水稻分支酶基因Sbe1和Sbe3 cDNA的克隆及全序列分析

cDNA Cloning and Sequence Analysis of Rice Sbe1 and Sbe3 Genes

通过改良的 RT- PCR法合成了水稻未成熟种子胚乳 c DNA库 ,并以此为模板 ,用 PCR技术从粳稻品种武运粳 7号中克隆了分别编码淀粉分支酶 SBE 和 SBE 的 2个基因 Sbe1和 Sbe3。序列分析表明 ,克隆 Sbe1和 Sbe3基因的大小分别为 2 4 90 bp和 2 4 81bp,包含了基因完整的编码序列。 Sbe3基因与已发表基因全序列完全相同 ,同源性达 10 0 % ;Sbe1基因与已发表基因序列有 4个碱基不同 ,同源性为 99.84 % ,推导氨基酸序列的差异为

The starch branching enzyme (SBE) is a key enzyme in amylopectin biosynthesis and there are two major isoforms in rice, named SBEⅠ and SBEⅢ, which are encoded by the Sbe1 and Sbe3 genes, respectively. These two genes were cloned from the template cDNA library, which was synthesized by improved RT PCR technique from the mRNAs of the immature rice seeds of japonica rice Wuyunjing 7. DNA sequencing analysis showed that the size of the cloned Sbe1 and Sbe3 cDNAs were 2490 bp and 2481 bp, respectively, and carried their entire coding sequences. Comparison analysis indicated that the Sbe3 sequence was the same as the reported and their homology was 100%. There were only four base pairs difference, which resulted in two deduced amino acids alteration, between the cloned Sbe1 cDNA and the reported.