A DUF966 gene family member OsDSR3 positively regulates alkali stress tolerance in rice

Rice growth and production are severely constrained by alkali stress. However, the mechanism underlying the rice tolerance to alkali stress is unclear. OsDSR3, a novel gene from the domains of unknown function 966 (DUF966) family, was identified and characterized for its function in the response of rice to alkali stress. The result of this study clearly showed that alkali stress significantly induced OsDSR3 expression level. Moreover, the expression of OsDSR3 was up-regulated by drought, salt, cold, H2O2 and abscisic acid (ABA), and down-regulated by gibberellic acid (GA3), and 2,4-Dichlorophenoxyacetic acid (2,4-D) treatments. Subcellular localization exhibited that OsDSR3 was detected in the nucleus and membrane. OsDSR3-overexpressing (OsDSR3-OE) plants showed higher tolerance to alkali stress than the wild-type (WT). In contrast, OsDSR3 knockout (OsDSR3-KO) mutants were more vulnerable to alkali stress. The differentially expressed genes (DEGs) among OsDSR3-OE and WT seedlings were mainly enriched in porphyrin and chlorophyll, starch and sucrose, and carotenoid metabolic pathways. Among these DEGs, 26 were identified as potential alkali stress-responsive genes, including several up-regulated genes like OsHAK5, OsGRX23 and OsNIR2. Consistent with the expression profiles of metabolic pathways-related genes, most of the metabolite contents and metabolite synthases activities were improved in OsDSR3-OE lines and decreased in OsDSR3-KO lines compared to WT. This may explain the higher tolerance of OE lines and lower tolerance of KO lines to alkali stress. These findings suggested that OsDSR3 positively regulates rice tolerance to alkali stress, which will help to elucidate the molecular mechanism underlying rice alkali tolerance.