Genetic Diversity And Geographic Differentiation Of Kirengeshoma Palmata (Hydrangeaceae) Endemic To Eastern Asia

Kirengeshoma palmata is a perennial herb endemic to Eastern Asia. The main distribution of wild populations is in the hills in the East China, the Korean peninsula, and the Japan Archipelago(CKJ). The Kirengeshoma palmata is in severe danger, of which the distribution and populations size are quite small. The Quaternary ice-age cycles have played an important role in the genetic structure and current distribution of Kirengeshoma palmata. The analysis was carried out based on ISSR and cpDNA atpB-rbcL intergenic spacer.The genetic diversity of Kirengeshoma palmata is quiet high(in species level PPF = 92.13%, h = 0.8045,Ï€= 0.002266; the population average PPF = 49.60 %, h = 0.6577,Ï€= 0.001455). According to ISSR analysis, 55.97% of the variance occurred within populations and that was 58.67% based on cpDNA, while the differentiation between populations was quite large. The genetic diversity of population KC (Japan) and TM (China) were relative high, and that of population BU (Korean) was lowest.Both the cpDNA and ISSR analysis suggested the existence of two phylogeographical groups in K. palmata, i.e. China-Japan vs. Korea. Population BU from Korea had a unique ancestral haplotypes (H2), and the most common haplotype (H1) was shared between Chinese and Japanese materials. cpDNA haplotype relationship was'star-like', with many rare tip haplotypes linked to the ancestral interior haplotypes, H1 and H2, respectively. Such a pattern and Tajima's D test both suggested a population bottleneck in situ followed by demographic range expansion.Hence the inference was made that the possible glacial refuge of K. palmata, was located in TM-HS China, KC Japan, and BU Korean, respectively. In consequence, we hypothesized that diversification of K. palmata populations may have begun under interglacial or post-glacial conditions when higher sea levels of the East China Sea isolated these regions.