玉米大斑病抗性基因Ht3、HtN精细定位及分子辅助聚合育种研究

Northern leaf blight is one of the important diseases in maize, it seriously restrict the development of the corn industry. Breeding cultivation of resistant varieties is the most economical and effective way to prevention and treatment of disease occurrence. Mining and utilization of resistance genes is a necessary prerequisite for rapid breeding of resistant varieties. Northern corn leaf blight resistance gene is divided into quantitative and quality resistance. Quality control by dominant gene have Htl, Ht2, Ht3, and HtN. They are inherited independently, and the resistance gene have a cumulative effect. these genes only coarse positioning the maize chromosomes 2.07,8.05,7.04,8.06 region, and it has not been cloned. On the basis of the preliminary work, we plan to fine mapping of resistance gene Ht3, HtN with the simplified genome deep sequencing technology and DH groups as the mapping population. This lay the necessary foundation for gene cloning. And the closely linked molecular marker can be used for detection of resistant resources.Thus by means of assisted selection by closely linked molecular marker, we can carry out the disease-resistant gene molecular marker-assisted pyramiding breeding, it will build and improve of a number of semi-exotic composite germplasm ,create a suitable technology for corn leaf blight disease resistance traits.

大斑病是重要的玉米病害之一，严重制约着玉米产业发展。选育栽培抗病品种是防治病害发生最经济、有效的方法，而抗病基因的挖掘与利用是快速选育抗病品种的必要前提。玉米大斑病抗性基因分为数量抗性和质量抗性两种。其中，受显性基因控制的质量抗性有4个，分别为Htl、Ht2、Ht3、和HtN。它们是相互独立遗传的，且这些抗性基因具有累加效应，目前这些基因只粗略定位于玉米染色体2.07、8.05、7.04、8.06区域，至今没有被克隆的报道。多年接种鉴定发现含Ht3、HtN基因的材料在东北地区高抗大斑病，项目组计划采用高通量测序技术，利用构建的含有Ht3和HtN的DH群体对Ht3、HtN基因分别进行精细定位，开发与抗病基因紧密连锁的分子标记，为基因克隆及开展分子标记辅助育种研究奠定必要的基础，同时构建和改良一批半外来的复合种质；创立一套适于玉米大斑病抗病性状改良的育种技术体系。

本项目利用SLAF-seq（Specific-Locus Amplified Fragment Sequencing）技术对玉米A619Ht3/辽3162的BC1遗传分离群体（2个亲本和50+50的混池）进行关联分析，共获得159,637个SLAF标签，其中多态性SLAF标签有19,443个，多态性比例为12.18%。通过对多态性SLAF标签的分析，SNP方法共关联到60个SLAF标签，共定位到2个区域。关联区域大小约为21.98Mb，关联区域内有251个基因。Euclidean distance方法共关联到60个SLAF标签，共定位到3个区域。关联区域大小约为29.44Mb，关联区域内有310个基因。SNP_index关联到2个区域，分别进行KEGG、GO和COG功能注释分析，共有177个基因注释到KEGG通路，36个基因注释到GO Term，310个基因注释到COG Class。Euclidean distance关联到3个区域，分别进行KEGG、GO和COG功能注释分析，共有40个基因注释到KEGG通路，216个基因注释到GO Term，79个基因注释到COG Class。SNP方法和ED方法定位到的区域有交集，其交集在6号染色体上，6号染色体上的交集是115345到4952322，大小为4.84Mb，其间定位到的基因有107个。该研究成果为进一步进行玉米大斑病抗病基因研究提供了理论和数据支撑。