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 withPOsrab5a::β-glucuronidase (GUS) gene indicatethat OsRab5a is expressed in callus, root, stem,leaf, root base and spikelet (Figs.1, 2H–I). Usingthe transgenic Arabidopsis with fused gene ofGFP::OsRab5a and GFP::OsRab5aCA and byusing FM4-64 (the lipophilic styryl dye) staining,we have demonstrated that OsRab5a is involvedin vesicular transport and GFP-OsRab5a is local-ized on the plasma membrane and early endosomes(Fig.2A–C), while GFP-OsRab5aCA is localizedin the cell membrane (Fig.2D–F). The reductionof expression of OsRab5a in callus RNAinterference, however, led to the lethality of callusduring differentiation (Fig.3D–F). The expressionof OsRab5a was upregulated slightly by exogenouscytokinin (Fig.4), and was higher in the differen-tiation medium than that in selection medium (Fig.3G–I). These results suggest that OsRab5a playsan important role in callus differentiation probablythrough mediating hormone signal transduction.