Overexpression of <i>TaSnRK2.9s</i> Improves Plant Growth and Development in Rice (<i>Oryza sativa</i> L.)

ABSTRACT Sucrose nonfermenting‐1 related protein kinase (SnRK2) is an important family of stress signalling genes related to nutrient utilisation, metabolic regulations and responsive to external stressors. In this work, all three copies of TaSnRK2.9 were extracted from wheat ( Triticum aestivum L.) chromosomes 5A, 5B and 5D. To elucidate the function of TaSnRK2.9s , copies were cloned, and functional characterisation was performed under normal and abiotic stress conditions. Agrobacterium‐mediated technique was used to transform wild‐type (WT) Kittakee rice. The transgenic (T3) rice lines phenotyped for the targeted traits and compared with WT rice. Relative gene expression analyses revealed that TaSnRK2.9s mainly expressed in root tissues and was responsive to PEG‐6000, NaCl and low temperature suggesting the involvement of SnRK2s in signal transduction pathways dependent on ABA. Overexpression of TaSnRK2.9s resulted in enhanced root development, grains per spike and spike length in the transformed rice. Higher cell membrane stability values and decreased chlorophyl a/b ratios under drought conditions clearly highlight the role of the TaSnRK2.9s in improvement of growth and development. Hence, TaSnRK2.9s is a multifunction regulator and can be instrumental in wheat and transgenic breeding in rice against drought.