Characterization Of Rice And Tomato Genes Encoding S-nitrosoglutathione Reductase And Analysis Of Their Biochemical Function

S-nitrosation of proteins, one of most important post-translational modifications, plays an important role in plant responses to diverse environmental stresses. To study the function of S-nitrosation in plant disease resistance responses, we cloned and identified S-nitrosoglutathione reductase (GSNOR) genes from rice and tomato. The rice GSNOR gene, OsGSNOR1, encodes a protein of 381 amino acids, which predicts to calculated molecular weight of 40.8 kDa with isoelectric point of 7.03, while the tomato GSNOR gene, LeGSNOR1, encodes a protein of 379 amino acids, which predicts to calculated molecular weight of 40.7 kDa with isoelectric point of 6.58. Similarty searches against database revealed that both OsGSNOR1 and LeGSNOR1 contain conserved ADH_N and ADH_Zn_N domains, characteristic structures of Alcohol dehydrogenases. To identify the biochemical activity of OsGSNOR1 and LeGSNOR1, the coding regions of the two genes were cloned into a yeast expression vector and the complementation ability of OsGSNOR1 and LeGSNOR1 to the defect phenotype in yeast mutant sfa1, in which the GSNOR gene was knockout, were analyzed. The results show that sfa1 strain transformed with OsGSNOR1 or LeGSNOR1 restored the non-hypersusceptibility to GSNO, similar to that of the wild type strain; however, transformant with the vector control remains hypersensitivity to GSNO. These results demonstrated that the cloned OsGSNOR1 and LeGSNOR1 gene encode S-nitrosoglutathione reductase. To further explore the biological function of S-nitrosation in plant disease resistance responses, the OsGSNOR1 and LeGSNOR1 genes were cloned into a plant transformation binary vector and introduced into Arabidopsis thaliana. Transgenic Arabidopsis plants overexpressing OsGSNOR1 and LeGSNOR1 gene were obtained and work with these transgenic plants is in progress.