微卫星分子标记在木薯种质资源遗传分析中的应用

Evaluation on Microsatellite Molecular Genetic Diversity of Cassava Germplasm Resources by SSR Marker

采用28对微卫星标记(SSR)对我国现存89个木薯品种进行遗传多样性分析,共获得93个基因位点,其中多态性位点88个,平均多态性水平为94.6%。运用Gensury软件统计了总群体的遗传杂合度(Ht)、群体内的平均基因多样性(Hs)、群体间的基因漂变频率(Dst)和遗传分化系数(Gst=Dst/Ht),结果表明,群体的基因杂合度居中,群体内部遗传多样性较小,存在一定程度的基因漂流;进一步用NTSYS-pc计算品系间的遗传相似系数,获得UPGMA聚类图,表明品系间遗传相似系数变化范围为0.430￣0.952,以平均遗传相似系数0.58为阈值,所有品系分为4类(A,B,C和D组)。其中A组最大,有72个品系,包括3个亚组:A1为国内收集的农家品系,A2品系均来自哥伦比亚,A3为一个独立品系。说明木薯引入中国已经发生了一些遗传分化。进一步分析表明,分组后每组内部的遗传多样性指数在0.20￣0.30之间,其组内的遗传多样性贫乏。

An analysis of genetic diversity for 89 original cassava accessions collected in China by using SSR markers yields 93 diversity locus, among which 88 have an average diversity of 94.6%. Ht, Hs, Dst and Gst, the four parameters, have been calculated by using Gensury software. It is shown that the gene diversity in the total set of populations is not large, and the average gene diversity within populations is smaller. There is some kind of gene differentiation. The genetic similarity coefficient and UPGAM tree among all accessions based on NTSYSpc calculation tool revealed that the GS change from 0.430 to 0.952. When GS equal to 0.58, all accessions can be ascribed into 4 groups： A, B, C, D. The largest group A included 72 accessions should be divided into 3 sub-groups： A1 depends on almost all native races, A2 contains clones shipped from Colombia and A3 is a single genotype. It is indicated that the cassava germs early immigrated into China already make some gene differentiation. And there are new evidences showing that gene diversity in each group is very low, among 0.20-0.30. The paper also takes a discussion on key SSR analysis skills in cassava and breedingutilization of cassava germplasm in China.