联合连锁和关联分析精细定位玉米灰斑病抗性主效QTL

Gray Leaf Spot (GLS) is a global destructive maize disease that results in significant maize yield loss in China especially in southwestern China. A total of 300 diverse inbred lines are selected to construct as the association mapping population in this project. The disease resistance phenotype is evaluated under 2 years by 2 locations environments, the population genetic diversity and structure is analyzed by the SNP makers of whole genomics and the SNPs correlated with GLS resistance are located by association analysis which is on base of whole genome screening. Then combined these SNPs with the detected resistant QTLs from previous linkage analysis, the common major QTLs are confirmed by using a joint linkage-association analysis, which are continued to fine mapping. Based on the detected major QTLs, potential candidate genes will be selected by taking advantage of bioinformatic analysis. Favorable alleles correlated to GLS resistance will be defined after evaluating gene function and estimating their genetic effects, which provides beneficial gene resources and lays a foundation for molecular breeding on maize GLS resistance.

灰斑病是全球主要的玉米病害，对我国特别是西南玉米生产危害严重。本项目以前期研究筛选出的300份具有广泛多样性的玉米自交系为材料，通过两年两点田间鉴定获得灰斑病抗性表型数据，结合全基因组SNP标记对群体遗传多样性及其结构进行分析，运用全基因组关联分析定位与灰斑病抗性表型关联的SNPs；在此基础上，与前期来自连锁群体检测出的抗性QTL进行整合，寻找共同的效应显著的QTL并进行精细定位；对检测到的与灰斑病抗性紧密关联的重要位点，结合生物信息学分析筛选候选基因，推测其功能和评估其遗传效应，发掘与灰斑病抗性相关的有利等位基因，为玉米抗灰斑病分子育种奠定基础。

灰斑病是全球主要的玉米病害，对我国特别是西南玉米生产危害严重。本项目采用一套包含热带、亚热带和温带的具有丰富多样性和广泛代表性的优良系组成的关联群体，运用当前完善的SNP分型技术和先进有效的关联分析方法，对灰斑病抗性位点进行全面挖掘；在此基础上与前期来自连锁群体检测出的抗性QTL进行整合，寻找共同的效应显著的QTL；并对检测到的与灰斑病抗性紧密关联的重要位点，结合生物信息学分析筛选候选基因。通过本项目的实施，首先筛选得到一批优良的灰斑病抗性玉米种质，可供下一步抗灰斑病玉米品种选育利用；同时筛选出一套质量高、多态性好的SNP核心标记，并利用这套标记成功将关联群体自交系划分为5个类群，并分析了这5个类群的遗传多样性和遗传距离；其次通过关联分析共检测到与灰斑病抗性显著相关的SNP标记共45个，其中重复检测到的标记共有32个，结合连锁定位结果发现其中有16个与其他研究检测出的抗性QTL位点重合或接近；并通过生物信息学分析筛选到了一个与灰斑病抗性显著相关的候选基因。本项目研究成果为玉米抗灰斑病分子育种奠定了一定的种质基础与基因资源。