解析小麦淀粉品质的遗传控制及其互作网络

Wheat is one of the most important food crop, and its starch primarily determine the quality of Chinese traditional food. Starch quality was mainly determined by starch synthesis pathway. Based on characterization of starch synthesis genes in Chinese spring and the whole-genome association analysis of starch quality in common wheat, we plan to perform the field experiments for two years at two locations for 300 wheat germplasm, including landraces, varieties with high yield potential or dough quality released in last fifty years. The starch quality parameters will be determined, including amylose and amylopectin content and ratio, gelatinization characteristics and starch particle size, which will reveal the evolution and distribution of starch quality of Chinese wheat varieties. Meanwhile, the genes coding for the starch synthesis key enzymes will be sequenced using the third generation of single molecule DNA sequencing platform (PacBio RS II) to obtain the gene composition and allelic variation in these wheat germplasm. With the starch quality and the gene composition and allelic variation, the effect of these genes and their alleles on starch quality will be association-analyzed, including their interaction between two genes. The near isogenic lines of the main allelic variations will be developed through continuous backcrossing in the greenhouse and marker-assisted selection, and their effect on agronomic and starch quality traits will be evaluated. The implementation of this project will assign starch quality to starch synthesis genes and their alleles, characterize the influence of elite alleles on starch synthesis and yield development and establish molecular markers for those elite alleles. This work will dissect the genetic loci and their interaction conferring to starch quality, which could speed the molecular breeding of quality wheat in China.

小麦是最重要的粮食作物之一，淀粉品质的优劣直接决定了传统面食品的品质，而淀粉的合成由淀粉合成途径决定。本项目在对中国春淀粉合成途径基因的克隆及淀粉品质关联分析工作的基础上，计划对300份我国地方品种、不同时期育成品种多年多点的田间种植，测定淀粉品质参数（直链和支链淀粉含量及比例、糊化特性及粒径分布等），明确我国小麦品种淀粉品质的演变及分布；同时利用第三代单分子测序平台对所有关键基因进行测序，获得所有材料的基因组成及等位变异，关联分析不同基因及其等位变异的淀粉品质效应及互作效应；并对主要等位变异通过温室连续回交及标记选择创制近等基因系，明确各等位变异对农艺性状及品质性状的影响。本项目的实施将从整个淀粉合成途径的角度鉴定对淀粉品质有正向效应的基因及优异等位变异，明确优异等位变异对品质和产量的影响并建立分子标记，解析淀粉品质的遗传控制及其互作网络，为小麦优良品质育种的分子设计提供育种元件。

淀粉是小麦籽粒的重要组成部分，淀粉品质的优劣直接决定了面食的品质。本项目分析了我国主要小麦品种的淀粉品质状况，明确了我国小麦种质资源淀粉品质的状况，运用关联分析方法研究小麦淀粉合成途径基因的淀粉品质效应，开展了小麦中淀粉合成途径相关基因的组成及表达模式，挖掘了小麦种质资源中淀粉合成途径基因的等位变异，并通过创建近等基因系研究淀粉合成途径不同等位变异的功能，开展糯小麦分子育种及新品种培育。研究发现不同来源的小麦品种材料淀粉品质性状存在较大程度的变异，不同年份之间测定的结果相关性高，说明淀粉的品质性状主要受遗传调控；关联分析检测到104个和41个与淀粉品质峰值粘度相关的SNP位点，检测到32个和43个与淀粉粒径大小相关的SNP位点，在2A、2B、6A和7B染色体上存在一些与直链淀粉含量相关的SNP位点，在1A和6A上找到一些与总淀粉含量相关的SNP位点。转录组数据分析表明在小麦灌浆过程中大部分淀粉合成相关基因主要分为花后5天或10天达到表达高峰。从中国春小麦中克隆了29个SSRG基因，开发出了一种利用PacBio RS II技术批量检测多倍体中基因等位变异的方法。利用此方法，我们获得了324份小麦种质材料中22个SSRG基因的等位变异类型。根据鉴定到的等位变异类型，利用关联分析、近等基因系、转基因等手段深入地对TaAGPS-7A-TG变异类型与淀粉含量及千粒重之间的关系进行了研究，明确不同等位变异类型主要影响该基因编码蛋白的酶活；同时进行糯小麦分子育种工作，有两个新品系在参加河北省和山东省特用区域试验，有望在2020年审定。项目执行过程中，获得一大批重要的淀粉合成基因的等位变异，为进一步解析淀粉合成起到了关键作用，同时发表SCI论文5篇，中文核心期刊论文1篇，国内外会议摘要4篇，申请或获得授权专利3项，申请植物新品种权2项，2个糯小麦新品种参加区域试验并有望于2020年审定。