[Objective] The aim was to construct promoter of maize starch-branching enzyme sbe Ⅱb gene specifically expressed in seed.[Method] The promoter sequence of maize starch-branching enzyme sbe Ⅱb gene was amplified by LA-PCR and then cloned into pMD18-T vector.Subsequently,the promoter was cloned into pBI121 vector to construct plant expression vector pBI121-sbe Ⅱb.Recombinant plasmid pSBE-GUS was constructed by connecting GUS gene into pBI121-sbe Ⅱb and transformed into tobacco mediated by Agrobacterium tumefaciens,before detection by PCR and Southern blot.The biochemical analysis and fluorescence detection of GUS activity were performed in different parts of the tobacco by Gene Gun Method and Agrobacterium tumefaciens transformation respectively.[Result] The homology between promoter sequence cloned in this experiment and the corresponding sequence announced in the GenBank reached 98.52%.Four transformed tobaccos were obtained by PCR and Southern blot after co-culture and selective culture.A small number of blue spots appeared in leaves,and the spots could barely been seen in the stems and roots,while a large number of blue spots were found in seeds.So,it could be concluded that the promoter of sbeⅡb gene was specifically expressed in seeds.[Conclusion] Promoter of maize starch branching enzyme sbe Ⅱb specifically expressed in seeds was successfully cloned.
