Genetic diversity of the natural populations of Arabidopsis thaliana in China.

Although extensive studies have been conducted on the genetic structure of Arabidopsis thaliana (A. thaliana) populations worldwide, the populations from China have never been studied. In this study, we collected 560 individuals from 19 natural populations of A. thaliana distributed in East China along the lower reaches of the Yangtze River, and two populations from northwest China (Xinjiang Province). We adopted two kinds of molecular marker, inter-simple sequence repeats (ISSRs) and random amplified polymorphic DNA (RAPDs) to investigate the genetic diversity within and among populations, and the correlation between the genetic and geographic distances. Thirteen ISSR primers produced 165 polymorphic bands (PPB) (96%) and 11 RAPD primers produced 162 polymorphic bands (98%) in about 560 individuals. The two marker systems generated similar patterns of genetic diversity in these natural populations. The AMOVA analysis indicated about 42-45% of the total genetic variation existed within populations, and found possible geographic structure. The Mantel test revealed a significant correlation between the geographic distance and the genetic distance of these populations in general. A close genetic relationship was found among four populations in the Jiangxi Province, and these always appeared clustered together as a monophyletic group in unweighted pair-group method with arithmetic averages dendrograms based on both ISSR and RAPD data sets. Based on the observation of recolonization and extinction of naturally distributed populations of A. thaliana, and the pattern of their genetic differentiation, the distribution of this species in China might be a result of natural dispersal under the strong influence of human activity.