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Bioscience Methods 2012, Vol.3, No.2, 7
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9
to detect genetic stability of
in vitro
regenerated
plants by Williams et al (1990). These benefits justify
the frequent application of the technique in genetic
variability studies by Mondal and Chand (2002);
Bennici et al (2003) and Feuser et al (2003).
Biotic stresses such as insect, pests and diseases are
the alarming threats for sugarcane grass. Whip smut,
Shoot borer, giant borer, Red rot, Leaf scald, Eye spot,
Mosaic virus, Pineapple disease, Ratoon stunting
disease are the major threats for sugarcane. Whip smut
is a serious threat for sugarcane and occurs in almost
all sugarcane growing countries Comstock (2000).
Few attempts have been made to develop resistance
against the most devastating disease. These are
pre-plant heat therapy of planting sets of sugarcane;
pre-plant fungicidal dips of planting sets and
screening of sugarcane clones for identification of
resistant varieties against the pathogen. Genetic
mapping with SSR marker was done for sugarcane
smut resistance by Raboin et al (2001). A recent report
describes the use of cDNA-AFLP and suppression
subtractive hybridization (SSH) to identify differentially
expressed sugarcane genes upon inoculation with the
sugarcane smut fungus
U. scitaminea
. Using a
Restriction Fragment length Polymorphism (RFLP)
approach, markers were developed and used on a
population of 78 well characterized sugarcane genotypes
that are used in a breeding program. In this study, 59
polymorphisms showing correlation with smut
resistance were identified. PCR and microscopy
were used for smut disease assessment in sugarcane
(Singh et al., 2004). Amplified Fragment length
Polymorphism (AFLP) analysis of cDNA was used to
identify sugarcane genes differentially expressed in
disease-resistant but not in susceptible sugarcane
somaclones (Hidalgo et al., 2005).
Several strategies have been used to improve plant
defense against insects and pathogens. The activation
of stress-response transcription factors was found to
enhance plant tolerance to fungal and bacterial
pathogens in transgenic plants by Gu et al (2002).
However, little is known about the function of
other components of the plant transcription machinery
during stress. The identification and characterization
of agronomically interesting genes related to herbivores
and pathogens are a major challenge for sugarcane
functional genomics. One of the most promising areas
is to improve insect control through the use of
proteinase inhibitor genes Allsopp et al (1997) and
Nutt et al (1999) or Bt genes Arencibia et al (1997)
against the sugarcane borer (
Diatraea saccharalis
),
responsible for considerable losses in the field. For
over ten years now, the directed genetic modification
of sugarcane has been a reality in laboratories and
field trials has been conducted (Bower and Birch,
1992; Gallo-Meagher and Irvine, 1996; Leibbrandt
and Snyman, 2003; Manickavasagam et al., 2004).
Genes can be silenced or over expressed to study their
function and to produce new phenotypes not possible
through conventional breeding. But genetic manipulation
through biotechnology such as marker assisted tool
(Butterfield, 2005), DNA mapping (Grivet et al., 1996)
and genetic transformation have emerged as novel
approaches. Successful genetic transformation of
cry1Ab gene for shoot borer (
Chilo infuscatellus
)
(Arvinth et al., 2010),
Chitinase
and
Chitosanase
genes against
Colletotrichum falcatum
which cause
Red rot disease in sugarcane crop (Ijaz, 2012).
1 Results
1.1 Sugarcane
in vitro
studies
Disease free planting material is a necessary component
for propagation of next generation for getting higher
yield. Tissue culture is an ideal technique for the
production of problem free plants in a short time from
small amount of planting material.
In vitro
culture of
sugarcane provides the planting material throughout
the year for the formation of stable transformant lines.
Callus formation followed by regeneration varies
among genotypes which depicts that genotype plays a
significant role in callus formation and regeneration.
Therefore, it is significant for every genotype to
optimize media with different levels of plant growth
regulators along with growing conditions so that
optimum regeneration could be attained. Yield is a
major constraint to make it a green profitable crop
which mainly attributed to insect pest and diseases.
Whip smut is a major hurdle for getting good yield.
Therefore, under these circumstances this study was