小偃麦异附加系TAI-13中来自中间偃麦草的低分子量麦谷蛋白亚基基因的分子克隆

摘要

The glutenin composition and low-molecular-weight glutenin subunit (LMW-GS) genes of Triticum aestivurm L.-Agropyron intermedium (Host) Beav alien addition set Ⅰ (TAI-11-TAI-16) were analyzed by SDS-PAGE and genomic PCR, respectively. The results indicated that the addition line TAI-13 carries both high-molecular-weight glutenin subunit (HMW-GS) and LMW-GS gene loci and that the extra Ag. intermedium chromosome pair in TAI-13 belongs to homoeologous group 1. Four LMW-GS genes located on the added Ag. intermedium chromosome in TAI-13 line have been isolated from immature endosperm of TAI-13 by RT-PCR approach. Sequence analysis showed that three of them (13003, 13006and 13054) contained complete ORFs of genes, the other one, 13514 was a partial gene lacking of coding sequence of signal peptide. According to the N-terminal amino acid sequences deduced from nucleotides,the four LMW glutenin subunits could be classified into three types, i.e. Ai-M type (LAilencoded by 13514),Ai-Q type (LAi2 and LAi3 encoded by 13006 and 13045, respectively) and Ai-I type (LAi4 encoded by 13003).Ai-M and Ai-Q are novel LMW-GS types compared with the known LMW-GSs of wheat. The analysis of deduced amino acid sequence showed that the LAi1 had the specific primary structure, nine Cys residues and longer repetitive region. These characters of LAi1 may have positive effect on strength and viscoelasticity of wheat flour.%通过分析小麦(Triticum aestivum L.)-中间偃麦草(Agropyron intermedium(Host)Beav)异附加系TA1-Ⅰ系列的麦谷蛋白SDS-PAGE电泳图谱和基因组DNA的PCR扩增产物,发现在异附加系TAI-13中附加的中间偃麦草染色体上具有编码高分子量和低分子量麦谷蛋白亚基基因的位点,属于第一同源群.随后,采用RT-PCR方法,从TAI-13的未成熟子粒中克隆了4个来自中间偃麦草的低分子量麦谷蛋白亚基基因.序列分析表明,13003、13006和13054是包括信号肽编码序列的全长基因,而13514没有信号肽编码序列.根据由核苷酸序列推导的蛋白质分子的N-末端氨基酸序列,这4个基因编码的麦谷蛋白亚基可分为3种类型,即Ai-M型(由基因13514编码,命名为LAi1)、Ai-Q型(由基因13006和13045编码,分别命名为LAi2和LAi3)和Ai-Ⅰ型(由基因13003编码,命名为LAi4).通过与小麦的低分子量麦谷蛋白亚基分子比较,发现Ai-M和Ai-Q是两种未见报道的新的低分子量麦谷蛋白亚基类型,而Ai-Ⅰ型与小麦的Ⅰ型亚基相似.氨基酸序列分析发现,基因13514编码的蛋白质亚基分子LAi1有较长的重复区(26个重复模块)和较多的半胱氨酸残基(9个),推测其可形成3个分子间二硫键,可能对增强面团的强度和粘弹性有正面效应.