芝麻种质资源SSR标记遗传多样性与群体结构分析

Genetic Diversity and Population Structure of Germplasm Resources in Sesame (Sesamum indicum L.) by SSR Markers

利用42对具明显多态性的SSR引物,分析国内外545份芝麻品种的遗传多样性和群体结构。结果检测到106个等位变异位点,引物多态位点范围为3~9个,平均为3.8个/引物,Y1994引物的等位位点最多,为9个。引物Shannon’s信息指数（I）范围为1.4834~0.1233,平均值为0.6450;多态信息指数（PIC）范围为0.7481~0.0516,平均值为0.4092,平均杂合度（He）为0.1162。UPGMA聚类、二元主成分及群体结构分析结果基本一致;供试545份芝麻资源可被分为3个UPGMA组群,在群体结构上分为3个亚群;芝麻资源整体遗传分化较小,亲缘关系较近。中国7个生态群种质相似系数范围为0.9811~0.5462,东北西北等区域资源与黄淮、江汉、华中华南等区的亲缘关系较远;国外7个生态群相似系数为0.9726~0.7442,非洲区与日本区种质亲缘关系较近,与中国资源亲缘关系较远。中国种质资源遗传基础较为狭窄,遗传多样性与地理分布不完全相关,而国外资源遗传多样性丰富。在今后芝麻育种工作中,应加强国外资源的引进与利用,并注重国内不同类群资源利用,拓宽我国芝麻品种遗传基础。

A total of 545 sesame accessions, including domestic and foreign germplasm resources, were analyzed systematically with 42 SSR primer pairs. The results showed that 106 allele bands were detected among the sesame accessions, and the Shannon’s information index （I） was 0.4092. Analysis results of UPGMA clustering, two-dimension principal components and population structure were basically consistent; 545 varieties were divided into three groups in UPGMA dendrogram or three subgroups in population structure. There were the lower genetic differentiation coefficient and the closer sibship in worldwide sesame. The similarity coefficient of seven ecological groups in China ranged from 0.9811 to 0.5462, and there was no close genetic relationship between varieties from northern regions and other regions in China. The similarity coefficients for foreign varieties were from 0.9726 to 0.7442, and the genetic relationships of varieties from Africa zone was close to those from Japan zone, but not from China. It showed that the genetic basis of varieties from China was relatively narrow, and the genetic diversities of varieties were not completely related to geographic distribution, but the genetic diversities of varieties from abroad presented abundance. Therefore, the introduction of foreign resources should be reinforced, and the domestic resources from different regions should be utilized in the future sesame breeding.