不同小麦品种及其近缘种LMW-GS基因的克隆、比较与功能标记研发

High molecular weight and low molecular weight glutenin subunits (HMW- and LMW-GS) are the main factors for the quality improvement and the genetic studies of wheat. LMW-GS accounted for about one third of seed storage proteins and 60% of gluten fraction in wheat, and were difficult to be discriminated by direct analyzing them due to the larger number of expressed subunits and their overlapping mobility with the abundant gliadin proteins in SDS-PAGE. Therefore, the characteristics of LMW-GS and their coding genes are less known, compared with HMW-GS, and are needed to be studied carefully and urgently. In the present study, based on the LMW-GS genes cloned by ourself before and registered in Genbank and our technical reserve, the gene-specific primers would be designed and used to amplify 9 wheat varieties with differnet gluten and their relatives such as Triticum monococcum, Triticum speltoides，Aegilops tauschii, Triticum dicoccum, Triticum durum, etc. The gene composition and characteristics, the difference of base and amino acid between haplotypes at Glu-3 loci, and their relationship with LMW-GS mobolity alleles and quality would be studied and analyzed thoroughly. We also plan to find and clone some new LMW-GS genes related to good quality, from which a set of function markers would be developed. Then the technology system of quality improvement by molecular marker assisted selection and pyramiding breeding would be established. These markers would be used and validated in wheat breeding practice. The result would lay a solid foundation for wheat quality improvement using conventional breeding and transformation technology.

高低分子量麦谷蛋白亚基是小麦品质改良和遗传研究的重要内容。低分子量麦谷蛋白亚基约占麦谷蛋白的60%，编码基因拷贝数多，分子量与醇溶蛋白相近，电泳难以区分，不及高分子量麦谷蛋白亚基研究清楚，是目前品质育种亟待解决的难题。本研究在先前克隆的一系列低分子量麦谷蛋白亚基基因的基础上，依靠自身的技术储备和Genbank的基因信息设计特异引物，利用掌握的PCR、克隆等技术，对具有不同筋力类型的小麦品种及其近缘种一粒小麦、拟斯卑尔脱小麦、节节麦、二粒小麦等的LMW-GS基因进行扩增、克隆、比较和分析。深入研究小麦及其近缘种Glu-3位点的基因构成、特征、单元型之间的碱基和氨基酸差异及其与品质的关系，试图鉴定并克隆出一些与品质密切相关的新LMW-GS基因，开发出相应的功能标记，建立一套以品质改良为目标的分子标记辅助选择和聚合育种技术体系，并在小麦育种实践中加以利用、验证、修订和完善。

低分子量麦谷蛋白约占小麦种子贮藏蛋白的三分之一，对面团延展性和食品加工品质有重要影响。本研究利用小麦Glu-3基因的特异引物对10份强筋型、中筋型和弱筋型小麦品种及9份小麦近缘种（野生二粒小麦、栽培二粒小麦、硬粒小麦及野生一粒小麦） 的LMW-GS基因进行了扩增和鉴定。在小麦材料中共发现14个新的基因变异类型和4个肽链变异类型，包括4个Glu-A3单元型、1个Glu-B3单元型和9个Glu-D3单元型。在小麦近缘种中共发现15个新的Glu-A3基因变异类型，包括5个GluA3-1、5个GluA3-2和5个GluA3-3单元型。同时，还发现2个编码9个半胱氨酸残基的Glu-A3基因型和1个编码7个半胱氨酸残基的Glu-D3基因型，三者可能属于优良品质亚基。前者是来自小麦品种师栾02-1和栽培二粒小麦DM2的GluA3-18单元型以及来自野生一粒小麦B03的GluA3-312单元型；后者是来自小麦品种偃展4110的GluD3-13单元型。在此基础上研发出5个Glu-A3基因特异标记。研究结果为完善了小麦低分子量谷蛋白亚基的基因构成以及以品质改良为目标的分子标记辅助选择提供了理论基础。