Genetics and cytogenetics of SACCHARUM OFFICINARUM

UNIVERSITY COLLEGE of AGRICULTURE
ISHTIAQSHARIQ@GMAIL.COM 2

A Presentation By
Ishtiaq Shariq
ISHTIAQSHARIQ@GMAIL.COM
Roll #: 2
B. Sc. (Hons.) 6th Semester
Plant Breeding and Genetics
3

• BIOLOGY
• ECONOMIC IMPORTANCE
• GENETICS AND CYTOGENETICS
• TECHNIQUES
• SOURCES
TABLE OF CONTENT

BIOLOGY
6

• Major world crop
• The Saccharum species are extremely complex
allopolyploids.
• S. officinarum 2n = 80
• Supplying sugar and energy.
• Grass family
• Tropical and subtropical
• Domesticated sweet cane of New Guinea and
South Pacific
• Perennial grass growing 2–6 meters high

• Not tolerant of frost.
• The genome of modern cultivated sugarcane
is large and complex, highly polyploid and vary
in ch. # (around 100).
• Originating from hybrids between two wild
polyploid relatives, Saccharum officinarum
and Saccharum spontaneum.
• The genome is of the order of 10,000 Mbp in
size.

Scientific classification
KINGDOM Plantae
ORDER Poales
FAMILY Poaceae
TRIBE Andropogoneae
GENUS Saccharum
SPECIE S. Officinarum
BINOMIAL NAME
Saccharum officinarum
L.

ECONOMIC IMPORTANCE

• Produced in the greatest quantities globally.
More than 1,000 million tons of sugarcane are
harvested each year.
• Source of most of the sugar produced in the
world
• Efficient plant utilizing the C4 pathway of
photosynthesis (in notes) *
• Brazil is largest producer of sugarcane and
export of sugar
• China 3rd , Pak. 5th (2005)

GENETICS & CYTOGENETICS
12

• Chromosome numbers were determined,
uncovering highly polyploid and,
frequently, aneuploidy members in this
genus.
• The vast majority of S. officinarum clones
display 2n = 80 chromosomes
• Pairing behavior was studied in these
species that showed mainly bivalents

• Interspecific crosses can usually be made
among clones of the five species within the
genus Saccharum, although peculiar
chromosome numbers are observed in the
progenies of certain crosses.
• Due to abnormalities in fertilization and
embryo formation, the somatic chromosome
number is transmitted to the progeny instead
of the gametic number of the pistillate parent,
when S. officinarum is used as the maternal
parent in crosses with S. spontaneum, S.
barberi, or S. sinense.

• In the breeding of sugarcane, it has been a
general practice to cross the different species
with the noble cane, S. officinarum, to combine
the high sugar yield of the officinarum clones
with hardiness and disease resistance of the
other species, a procedure called nobilization.
• Usually, two to three backcrosses to the noble
parent are necessary to recover satisfactory
sucrose content
NOBILIZATION
15

• Simple Mendelian genetic studies are virtually
impossible in sugarcane owing to the high
polyploid number and irregular transmission
of individual chromosomes, to meiotic
irregularities arising with cross fertilization,
and to sterility problems that make crossing
and selfing difficult.
• Greater attention is given to quantitative
genetic inheritance in sugarcane than to the
inheritance of qualitative characters.
Inbreeding, where possible, leads to the rapid
loss of vigor.

• Inbreeding is restricted in particular clones
due to presence of self sterility or self
incompatibility. Quantitative inheritance
studies suggest that:
• Additive genetic variance is important for
many agronomic characters and disease
resistance.
• Non additive variance is important for cane
and sugar yield.

TECHNIQUES
18

• In the last 20 years hybridization tech. used
extensively in plants.
1. Genomic in situ hybridization (GISH)
2. Fluorescence in situ hybridization (FISH)
19

• Used to identify parental chromosomes in
interspecific hybrids.
• To test the origin of natural amphiploids, to
track down the introgression of alien
chromosomes or to test the occurrence of
exchange between the genomes involved
GENOMIC IN SITU HYBRIDIZATION (GISH)
20

• This technique can reveal the physical
location of repeated, low-copy-number or
unique DNA sequences, provide useful
cytological markers and enable comparisons
between physical and genetic maps. These
techniques proved to be particularly relevant
to refine our understanding of the genome
structure of sugarcane and its taxonomy.
FLUORESCENCE IN SITU HYBRIDIZATION (FISH)
21

To answer specific questions regarding:
• Origin of S. barberi and S. sinense
• Basic chromosome number in S. spontaneum,
S. officinarum and S. robustum
• Genome structure of modern sugarcane
cultivars
• Introgression with other genera
APPLICATION
22

• The Basic chromosome number of X= 5, 6, 7,
8, 9, 10 and 12 suggested for Saccharum spp.
• S. officinarum 2n=80, X=10
• Basic chromosome number X= 10 most
common in Andropogoneae.

WHY STRUCTURAL DIFF. EXPECTED IN
MODERN CULTIVAR?
24

• Studies have shown that the two major
species involved in modern cultivars have
different basic chromosome number; X= 10
for S. officinarum and X= 8 for S. spontaneum.

SOURCES
26

1. Basic Information on the
Sugarcane Plant 1
Robert J. Henry
2. Molecular Cytogenetics 9
Nathalie Piperidis, George Piperidis
and Angélique D’Hont
27

Genetics and cytogenetics of SACCHARUM OFFICINARUM

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