Genetic differentiation in endangered Heptacodium miconioides Rehd. based on ISSR polymorphism and implications for its conservation

Genetic diversity and genetic differentiation within and among nine populations of Heptacodium miconioides Rehd., an endangered plant endemic to China, were investigated using inter-simple sequence repeat (ISSR) markers. High genetic diversity at species level was revealed (percentage of polymorphic loci P = 78.31%, Nei's gene diversity h = 0.2469 and Shannon information index I = 0.3760, respectively). However, the genetic diversity at population level was relatively low (P% = 27.22%; h = 0.0880; I = 0.1328). High genetic differentiation among populations was detected based on AMOVA (FST = 0.6630). The estimated Nm from FST was 0.2538. There was significant correlation between genetic and geographic distance among the populations studied. It indicated that the current genetic structure of H. miconioides might be mainly due to the mating system and genetic drift following the isolation and fragmentation of small populations as a result of human destruction. Based on the genetic data, efficient and practical conservation strategies were proposed to preserve this endangered species.