To study population structure within non -heading Chinese cabbage crops ,78 non-heading Chinese cabbage varieties grown in a large planting area in China were collected .Their DNA polymorphisms were analyzed by a set of SSR markers and their population structure were clustered by Structure 2.1 software according SSR data. Out of SSR primer 120 pairs,21 pairs origining 10 linkage groups of Brassica rapa were screened out with polymor-phism and 56 alleles in the 78 varieties were generated.The average number of alleles per SSR locus was 2.7.The 56 markers were imported in the program structure to identify subpopulations ,resulting in 4 subgroups in the 78 va-rieties.Subpopulations S1 and S2 mainly included 49 Pak choi varieties from different provinces in southern or northern China.Seedling Chinese cabbages were mainly distributed in subpopulation S 3 and S4.Wutacai varieties were mainly distributed in subpopulation S1 and S4.The genetic backgrouds of Caixin varieties were relatively com -plicated.The relationship between material grouping and geographical origin was very clear in subpopulation S 2. This result indicated an obvious population structure within non -heading Chinese cabbage ,which established the ba-sis for utilizing the current germplasm resources to guide breeding and discovering the new genes .% 为了研究不结球白菜内部的群体结构，从全国搜集了78份广泛种植的蔬菜用不结球白菜品种，使用 SSR标记对其进行多态性分析，并利用 Structure 2．1软件统计分析标记数据划分群体结构。结果表明，初筛出的21对多态性 SSR 标记覆盖了白菜10个连锁群，在78份材料中扩增共产生了56个等位基因变异，平均每个 SSR 标记产生的等位基因数目为2．7个。 Structure 分析表明，所选的不结球白菜可分为4个亚类群，S1和 S2亚类群主要集中了来自于南北方各省份的49份普通白菜，苗用大白菜主要分布在 S3和 S4亚类群，乌塌菜主要分布在 S1和 S4亚类群，菜心的遗传背景比较复杂；材料的类群划分与地理来源的关系在 S2亚类群表现的较为明显。结果表明，不结球白菜内部存在着明显的群体结构，为合理利用现有的种质资源指导育种和进行新基因的挖掘奠定了基础。
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