Genetic Diversity And Phylogeographic Study Of The Endangered Species Platycrater Arguta (Hydrangeaceae) Endemic To The Sino-Japanese Region

Platycrater arguta is monotypic genus,which represents a deciduous shrubs of the temperate deciduous forests of Sino-Japanese floristic region.Accordingly,determination of genetic diversity,population structure and glacial refugia are of crucial importance in order to understand the historical processes which Platycrater arguta has undergone.Our present work investigated the phylogeography of Platycrater arguta including 4 populations from China and 2 populations from Japan.The analysis was carried out based on cpDNA psbA-trnH and trnD-trnE intergenic spacer.Genetic diversity and population structure were detected and the possible glacial refugia of Platycrater arguta were inferred in combination with the ecological investigations,geological history,fossil record and the pollen-based vegetation simulation during the last glacial maximum(LGM).Consequently,conservation strategies are proposed.The main conclusions of our research:4 populations from China and 2 populations from Japan(71 individuals)were analyzed using cpDNApsbA-trnH and trnD-trnE intergenic spacer.25 variation sites were detected,which gave rise to a total of 16 cpDNA haplotypes.Nucleotide diversity and haplotype diversity areπ=0～6.51×10^-3and h=0～0.756 respectively. In ZX Jiangxi China,5 haplotypes were found,Four haplotypes are unique to ZX.In BS China,4 haplotypes were found,All haplotypes are unique to BS.In OB Japan detected only one haplotype.AMOVA revealed variation exist among populations(Fst =58%)is higher than variation exist within populations(Fst=42%).High genetic differentiation was detected(Fst=0.580,Gst=0.530)among populations. Haplotype phylogenetic analysis and nested clade analysis revealed that three potential refugia existed during the last glaciation:ZX and BS in China,WS in Japan.Neutrality test and mismatch distribution neither support any significant postglacial population expansion.The genetic structure detected in this study is critical for the establishment of the conservation strategies.In order to conserve the genetic resources of Platycrater arguta,we propose that the most desirable populations for the in situ conservation are those in ZX,BS and WS.Because of the high genetic diversity these populations are desirable for an ex situ core collection.In addition the collection of germplasm from different populations is necessary during ex situ conservation in order to preserve the high genetic diversity of Platycrater arguta.