Study of genetic structure and diversity in cultivated alfalfa populations (Medicago sativa L.) using ISSR markers

The use of genetic resources in crop improvement requires accurate study of genetic diversity in plant populations. Therefore, genetic structure and diversity of 80 alfalfa (Medicago sativa L.) genotypes belong to 8 population were assessed using ISSR markers. Sixteen ISSR primers amplified a total of 117 loci, out of them 91 were shown to be polymorphic among and within populations. PIC (Polymorphic information content) values for primers ranged from 0.65 (Primer UBC849) to 0.93 (primer 443), averaging 0.77. Populations were grouped in three main clusters using UPGMA algorithm based on Nei genetic distance coefficient. The maximum and minimum amount of genetic distances between populations were 0.128 (Gharayonjeh-malekkandi and Hamedani) and 0.054 (Turkey-sakuel and Baghdadi), respectively. Mean of heterozygocity varied from 0.267 (Baghdadi) to 0.309 (Turkey-sakuel and Mahalie-esfahani) with an average of 0.285. Analysis of molecular variance (AMOVA) showed that 91% of the total genetic variation was attributed to intra-population variance. Cluster analysis based on complete linkage algorithm using Dice similarity coefficient identified 6 heterotic groups among studied genotypes. Populations with enough genetic distance or genotypes belong to different heterotic groups could potentially introduced as crossing parents in alfalfa breeding programs.