Controlled Over-Expression of AtDREB1A Enhances Tolerance against Drought and Salinity in Rice

Engineering transcription factors (TF) hold promise in enhancing abiotic stress tolerance in plants. In this study, one of the popular rice varieties of South India, namely ADT 43, was engineered with a TF AtDREB1A driven by a stress-inducible rd29A promoter. PCR and Southern hybridization were employed to confirm the integration and copy number of the transgene. Transgenic lines (T1) of ADT 43 showed enhanced tolerance to drought and salinity compared to the non-transgenic ADT 43. Transgenic lines were found to maintain higher RWC %, lower leaf temperature, and partially closed stomata, enabling better survival under stress conditions. qRT-PCR analysis revealed the strong induction of AtDREB1A transcripts during drought. Transgenic lines of ADT 43 exhibited increased germination and retention of chlorophyll in their leaves under salinity. Evaluation of transgenic lines under transgenic screen house conditions revealed that line # A16 exhibited on par agronomic performance against its non-transgenic counterpart under normal conditions. Under drought, non-transgenic ADT 43 showed >20% reduction in the total number of spikelets per panicle, whereas transgenic line # A16 registered only a 2% reduction. Non-transgenic ADT 43 recorded 80% yield reduction under drought, whereas line # A16 recorded only 54% yield loss. The above results demonstrated the effectiveness of controlled expression of DREB1A in regulating dehydration responses in rice.