Genetic diversity of 42 alfalfa accessions revealed by SSR markers

In order to reveal the genetic diversity of alfalfa germplasm resources, the genetic diversity of one wild and 41 cultivated alfalfa accessions were analyzed using SSR markers. The results showed that there were totally 231 alleles and 163 polymorphic alleles generated from these 42 alfalfa accessions by 15 SSR primers. The mean values of polymorphic percentage, Nei’s gene diversity and shannon’s information index for these 15 primer pairs were 71.55%, 0.210 0 and 0.326 3, respectively. The similarity coefficient of accessions ranged from 0.641 to 0.913 with an average of 0.791, and the mean value of similarity coefficient between wild alfalfa accessions and cultivars was lower than that among cultivars. Cluster analysis classified accessions into five defined groups at the genetic similarity value of 0.778, among which Longdong wild alfalfa, CW 200 and CW 787 were clustered into three independent groups, indicating that these accessions had relatively distant genetic relationship with the others. According to principal component analysis, the accessions can be divided into four groups, and the accessions in the Ⅰ and the Ⅱ groups had relatively distant genetic relationship with those in the Ⅲ and the Ⅳ groups. In conclusion, the alfalfa accessions used in the present study had relatively high genetic diversity, and some of which had relatively independent genetic characteristics.