Ecological genetics of Reaumuria soongorica (Pall.) Maxim. population in the oasis–desert ecotone in Fukang, Xinjiang, and its implications for molecular evolution

Using inter-simple sequence repeat (ISSR) markers, studies were performed to characterize the population genetic diversity and structure of Reaumuria soongorica (Pall.) Maxim. in the oasis–desert ecotone in Fukang, Xinjiang. Eleven primers were screened to amplify DNA sequences from 132 individuals, which corresponded to seven subpopulations. Totally, 176 loci, all of them polymorphic, were detected, and the percentage of polymorphic bands (PPB) was 100%, indicating a relatively high genetic diversity within the R. soongorica population. According to the hierarchical analysis of molecular variances (AMOVA), the analysis of Shannon's diversity and Nei's analysis of gene diversity, the percentages of genetic variation among subpopulations were 15.87%, 16.28% and 14.58%, respectively, which meant that 83.72–85.42% of total genetic variation occurred within subpopulations. Besides, POPGENE analysis also revealed a relatively high gene flow (Nm = 2.9290) among subpopulations. Correlation analysis showed that there existed no significant correlation between the ISSR-based genetic diversity of the seven R. soongorica subpopulations and their ecological factors (mainly in soil) (P > 0.05). However, on the other hand, Mantel test revealed a significant correlation between inter-subpopulation genetic distances and geographic distances (r = 0.637, P < 0.01), indicating that geographic distance was among the important factors affecting the population genetic structure of R. soongorica. Meanwhile, a comparative analysis was performed between the present ISSR-based and the previously published RAPD-based results, and revealed obvious discrepancies, implying the different evolutionary patterns of the genomic regions sampled by ISSR and RAPD markers.