Genetic diversity and population structure of the medicinal orchid Gastrodia elata revealed by microsatellite analysis

The wild resources of Gastrodia elata are currently threatened with extinction due to over-harvesting because of their high medicinal value. Genetic diversity plays a key role in the survival of endangered orchid species. In this study we investigated the genetic pattern in eight microsatellite loci within eight G. elata populations from central China. Compared with the other orchids, G. elata showed a low level of genetic variation within populations (HE = 0.356-0.622). The main factors responsible for the genetic pattern were the plant's inbreeding system due to mating within clone patches, and the genetic bottlenecks and genetic drift caused by a long-history over-collecting. The significant heterozygote deficit was detected in all the populations. The F statistics calculated by different approaches consistently revealed a clear genetic differentiation among populations, contributing about 20% of the total gene diversity. The results are discussed in relation to both in situ and ex situ conservation efforts of the species. The populations with a high level of genetic diversity or with great genetic distinction were identified, which should be a high priority for conservation managers.