小麦籽粒淀粉分支酶同工酶基因型与酶活性关系研究

Relationship between Isozyme Genotypes and Activities of Starch Branching Enzyme in Wheat Grain

测定了71个小麦品种的籽粒淀粉分支酶活性,并采用非变性聚丙烯酰胺凝胶电泳(Native-PAGE),鉴定了分支酶同工酶的基因型,以明确小麦籽粒淀粉分支酶(SBE)各同工型等位基因的分布特点和基因型组成,阐明分支酶活性与分支酶同工酶基因型的相关性。结果表明,分支酶有SBEⅠ和SBEⅡ两个基因位点,SBEⅡ位点未显现多态性,SBEⅠ位点存在多样性。在SBEⅠ位点鉴定出A、B、Di和Dii共4个等位基因位点,各等位基因位点出现频率分别为9.9%、76.1%、95.8%和57.8%;共检测到9种基因型,其中基因型DiDiiB、DiB和DiDii有较高的分布频率,分别为45.1%、28.2%和8.5%。从单一位点分析,分支酶活性与SBEⅠ位点有显著的相关性,与SBEⅡ位点相关性不显著。由此可见,小麦籽粒胚乳淀粉分支酶同工酶不同基因位点和基因型对酶活性具有不同的遗传效应。

To elucidate distribution of alleles, genotype composition and correlation between isozyme genotypes and enzyme activities of starch branching enzyme （SBE） in wheat （ Triticum aestivum L. ） grains, total activity of SBE was measured in seventy-one wheat cuhivars with different provenances, including some typical hexaploid wheat from various province of China and some high-yielding modern varieties as well as eight exotic ones. The allele loci and genotypes of SBE isozymes were also investigated using native polyaerylamide gel electrophoresis （Native-PAGE）. The results showed that there were two loci of starch branching enzyme, SBE Ⅰ and SBE Ⅱ . SBE Ⅱ failed to exhibit genetic polymorphism but SBE Ⅰ manifested genetic diversity. Four alleles were identified at SBE Ⅰ locus, that was A, B, Di , and Dii, with frequency 9.9 %, 76.1%, 95.8 %, and 57.8 %, respectively. Nine genotypes were determined, of them genotype Di Dii B, Di B, and Di Dii took on high frequency with 45.1% , 28.2% , and 8.5 % , respectively. From single locus analysis, starch branching enzyme activity correlated to SBE Ⅰ locus, but no significant correlation to SBE Ⅱ was observed. Therefore it indicated that different gene loci and genotypes of starch branching enzyme in wheat had different genetic impacts on enzyme activities.