Phylogeography of East Asian Lespedeza buergeri based on genetic variations in chloroplast and nuclear ribosomal DNA

초록

The warm-temperate regions of East Asia are the hotspot for plant species richness and endemism. However, genetic structure and diversity for the plant species in that region is still poorly understood, particularly with regard to southern coastal area of Korea. Therefore, we investigated the genetic diversity and phylogeographic structure of Lespedeza buergeri. The species is known from China and Japan, and recently reported from southern coastal area of Korea. We analyzed DNA sequences from two non-coding regions of chloroplast DNA (cpDNA) (rpl32-trnL and psbA-trnH ) and ITS of nuclear ribosomal DNA (nrDNA) of 142 individuals from 13 populations. A total of 32 cpDNA haplotype (chlorotypes) and 8 ribotypes (ribotype) were detected. In a statistical parsimony network, chlorotypes were formed as an asterisk form and any significant geographical clades were not shown. The ancestral chlorotype is detected in China and southern area of Japan, but most chlorotypes are specific for each population. Especially, no chlorotypes of Korean populations were shared with other regions. No ribotype shared among regions were detected, but populations in central area of Japan shared ribotype A and populations in China shared ribotype E. Consequently, molecular data suggested that the current Korean populations of L. buergeri would be derived from those of East China Sea Basin and southern Japan (Kyushu). We discussed on genetic structure and historical migration of the species as a member of warm-temperate element in East Asia.