Different evolutionary processes in shaping the genetic composition of Dendrobium nobile in southwest China.

Knowledge of population genetic structure and intrapopulation genetic variation is important for understanding population dynamics and evolutionary processes. Dendrobium nobile is an endangered traditional Chinese tonic medicine. In order to analyze the population differentiation and genetic diversity in D. nobile and propose proper conservation measurements, we genotyped 102 individual plants from 7 natural populations distributed across southwest China at 9 microsatellite loci. Seven pairs of genomic SSR primers were newly designed, and two pairs were chosen from the EST-SSRs. According to the results, the genetic process of D. nobile on Hainan Island and the Chinese mainland might be affected by different evolutionary processes, the genetic drift caused by founder effect has played an important role in shaping the genetic constitution of the Island population. The population of D. nobile in Hainan Island was highly differentiated and displayed low levels of genetic diversity. For the conservation management plans of D. nobile, we propose that individuals in Hainan Island with rare alleles need to be conserved with top priority, and those individuals with rare alleles and the most common alleles also should be concerned. The seven new microsatellite loci may be informative for further evaluation and conservation of the genetic diversity of D. nobile.