Genetic diversity and conservation of the endangered herb Dendrobium moniliforme based on amplified fragment length polymorphism markers

Abstract

Elucidation of the genetic diversity of an endangered species is a prerequisite for germplasm conservation. In the current study, 160 accessions representing 15 populations of the endangered orchid herb Dendrobium moniliforme (Orchidaceae) from different regions of Asia were collected to investigate its genetic diversity, using fluorescent amplified fragment length polymorphism (AFLP). It was found that D. moniliforme was characterized by high levels of genetic polymorphism (100% polymorphic fragments), low levels of total genetic diversity (Ht=0.1520), and moderate degrees of genetic differentiation among populations (FST=0.1026). STRUCTURE analysis showed that the 15 D. moniliforme populations formed three clusters corresponding to their geographical distribution. Analysis of molecular variance (AMOVA) revealed that only 19.20% of the genetic variation existed among populations, while 80.80% occurred within populations. The Mantel test demonstrated that genetic differentiation (FST) was correlated with log geographic distance when all sampled populations or all populations sampled from mainland China were analyzed, indicating the presence of isolation by distance (IBD). However, when populations sampled from southwestern China, central-southeastern China, and the Land Bridge were analyzed separately, IBD was no longer significant. These results suggested that IBD did exist in D. moniliforme, possibly due to the large geographic distance between populations and highly fragmented distribution of the species. Based on the obtained results, some useful conservation strategies were proposed for the effective and sustainable exploitation of D. moniliforme.