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

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Output target 6B.2: High throughput molecular genetic and phenotyp<strong>in</strong>g platforms for drought and sal<strong>in</strong>ity<br />

stress and promis<strong>in</strong>g transgenic events <strong>of</strong> chickpea for tolerance to drought stress available for<br />

commercialization and <strong>in</strong>trogression <strong>in</strong> locally adapted germplasm<br />

Activity 6B.2.1: Develop and evaluate chickpea transgenic events for enhanced tolerance to drought stress<br />

Milestones: 50 transgenic events <strong>of</strong> chickpea with DREB1A and P5CSF genes developed and screened for drought<br />

tolerance <strong>in</strong> <strong>the</strong> conta<strong>in</strong>ed greenhouse (KKS/VV/PMG) 2007<br />

Genetic eng<strong>in</strong>eer<strong>in</strong>g <strong>of</strong> chickpea for enhanced tolerance to water stress is be<strong>in</strong>g carried out us<strong>in</strong>g <strong>the</strong> osmoregulatory<br />

P5CSF129A gene and DREB1A transcription factor that acts as a major “switch” that triggers a cascade <strong>of</strong> genes <strong>in</strong><br />

response to a given stress. Forty-eight chickpea events with 35S: P5CSF129A and 18 events carry<strong>in</strong>g<br />

rd29A:DREB1A were advanced to T 4 generation to ma<strong>in</strong>ta<strong>in</strong> <strong>the</strong> homozygosity. Sou<strong>the</strong>rn analysis <strong>of</strong> <strong>the</strong> tested<br />

events <strong>in</strong>dicated a low copy number (1 - 2 copies) <strong>in</strong> <strong>the</strong> 35S:P5CSF129A transgenics, whereas most <strong>of</strong> <strong>the</strong> events<br />

carry<strong>in</strong>g rd29A: DREB1A had only a s<strong>in</strong>gle copy <strong>of</strong> <strong>the</strong> transgene. Inheritance studies carried out on <strong>the</strong> T 3<br />

generation transgenic plants showed a 15: 1 segregation for both types.<br />

Ten transgenic events each <strong>of</strong> rd29A:DREB1A and 35S: P5CSF129A <strong>in</strong> T 3 generation were evaluated <strong>in</strong> drydown<br />

experiments to study various physiological parameters <strong>in</strong>clud<strong>in</strong>g plant response to soil dry<strong>in</strong>g as measured by <strong>the</strong><br />

fraction <strong>of</strong> transpirable soil water (FTSW), stomatal conductance, and transpiration efficiency (TE). <strong>The</strong> events<br />

exhibit<strong>in</strong>g a diversity <strong>of</strong> stress response patterns, especially with respect to <strong>the</strong> NTR-FTSW relationship were<br />

selected from that rank<strong>in</strong>g and comparative studies were carried out with <strong>the</strong>se transgenics under optimized<br />

conditions for evaluat<strong>in</strong>g <strong>the</strong> water use efficiency <strong>of</strong> <strong>the</strong> selected events. All <strong>the</strong> selected transgenic events differed<br />

from <strong>the</strong> wild type parent <strong>in</strong> <strong>the</strong>ir NTR response to FTSW, show<strong>in</strong>g a decl<strong>in</strong>e <strong>in</strong> transpiration at lower FTSW values<br />

(dryer soil). Several events had superior transpiration efficiency, photosyn<strong>the</strong>tic activity, stomatal conductance, and<br />

total transpiration under water limited conditions <strong>in</strong> comparison to <strong>the</strong> control parent C 235. All <strong>the</strong> selected<br />

transgenic events had a transpiration decl<strong>in</strong>e <strong>in</strong> drier soil than <strong>in</strong> <strong>the</strong> untransformed parent. <strong>The</strong> total biomass<br />

produced dur<strong>in</strong>g <strong>the</strong> dry down cycle (Δ biomass) showed differences amongst <strong>the</strong> transgenic events, thus <strong>in</strong>dicat<strong>in</strong>g<br />

apparent differences <strong>in</strong> <strong>the</strong> biomass produced per unit <strong>of</strong> water used.<br />

A repeat experiment was performed with 5 transgenic events <strong>of</strong> DREB1A and 4 events <strong>of</strong> P5CSF. We measured <strong>the</strong><br />

response <strong>of</strong> transpiration to progressive dry<strong>in</strong>g and also measured TE us<strong>in</strong>g standard protocol. Among <strong>the</strong> different<br />

events tested, one DREB1A event (RD 2) had higher TE than wild type C 235 under water deficit. This event was<br />

also among <strong>the</strong> few hav<strong>in</strong>g higher TE than control variety C 235 <strong>in</strong> <strong>the</strong> previous experiment, which confirms its<br />

superiority. One event <strong>of</strong> P5CSF (P8) also showed superior TE than control C 235, whereas TE <strong>in</strong> <strong>the</strong> o<strong>the</strong>r 3 events<br />

was similar or below C 235.<br />

V<strong>in</strong>cent Vadez and KK Sharma<br />

Progress reported towards <strong>the</strong> achievement <strong>of</strong> milestone for 2007 will contribute towards achievement <strong>of</strong> <strong>the</strong><br />

milestones listed below.<br />

Milestone: At least 8 promis<strong>in</strong>g transgenic events <strong>of</strong> chickpea conta<strong>in</strong><strong>in</strong>g DREB1A or P5CSF genes identified and<br />

<strong>the</strong>ir drought tolerance characterized under conta<strong>in</strong>ed greenhouse conditions (KKS/VV/PMG) 2008<br />

Milestone: Three promis<strong>in</strong>g transgenic events <strong>of</strong> chickpea identified for drought tolerance and characterized under<br />

conta<strong>in</strong>ed field conditions (KKS/VV/PMG) 2009<br />

Milestone: One or two transgenic events <strong>of</strong> chickpea used for <strong>in</strong>trogression <strong>in</strong>to locally adapted genotypes with<br />

better adaptation and <strong>the</strong> progeny characterized and evaluated (KKS/VV/PMG) 2010<br />

Milestone: 10 - 15 <strong>in</strong>trogressed transgenic l<strong>in</strong>es <strong>of</strong> chickpea with improved tolerance to water-limit<strong>in</strong>g conditions<br />

evaluated and development <strong>of</strong> commercialization package <strong>in</strong>itiated (KKS/VV/PMG) 2011<br />

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