The Primary Physiological Functional Analysis And Subcellular Localization Of OsRab5a In Rice (Oryza Sativa L.)

OsRab5a encodes a Rab5a protein, which belongs to the Rab family of small GTP-binding protein superfamily. OsRab5a protein plays important regulatory functions in rice (Oryza sativa L.) via the switch between active GTP-binding and inactive GDP-binding conformation. Transgenic plants with POsrab5a:: β-glucuronidase -(GUS) gene indicate that OsRab5a is expressed in root ,stem, leaf, flower and root base. Overexpressing and site-directed mutagenesis of OsRab5a showed no visible morphological and physiological changes under different environments. But after interfering with OsRab5a in callus of rice, the callus was lethal during differentiation. We also observed the expression of OsRab5a was induced by cytokinin. Furthermore the expression of OsRab5a is higher in the differentiation media than that in selection media. So we suggested that OsRab5a was possible involved in the cytokinin signal transduction pathway. To examine subcellular localization of OsRab5a, we transformed the vectors harboring GFP:: OsRab5a, GFP ::OsRab5aCA and GFP:: OsRab5aDN fused gene into Arabidopsis. Using the transgenic lines and FM4-64 (the lipophilic styryl dye), we demonstrated that OsRab5a is involved in vesicular transport and was localized on the plasma membrane and early endosomes. We also detected the site-directed mutagenesis CA and DN and found that OsRab5a is localized in the cell membrane in CA mutants and fluorescence protein(GFP) couldn't be detected in DN mutants, possible due to the distribution of OsRab5a in cytoplasm.