Overexpression of a stress response membrane protein gene OsSMP1 enhances rice tolerance to salt, cold and heavy metal stress

Salt, cold and heavy metals are major factors limiting crop productivity and quality. Here we report the role of OsSMP1 (stress membrane protein) of rice in response to abiotic stress. Gene chip analysis showed the expression level OsSMP1 was significantly increased in rice under cold, drought and heat treatment. The results of RT-PCR showed that the relative expression level of the OsSMP1 gene was up-regulated in rice under ABA, high salt and cold treatments. There were some cis-elements upstream of OsSMP1 that regulate ABA, low temperature and drought. The result of OsSMP1pro: GUS transgenic plant is consistent with that of the gene chip and RT-PCR. OsSMP1-GFP fusion protein expression showed that OsSMP1 was mainly localized on the cell membrane. Overexpression of OsSMP1 improves rice tolerance to salt, cold and heavy metal (CdCl2 and CuSO4) stress but increases rice sensitivity to abscisic acid. These results imply that OsSMP1 is a positive regulator of rice tolerance to salt, cold and heavy metal via an ABA-dependent pathway and is potential for improving rice tolerance to abiotic stress.