高温胁迫下水稻胚乳淀粉分支酶各同工型基因的表达特征

 以稻米品质温度敏感型的早籼稻品种浙辐49为材料，利用人工气候箱控温处理试验和实时荧光定量PCR技术，探讨了水稻发育胚乳中淀粉分支酶(starch branching enzyme, SBE)的3种主要同工型基因 (SBEⅠ、 SBEⅢ和SBEⅣ) 在不同温度处理下的相对表达量差异及动态变化特征。结果表明，高温处理对水稻胚乳中SBE基因的表达调控因其同工型的种类而异，SBEⅣ基因在高温处理下呈上调表达，而SBEⅠ和SBEⅢ基因在高温处理下的相对表达量则明显降低，表现为下调表达；与SBEⅣ等同工型相比，水稻胚乳中SBEⅠ基因对高温胁迫的表达响应相对更敏感。

Differential Response of Three Isoform Genes Encoding Starch Branching Enzymes (SBE) in Rice Endosperms to High Temperature Stress at the Filling Stage

An early indica rice variety (Zhefu 49), whose grain quality and starch structure are sensitive to environmental temperature, was subjected to different temperature treatments (32℃ for high temperature and 22℃ for optimum temperature) at the filling stage in plant growth chambers, and the differential expressions of three isoform genes encoding the starch branching enzyme(SBE) in developing endosperms, including SBEⅠ， SBEⅢ and SBEⅣ， were detected by using real time fluorescence quantitative PCR (FQ PCR). The effects of high temperature on the expression of SBE genes in rice endosperms were isoform dependent, with relatively low expressions (down regulation) for SBEⅠ and SBEⅢ， but relatively high expression(up regulation) for SBEⅣ when rice plants were exposed to high temperature. Compared to SBEⅣ and SBEⅢ genes, the expression of SBEⅠ gene in developing rice endosperms was more sensitive to high temperature at the filling stage.