cDNA Cloning and Sequence Analysis of Rice Sbe1 and Sbe3 Genes

摘要

Two starch-branching enzyme (SBE) in rice, is known to be a key enzyme in amylopectin biosynthesis. The cDNA of two SBE(starch-branching enzyme) genes Sbe1 and Sbe3 encoding SBE Ⅰ and SBE Ⅲ (two major isoforms in rice) were cloned by an improved RT-PCR technique, from a template cDNA library derived from the total mRNAs extracted from the immature seeds of a japonica rice Wuyunjing 7. DNA sequence analysis showed that the size of the cloned Sbe1 and Sbe3 cDNAs were 2490 and 2481 bp long, respectively, including their entire coding sequences. Comparison analysis indicated that the nucleotide sequence of Sbe3 was the same as that of sbe3 (Genbank Accession No. D16201) as reported previously. There were only four base-pairs difference, which resulted in changes of two deduced amino acids between the cloned Sbe1 cDNA and the reported sbe1 (Genbank Accession No. D11082). The cloned Sbe1 and Sbe3 cDNAs make it possible to improve rice starch quality through genetic engineering.