Genetic diversity analysis of wild and cultivated alfalfa germplasm resources by isozyme markers

The genetic diversity of two wild alfalfa (Medicago sativa) accessions and 27 alfalfa cultivars were investigated using peroxidase, catalase and amylase isozyme polymorphism. A total of 30 stable bands were observed by three isozymes across 29 accessions, and six of which were specific bands which were only detected in Longdong wild alfalfa, Baicheng wild alfalfa, Langersteiner cultivar and Atlantic cultivar. The percentage of polymorphic bands (PPB) for peroxidase, catalase and amylase were 75.00%, 55.56% and 33.33%, respectively. The similarity coefficient among 29 accessions ranged from 0.633 to 1.000 and averaged at 0.867. Compared with the similarity coefficient values between wild alfalfa accessions and cultivars, the similarity coefficient values among cultivars were relatively higher. Cluster analysis indicated that 29 accessions can be divided into three defined groups at the similarity coefficient value of 0.772, and two wild alfalfa accessions were clustered in two independent groups, respectively. The position of Longdong wild alfalfa and Baicheng wild alfalfa in graph of principal component analysis was relatively isolated which suggest that wild alfalfa accessions had relatively distant genetic relationship with cultivars.