基于连锁作图与关联分析的南荻农艺和产量性状的QTL定位及优异等位变异发掘

Miscanthus lutarioriparius is the endemic plant in China which uses as a special economic crop for papermaking in the middle and lower reaches of the Yangtze River. It is also considered as a valuable potential of energy grass for its tall stalk, high fiber quality and high yield. China, especially in the middle and lower reaches of the Yangtze River, is the center of the origin and distribution of M. lutarioriparius, where an abundance of wild resources are living, providing a very favorable convenience for genetic research and breeding. In this project, we will construct a high density molecular map and conduct QTL analysis for important agronomic and yield traits based on the F1 population. Furthermore, we will introduce a set of core collection of M. lutarioriparius for association analysis of the traits described above. After comparing the two results of association analysis and QTL analysis, the fine location of yield-, agronomic-related genes /QTLs could be obtained. This study could reveal not only the characters of population genetics in M. lutarioriparius, but also the number, effect, action, location and allelic variation of yield-, agronomic-related QTLs. And we can explore the excellent germplasm and elite alleles in M. lutarioriparius. This project shows the values both in theory and application in Miscanthus researches for molecular marker assisted breeding, cloning and localization of important functional genes, as well as breeding new fiber varieties with high-yield, high-quality.

南荻是我国特有的芒属植物，作为长江中下游的特色经济作物供造纸之用；因其茎秆高大、纤维质量好、产量高，也是极具开发潜力的草类能源植物。长江中下游是南荻的起源与分布中心，有大量的资源分布，为南荻的遗传研究和育种改良提供了得天独厚的条件。本项目提出，采用南荻与荻杂交的F1群体，构建南荻高密度分子图谱，对南荻重要农艺与产量性状进行QTL分析；同时利用南荻核心种质，对上述性状进行关联分析；将F1群体的连锁作图的结果与核心种质的关联分析的结果进行比较，实现对南荻重要农艺与产量性状QTL的精确定位。研究结果既能揭示南荻的群体遗传学特征，又能明确南荻控制重要农艺和产量性状QTL/基因的数量、效应、作用方式、分布特点及等位变异情况，并从中发掘出优异种质资源与最优等位变异。项目的实施对于芒属植物分子标记辅助育种、重要功能基因的定位克隆，以及对于培育高产、优质的纤维作物新品种具有重要的理论与应用价值。

南荻为多年生高大型C4禾本科草本植物，是我国特有芒属物种，分布在长江中下游，被认为是最具发展潜力的第二代生物质能源之一。本项目收集、保存保存了长江流域506个居群的南荻的种质资源，并获得了相应的农艺性状、产量性状及物候期信息，同时构建具有嵌套结构的南荻核心种质。染色体倍性研究发现，南荻分为二倍体和四倍体两种类型。利用SLAF-seq简化基因组测序技术得到了141570个高一致性的群体SNP。通过基于全基因组的SNP（约14万个）的群体遗传学分析发现，二倍体荻和四倍荻表现出了与四倍体南荻更近的亲缘关系；二倍体南荻和四倍体南荻的遗传距离大于二倍体南荻与荻之间的遗传距离；四倍体南荻各地理居群间的遗传距离较二倍体南荻各地理居群间的遗传距离小；四倍体南荻各地理居群间有着更近的亲缘关系。利用90735个SNP进行 GWAS分析，共检测到213个与农艺性状、物候期以及地理分布相关的位点。此外，利用含有93个单株的F1群体，初步构建了包含266个AFLP标记的遗传图谱。研究结果对于南荻资源保护、分子标记辅助育种、重要功能基因的定位克隆、基因组结构与功能研究、以及对于培育高产、优质的优良纤维作物新品种，促进边际土地的合理开发利用等具有重要的理论与现实意义。