Functional validation of a water deficit stress responsive AP2/ERF family transcription factor-encoding gene in Oryza sativa

Cloning of drought responsive genes and validating their function are essential to crop improvement. In the present study, a drought responsive AP2/ERF family transcription factor was isolated from drought-tolerant Oryza sativa L. cv N-22 (AP2/ERF-'N-22'). Embryogenic calli produced in vitro from dehusked mature seeds of rice were bombarded with a gene construct containing AP2/ERF-N22, driven under inducible promoter RD29A from Arabidopsis using the Biolistic method. The bombarded calli were selected on hygromycin-containing selection medium. Molecular analysis of regenerated plants confirmed the integration and enhanced expression of the gene under water deficit stress (WDS). Transgenics showed 1.4 fold more expression as compared to wild-type (WT) under control condition and up to 2 fold more expression of AP2/ERF-'N-22' under water deficit stress as compared to WT. Molecular analysis of regenerated plants confirmed the integration and enhanced expression of the gene under water deficit stress. The transformation efficiency was found to be nil, 0.97% and 3.11% for overstored seeds >= a year, >= a year and fresh seeds respectively. Transgenics showed 1.4 fold more expression under control condition and up to 2 fold more expression under WDS as compared to wild-type (WT). About 90% of the plants reached maturity and showed no negative phenotypic effects or aberrations as observed earlier under a constitutive promoter from that of the WT. Physiobiochemical analysis of transgenics showed enhanced drought tolerance.