OsMsr9, a novel putative rice F-box containing protein,confers enhanced salt tolerance in transgenic rice and Arabidopsis

Salinity is a major environmental stress that limits agricultural production and geographical distribution of plants. In a previous study, it has been shown that OsMsr9 was induced by cold, drought and heat stresses. However, functions of OsMsr9 at physiological and molecular levels are still unknown. Here, we report that OsMsr9 plays roles in salt tolerance in plants. Quantitative real-time PCR (qPCR) analysis revealed that OsMsr9 was also rapidly and strongly induced by salt stress. Overexpression of OsMsr9 in Arabidopsis and rice showed enhanced salt stress tolerance displaying increased shoot and root elongation, higher survival rates in transgenic plants compared with wild type. OsMsr9 might act as a positive regulator of plant salt tolerance with reinforced expression of stress-related genes, such as RD29A, DREB2A and RAB18 in transgenic plants under salt conditions. Furthermore, transgenic plants accumulated more compatible solutes (proline and soluble sugar) and low level of malondialdehyde, alleviating the changes in reactive oxygen species. These results indicate that OsMsr9 could be a useful gene in developing transgenic crops with enhanced salt tolerance.