Characterization and evaluation of transgenic events of chickpea containing the DREB1A transcription factor for tolerance to drought stress under contained greenhouse and field conditions
Duration: 10/Aug/2010 - 30/Sep/2013
Project contact: Sharma, KK , Sharma, HC
Donor: Department of Biotechnology (DBT)-Government of India-India
Regulatory genes or transcription factors (TF), more specifically those belonging to the AP2/ERF family have been shown to improve plant stress tolerance by regulating the coordinated expression of several stress-related genes in heterologous transgenic plants. At ICRISAT, we have developed a large number of groundnut and chickpea transgenic plants with Arabidopsis thaliana DREB1A driven by the rd29 gene promoter of A. thaliana and found that certain transgenic events had an increased Transpiration Efficiency (TE) under both well-watered (WW) and water stress (WS) conditions. The enhanced TE in the selected transgenic plants was related to a lower stomatal conductance and an overall lower rate of water loss per unit of leaf area. Further studies have indicated a significant correlation between TE and SCMR (Spad chlorophyll measurement reading); TE and SLA (Specific leaf area), and SLA and SCMR under drought stress (DS) conditions in two sets of greenhouse experiments. However, the relationship between TE and Δ13C could not be established in this study, either for WW or DS treatments. Further, the groundnut transgenic plants were tested in a lysimetric system and upon exposure to water deficit, the root growth of DREB1A-overexpressing transgenic events enhanced dramatically when compared to the WT parent; by contrast, no rooting differences were seen under WW conditions. The differences in rooting density under WS contributed significantly to a higher water uptake. Hence, it would appear that the overexpression of At DREB1A in groundnut when driven by a stress-inducible promoter results in the modulation of various native genes involved in stress response, thereby enhancing adaptation under water limiting conditions. Based on the encouraging results obtained so far, we propose to continue our efforts on further evaluation of the performance of the selected transgenic events for various traits that contribute to drought tolerance.