玉米人工合成群体S2遗传变异SSR标记评估

本研究利用SSR标记技术分析2个玉米人工合成群体S2分子水平的遗传变异,为群体合成及自交后代的选择提供一定理论依据。结果表明,40对引物在2个群体S2中共扩增出420个等位位点,每个SSR座位的等位基因数目为3～25个,平均为10.5个。GP-5S2的多态位点数、多态位点比例、基因型数、变异系数、基因杂合度等均大于GP-4S2,表明GP-5S2入选株系的遗传变异较GP-4S2大。遗传距离比较表明,不同群体S2间平均遗传距离大于群体内株系间平均遗传距离,群体内株系间平均遗传距离又远远大于株系内个体间平均遗传距离。根据遗传距离,可将60个单株分为5个大类10个亚类,GP-4S2部分株系和GP-5S2部分株系聚在同一亚类,表明GP-4S2和GP-5S2的部分株系可能有相似的遗传背景。因此,玉米人工合成群体亲本材料的选择应将田间鉴定与SSR检测结合,并根据育种目标确定合成材料的多少,而在自交后代选择中则应侧重系间选择。

Genetic Variation Evaluation Among the S2 of Synthetic Maize Populations by SSR Molecular Markers

In this study, the genetic variation among the S2 of 2 synthesized maize populations were evaluated based on the data of SSRs. On the 40 SSR loci, a total of 420 alleles were detected in the S2 of 2 populations. At each locus, 3 to 25 alleles could be detected, with an average of 10.5. The indexes including polymorphic site number, ratio of polymorphic sites, genotype number and mean gene heterozygosity in the S2 of GP-5 were all higher, so there was more genetic variation in the S2 of GP-5. The mean genetic distance between the S2 of GP-4 and GP-5 was higher than that among the 20 strains, and the latter was much higher than that among different individuals in the same strain. The S2 of 2 populations were classified into 5 groups and 10 subgroups according to genetic distance, some strains from the S2 of GP-4 and GP-5 were classified into a same subgroups, it indicated that these strains may have the same genetic backgrounds. It was necessary both to do field identification and SSR detection when selecting materials to synthesize maize population, and the number of materials was according to the breeding aim. When selecting lines from populations, strains selecting must be emphasized particularly.