Abstract

Rheum tanguticum Maxim. ex Balf. is an important medicinal plant endemic to Qinghai-Tibetan Plateau. Inter-simple sequence repeats (ISSR) was used to assess genetic diversity of four R. tanguticum populations from Golog Tibetan Autonomous Prefecture, Qinghai, China. Fifteen efficient primers were screened and amplified 342 polymorphic bands out of which 340 (PPB = 99.42%) were polymorphic. Nei's gene diversity (H_e) and Shannon index (I) revealed a high level of genetic diversity with H_e = 0.2385 and I = 0.3794. Further, the coefficient of gene differentiation (G_st) and gene flow (N_m) were 0.2054 and 1.9347, respectively. Analysis of molecular variation (AMOVA) showed that most of the genetic variation (71.48%) occurred within populations, whereas the variance among populations was only 28.52%. The UPGMA tree illustrated that populations from JK and DK were genetically close related, while the population from DW was found to be the most diverse from the other three. The high genetic diversity implies that the wild resources of this species could be restored soon if an appropriate and efficient protection strategy was employed. Our results also provided a useful method for evaluating the genetic diversity of R. tanguticum using ISSR markers which was suitable for further investigation.

Key words: Rheum tanguticum, inter-simple sequence repeats (ISSR), genetic diversity, population.