Jacalin domain-containing protein OsSalT interacts with OsDREB2A and OsNAC1 to impart drought stress tolerance in planta

With the changing climatic conditions, drought has become one of the most threatening abiotic stress factors that adversely affect rice cultivation and productivity. Although the involvement of the jacalin domain-containing protein, Os SalT, has been reported in drought and salinity tolerance, its functional mechanism still remains largely unexplored. In this study, expression of the OsSalT gene was found to be positively correlated with the drought tolerance potential with its higher transcript abundance in the tolerant indica rice cultivar, Vandana and lower abundance in the susceptible cultivar, MTU1010. Moreover, the ectopic expression of Os SalT in tobacco imparted drought stress tolerance in the transgenic lines. The transgenic lines exhibited significantly improved growth and higher osmolyte accumulation over the wild-type (WT) plants together with the induction in the Os SalT expression under drought stress. Fascinatingly, the yeast two-hybrid and bimolecular fluorescence complementation (BiFC) analyses confirmed the interaction of Os SalT protein with two interesting transcription factors (TFs), Os NAC1 and OsDREB2A. In silico analysis further revealed that the Os SalT protein interacted with the regulatory domain of Os DREB2A and the C-terminal domain of Os NAC1 leading to their activation and induction of their downstream drought-responsive genes. Together, this study unravels a novel model for Os SalT-mediated regulation of drought tolerance in plants.