Genetic variation patterns of Medicago ruthenica populations from Northern China
As a promising legume for forage in arid and semi-arid areas, Medicago ruthenica (L.) Trautv. is widely distributed in northern China. For this study, twenty four accessions from northern China were analyzed by allozyme and microsatellites markers to determine its genetic variation patterns, two assays were found different in the amounts of polymorphism. Higher amounts of polymorphism were detected by microsatellites. For allozymes and microsatellite markers, mean expected heterozygosity (He) of 24 populations ranged from 0.160 to 0.485 and 0.274 to 0.5316 respectively. Mean observed heterozygosity per locus (Ho) of 24 populations was 0.422 for allozymes and 0.4149 for simple sequence repeats (SSR) markers. For allozymes, average interpopulation genetic diversity (Hs) was 0.2733 and average intrapopulation genetic diversity (DST) was 0.0473, mean coefficient of gene differentiation for loci (GST) at the population level was estimated 0.1813. According to GST, gene flow at population level was 1.4427 for allozymes and 1.2040 for SSR markers, which indicated there was definite gene flow between populations. Low differentiations among populations at allozymes (FST = 0.1719) and SSR markers (FST = 0.1816) means genetic variations is mainly lied in populations. The results showed there was high genetic diversity in M. ruthenica populations.
Key words: Medicago ruthenica, genetic diversity, allozyme, micro-satellite, North China.