[A preliminary analysis of the function of the OsRab5a gene in rice (Oryza sativa L.)]

OsRab5a encodes a Rab5 protein in rice, which belongs to the Rab family of small GTP-binding protein superfamily. Transgenic plants with POsrab5a::beta-glucuronidase (GUS) gene indicate that OsRab5a is expressed in callus, root, stem, leaf, root base and spikelet (Figs.1, 2H-1). Using the transgenic Arabidopsis with fused gene of GFP::OsRab5a and GFP::OsRab5aCA and by using FM4-64 (the lipophilic styryl dye) staining, we have demonstrated that OsRab5a is involved in vesicular transport and GFP-OsRab5a is localized on the plasma membrane and early endosomes (Fig.2A-C), while GFP-OsRab5aCA is localized in the cell membrane (Fig.2D-F). The reduction of expression of OsRab5a in callus RNA interference, however, led to the lethality of callus during differentiation (Fig.3D-F). The expression of OsRab5a was upregulated slightly by exogenous cytokinin (Fig.4), and was higher in the differentiation medium than that in selection medium (Fig.3G-I). These results suggest that OsRab5a plays an important role in callus differentiation probably through mediating hormone signal transduction.