Genetic variation and geographical divergence in Elymus nutans Griseb. (Poaceae: Triticeae) from West China

Elymus nutans Griseb. as an important forage grass and gene pools for improving cereal crops, widely distributes in west China. However, little is known about its genetic and geographical patterns. Inter-simple sequence repeat (ISSR) markers were applied to assess genetic diversity and geographical divergence among 63 E. nutans accessions from west China. The cluster analysis separated the accessions into several groups with geographical origins. The molecular variance analysis (AMOVA) showed that the proportion of variance explained by within- and among-geographical group diversity was 43.2% and 56.8%, respectively. Based on pairwise genetic distances (Φ_ST) between geographical groups, the relationships were congruent with the cluster of accessions. The distinct geographical divergence of E. nutans was revealed between Qinghai-Tibet Plateau and Xinjiang. The ecogeographical conditions such as climate and mountain ranges and elevation behaved as the crucial factors for genetic divergence. Furthermore, the study also indicated that Qinghai-Tibet Plateau might be the diversity differentiation center of E. nutans. The result will facilitate the breeding program and germplasm collection and conservation.