TRANSFORMATION STUDIES IN CHICKPEA {Dicerarietinuml.)
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Date
2007-08-30
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University of Agricultural Sciences GKVK, Banglore
Abstract
An investigation was carried out to develop transgenic chickpea for pod borer
resistance through in vitro Agrobacterium-mQ6\aXe,6. transformation compatible with in
vitro regeneration protocol and non-tissue culture based methods. Three popular cultivars
viz., A-1, ICCV-2 and GBS-963 were employed for standardization of multiple shoot
regeneration using two types of explants and different levels of TDZ and cytokinin
combinations. GBS-963 was found superior over the other two cultivars with the highest
number of shoots (31.25) across the treatments with axillary meristem as the explant. The
regeneration response was not only dependent upon genotype and explant type but also on
the growth regulator. For the root induction, liquid MS medium was found better than
solid medium. Pronounced effect of half MS over full MS for percent rooting and roots
per shoot was noted. Among various treatments, NAA exhibited high stimulatory effect
with half MS. Between two groups, kabuli cultivar yielded the highest rooting response
(72.7%) compared to desi cultivars A-1 and GBS-963 (59.5% and 58%). The development
of lateral roots and better growth of the plantlets was obtained on 1/4"^ Amon's medium.
Among the various potting media used, vermiculite was found better.
The rate of in vitro transformation was influenced by many factors such as
infection period, co-cultivation time and genetic background of the explant. In the present
study, 20 min of infection period and three days of co-cultivation resulted in high
transformation frequency. The number of transgenics produced in cultivar ICCV-2 (8.3%)
was comparably higher than in A-1 (7.4%).
Different non-tissue culture based methods were tried among which seed
imbibition resulted in highest transformation frequency (29.3%) in A-1 while shoot tip
infection in case of ICCV-2 (72.2%). Putative transgenics were screened through simple
test 'kanamycin leaf paint assay' and later confirmed by PCR using primers for nptll and
crylAc and expression analysis using Bt dip stick method. Insect bioassay confirmed the
expression of integrated crylAc gene. The mortality ranged from 0 to 60 per cent.
Thus, for the first time genetic transformation is achieved in recalcitrant species
like chickpea through non-tissue culture based methods, which are very simple, efficient
and able to generate large number of independent transgenics.
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