Genetic variability and structure of an important wild steppe grass Psathyrostachys juncea (Triticeae: Poaceae) germplasm collection from north and central Asia

Russian wildrye, Psathyrostachys junceus (Fisch.) Nevski, is an important wild steppe perennial grass, which is characterized by longevity and short robust rhizomes. It also has highly resistance in grazing and abiotic stress. In this study, the genetic diversity of eleven P. juncea wild germplasms from north and central Asia was investigated using AFLP markers. The P. juncea populations were divided into three clades in both UPGMA dendrogram and PCoA clustering corresponding to the three genetic memberships in STRUCTURE analysis. The genetic specificity of Xinjiang (XJ) populations was revealed by the highest N e (1.5411) and H j (0.3553) and their dispersion shown in UPGMA. High inbreeding coefficient (Wright’s F statistics, f = 0.496, F st = 0.128) was observed although a moderate degree of gene flow ( N m = 1.4736) existed, that may ascribe to habitat fragmentation or the low seedling recruitment, which ultimately resulted in decrease of population size and their genetic diversity. The key factors inducing moderate genetic differentiation detected in this study were isolation by distance (IBD), climatic variabilities and geographical barriers. All these results provide insights into the study of genetic status and germplasm collecting of Russian wildrye.