.M. Smith – Use of indicator plants in virus
studies, helped in purifying the virus.
 1932- Knoll & Ruska invented Electron Microscope.

5. 1935 W. M. Stanley– “Isolation of
crystalline protein possessing the
properties of TMV”; Shared Nobel prize
1946
1936 Bawden and Pirie – reported that
TMV contains nucleoprotein (5%)
1937 Best- finally confirmed
nucleoprotein nature of TMV
1937- Kunkel showed that the Aster
yellows virus multiplies in its leaf hopper
vector.
1939 -Kausche, Pflankuch & Ruska– were
the first to observe TMV under electron
microscope

6.  1940- Fukushi– Transovarial transmission of rice dwarf virus
1944 Williams and Wycoff– Metal Shadowing that enabled the
detail of virus particles
1949-Markham & Smith found that the purified Turnip yellow
mosaic virus contained two types of particles one contained 35%
RNA and were infectious where as other had no RNA thus not
infective.
1951- K. Brakke developed the method of density gradient
centrifugation of plant viruses.
1952- Hershey & Chase demonstrated the infection behaviour
of bacteriophage and showed that only DNA enter the host cell
and protein remain outside

7.  1955- Frankel Conrat & Williams reconstituted the
virus TMV
 1956- Gierer & Schramm (Germany( & Frankel
Conrat showed that only nucleic acid of TMV is
infective and protein coat does not have any
role in infection.
 1956- Krick & Watson gave the general theory of
structure of capsid of virus; the cp made up of
numerous identical subunits as helicle rods or
spherical shell.
 1957- Brandes developed leaf dip method of
electron microscopy
 1958- Bancroft & Kaesberg observed that Alfalfa
mosaic virus contain multiple components.

8.  1960-Teakle made a significant observation that
fungus Olpidium
TNV can be transmitted by
brassicae- a fungus virus vector
 1960- Anderer et al., & Tsugita et al., were the first to
develop the full amino acid sequence of TMV
protein coat (158 aa units).
 1959 Horne– Negative staining of modern day
electron microscopy
 1962- Kassanis– coined the term Satellite virus,
associated with TNV
 1963- Black & Markham demonstrated that wound
Tumor virus contain dsRNA
 1996,1968- Lister discovered the bipartite genome of
TRV by sucrose density gradient centrifugation.
 1967- Doi et. al.; Ishiie et. al.,– MLO in Mulberry dwarf,
aster yellow and potato witches broom
 1968- Shepherd et al., observed that CaMV contain DNA

9. 1970– Harrison et.al. mitochondria is
concerned with the replication of Tobacco
rattle virus; Classified the plant viruses into
16 groups (1971); coined the term
Geminiviruses (1976)
1970- Taylor and Robertson Nematode
transmission
 1971– T. O. Diener: PSTVd – Viroid
1971– Lane and Kaesberg brome mosaic
virus, has split genome
1972- Davis et al. Spiroplasmas

10.  1973- Goheen et al. observed RLO’s – alfaalfa
dwarf & Pierce disease of grapevine.
 1975– Kohler and Milstein “Hybridoma
technology” in monoclonal antibodies
production – Nobel prize in 1984
 1976 – Voller et. al.: developed ELISA
technique
 1977- Clark & Adam: used ELISA in Plant
virus detection
 1977- Harrison et al. coined the term gemini
virus ; transmitted by white fly and have
dsDNA

11. 1980- Frazier and Converse– genome sequence
of ds DNA of CaMV (8000bp sequence).
1982- Keese and Symons– discovered virusoids
1984- Prusiner- discovered Prions in animals:
Nobel Prize in 1997 in Medicines
1986- Powell-Abel et al– C.P. mediated
resistance in TMV.
1989- Hiatt et al., reported that transgenic
tobacco can be induced to produce antibodies

12.  1991- Gallitelli et al. - commercial application of
cross protection (Tomato-CMV; 95% protection)
 Maxwell (1993) – determined the complete
nucleotide sequence of bean dwarf mosaic virus
 Beachy et al. (1997) – elucidated the mechanism of
coat protein mediated resistance.
 2001- Li et al., reported the role of proteins present
in the head tissue of aphid vector in the
transmission of the virus- they found two proteins
as receptor of BYDV; they act as sensors and if
absent in any aphid no transmission occurs

13.  2004- Boorod et al. established that single
chain antibodies for a viral RNA dependent
polymerases confer resistance to three
viruses of Tombusviridae- type member
Tomato bushy stunt virus.
 2006- A.N Fire & C.C. Mello were awarded
Nobel Prize for their work RNA interference-
Gene silencing by dsRNA.

14. Phytopathological classics
1. Fabricius – Attempt at a Dissertation on the Disease
of plants. Ravn (1774)
2. Fontana – Observation on Rust of Grain 1767. Pirone
(1932)
3. Millardet – the discovery of Bordeaux Mixture 1885.
Schneiderhan (1933)
4. Woronin – Plasmodiophora brassicae, the Cause of
the Cabbage Hernia 1878. Charles Chupp (1934)
5. Tillet – Disseretation on the Cause of the Corruption
and Smutting of the Kernels of Wheat in the Head (
and on the means of preventing these untoward
circumstances) 1755. Humphrey (1937)
6. Prevost – Memoir on the Immediate Cause of Bunt or
Smut of Wheat, and on the Prevention of Bunt
1807. Keitt (1939)
7. Mayer (1886), Ivanowski (1892), Beijerinck (1898) and
Baurb (1904) – three early papers on tobacco mosaic
and one on infectious variegation. James Johnson
(1942)

15. 8. Berkeley – Observations, Botanical and
Physiological, on the Potato Murrain 1846. also
includes selections from Berkeley’s “Vegetable
Pathology” made by the Plant Pathology Committee of
British Mycological Society.1948
9. Targioni Tozzeti – True Nature and Sad Effects of the
Rust and Other Maladies of Wheat and of Oats in
the Field1767. Tehon (1952)
10. Bassi – Del Mal del Segno 1835. Yarrow (1958)
11.De Bary – Investigations of the Fungi and the
Diseases of Plants Caused by Them With Reference to
Grain and Other Useful Plants 1853. Arny and Moore
(1969)
12. Hartig – Important Diseases of Forest Trees 1874.
detailed report which established the microbial basis
for wood decay. Merrill et.al.,(1975)

16. 13.Fischer/Smith – The Fischer Smith
Controversy: Are Their Bacterial Diseases of
Plants? 1899. Seven articles depict vthe
classic and bitter debate regarding the
existence of bacterial diseases of plants.
Cambell (1981)
14. Ando/ Fukushi/ Storey – Viruses In Vectors:
Transovarial Passage and Retention.
Classic papers on plant viruses and their
insect vectors 1986.
15. Dutch Elm Disease – Original 11 Articles. That
laid the foundation for studying the
devastating disease. Research by 7 female
Dutch scientists from 1920 - 1935