ICRISAT Archival Report 2006 - The seedlings of success in the ...

Milestone: Five promising TSVcp transgenic events identified and the disease resistance characterized under
contained field conditions (KKS/PLK/SNN) 2009
Milestone: Two best transgenic events with resistance to TSV used for introgression into locally adapted groundnut
genotypes and their evaluation (KKS/PLK/SNN/RA) 2010
Milestone: Commercialization package for groundnut with transgenic resistance to TSV available for deployment
(KKS/PLK/SNN/RA) 2011
Activity 6A.2.2: Develop transgenic events of groundnut for resistance to PBNV and evaluate their performance
under contained greenhouse and field conditions
Milestone: 100 transgenic events of groundnut with PBNVnp gene or alternative gene developed and screened in
contained greenhouse (KKS/PLK/SNN/RA) 2008
Peanut bud necrosis disease (PBND) is an economically important virus disease of groundnut caused by Peanut bud
necrosis virus (PBNV), transmitted by thrips, for which no durable resistance is available in the groundnut
germplasm. Transgenic approach was undertaken to engineer resistance to PBNV using nucleoprotein (PBNVnp)
gene in groundnut cultivar JL 24. Forty-eight independent transgenic events were produced by using two binary
vectors encoding for PBNVnp gene through Agrobacterium tumefaciens and micro-projectile mediated genetic
transformation. The progeny of the transgenic plants were mechanically inoculated with PBNV at two
concentrations, 1: 50 and 1: 100 (w/v) under P 2 greenhouse conditions. In the T 1 generation, at 1: 100 concentration
of leaf sap inoculum, 24 of the 36 events tested did not show any symptoms and virus was not detected in these
plants with ELISA. However, at higher concentration [1: 50], all the 24 events were infected by the virus, but the
symptoms were delayed by 40 to 60 days in six events, when compared with the untransformed controls, which
showed nearly 100% mortality within two weeks after inoculation. The 24 events were evaluated in a contained onstation
trial at ICRISAT, Patancheru farm, during 2005. Planting was done with wide spacing to attract thrips vector
for the virus inoculation. Most of the 24 events were affected by PBND, however, symptom appearance was delayed
by 2 to 3 weeks in the transgenic plants compared to the controls. Although all the infected transgenic groundnut
plants showed severe PBND symptoms, eight plants from the events B 8, B 9, B 11, B 13, B 15, B 19, B 20, and B
22 showed recovery, suggesting some tolerance to PBND. Apparent lack of resistance to PBNV in transgenic plants
could be attributable to the presence of RNA silencing suppressor gene, NSs, in the PBNV genome, which could be
rendering PBNVnp gene ineffective. Further studies have been planned to develop RNAi construct to counter the
effect of NSs gene for transformation either by genetic engineering or conventional crossing into PBNVnp
transgenic events. In addition, strategies are being developed to use RNAi constructs for conserved domains of
PBNV replicase, nucleoprotein or movement genes, combined with RNAi constructs to counter and NSs gene for
inducing RNAi-mediated resistance to PBNV in groundnut and other crops susceptible to this virus.
KK Sharma, Lava Kumar and Farid Waliyar
Progress reported towards the achievement of milestone for 2008 will contribute towards achievement of the
milestones listed below.
Milestone: At least 10 promising transgenic events identified and resistance to PBNV characterized under contained
greenhouse conditions (KKS/PLK/SNN/RA) 2009
Milestone: Five promising PBNVcp or alternative gene transgenic events identified and the disease resistance
characterized under contained field conditions (KKS/PLK/SNN/RA) 2010
Milestone: Two best transgenic events with resistance to PBNV used for introgression into locally adapted
groundnut genotypes and their evaluation (KKS/PLK/SNN/RA) 2011
Chickpea
Output A: Improved germplasm and varieties of sorghum, pearl millet, pigeonpea, chickpea, and groundnut
with pro-poor traits and advanced knowledge of selection tools and breeding methods made available to
partners internationally
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