中文摘要：

[目的]利用高密度SNP标记解析骨干亲本京411的遗传结构，并研究其根系性状遗传特征，为培育高产广适性品种奠定基础。[方法]选用京411及其14个衍生品种（系），包括衍生一代6份，衍生二代8份，每品种选取饱满且大小一致的种子在发苗网上生长6 d，每份材料选取大小一致的幼苗转移至培养盘，每个培养盘种植3次重复，连续培养15 d后测定苗期根部性状的最长根长、侧根长、主根长、总根长、侧根表面积、主根表面积、总根表面积、总根尖数和根系干重。利用90K SNP芯片分析京411及其衍生后代群体的遗传结构和遗传区段传递，结合逐步回归分析定位苗期根部性状基因，探讨京411携带的优异根系基因在衍生后代中的分布。[结果]京411衍生群体平均遗传相似性为57.9%，该亲本与其衍生一代和衍生二代相同的等位变异频率分别为63.9%和67.9%，显著高于理论值。在A、B和D基因组间的相同等位变异频率分别为62.2%、61.3%和74.3%。京411的侧根和根尖数均优于其衍生品种，衍生品种的主根长和根干物质重量等性状的改良较为显著。以已有定位信息的SNP标记与根系性状进行逐步回归分析，共发掘出35个根系性状位点，3DL和5BL上携带控制根长性状的主效位点，分别与SNP标记wsnp_Ex_c1032_1972861和BS00100708_51关联，可用于京411衍生群体中分子辅助选择。来自京411的26个位点对根部性状起正向效应，中麦175和CA0958携带正向效应区段最多，占正向效应位点总数的73.1%。[结论]传统育种对地上部农艺性状的选择，可有效促进地下根系的改良，相当于对优异性状遗传片段的聚合。在京411衍生群体中，中麦175是针对骨干亲本遗传改良最成功的品种，不仅携带较多的京411优异根系基因，而且其主要根系性状、产量表现及广适性均优于京411。

英文摘要：

[Objective]The breeding program in crop root plays an important role in determining yield potential and broad adaptation. Jing 411 as one of the most important elite parents has been widely used in the Northern Winter Wheat Region. Understanding the principal components and detecting the root traits loci in Jing 411 will provide important information for future genetic improvement by high density SNP markers.[Method]The core parent Jing 411 and its 14 derivative varieties and lines including six derivative and eight varieties in the first and second generations were used in present study. The uniform grains of each variety were selected for germinating in seedling plate for 6 days, and then six healthy and consistent plants were selected to culture 15 days in cultivating plates. Every variety with three replicates in each cultivating plate was planted in nutrient solution. Nine root parameters including maximum length root, length of branch root, length of main root, total length of roots, surface area of branch roots, surface area of main root, surface area of total roots, number of total root tips, and root dry weight were measured after 15 days of culture. The genetic structure and components of Jing 411 and its derivative populations of different generations were compared. The whole-genome association mapping was employed to identify the chromosome region controlling seedling root traits loci using 90K SNP markers. [Result]The averaged genetic similarity index was 57.9% among Jing 411 and its derivatives, and the clustering results for these genotypes were generally in consistent with their pedigree. Jing 411 had the same allele ratios of 63.9% and 67.9% to its first and second generation derivatives, respectively. Most of Jing 411 derivatives were obtained from the second generation by backcrossing with the elite parent or its derivatives, and the contribution of Jing 411 was higher than theoretical expectation. On A, B and D genomes, the same allele ratios from the elite parent were 62.2%, 61.3% and 74.3%,