Genetic diversity and population structure of Rheum tanguticum (Dahuang) in China

BACKGROUND: Wild Rheum tanguticum (Dahuang in Chinese) has becoming endangered in China. This study aims to examine the genetic structure and genetic diversity of R. tanguticum within species, and the genetic differentiation within and among populations in China. METHODS: The variability and structure of 19 populations of R. tanguticum were investigated by their chloroplast DNA matK sequences. The genetic diversity index was calculated by Dnasp, PERMUT, and Arlequin 3.0 software, and a neighbor-joining (NJ)-tree was constructed by MEGA 5.0 software. RESULTS: Fifteen haplotypes were obtained based on the matK sequence analysis. The mean genetic diversity within species was 0.894, and the genetic variability among populations (67.6%) was relatively higher than that within populations (13.88%) according to the AMOVA and PERMUT analyses. The NJ-tree and a pairwise difference analysis indicated geographical isolation of R. tanguticum. The gene flow among populations was 0.05, indicating a genetic drift among some populations, which was also confirmed by the NJ-tree and haplotype distributions. Furthermore, a mismatch distribution analysis revealed the molecular evolution of R. tanguticum. CONCLUSION: Genetic diversity among and within populations of R. tanguticum in China was demonstrated.