Genetic Diversity Of Taiwania Cryptomerioides Based On NSSR And CpSSR Molecular Markers

Taiwania crytomerioides is an ancient, endangered species endemic to China. According to preliminary investigations, the existing wild T. crytomerioides in the mainland of China are only6,000trees, which are in the urgent need of conservation.This project selected representative wild T. crytomerioides populations as the research object, which was used field surveys to detect the present condition of natural T. crytomerioides resources. It is the first time that we used several molecular markers together including nSSR and cpSSR, combined with the principle and methods of population ecology and modern genetics to discuss genetic diversity, genetic structure, gene flu and population evolution history of T. crytomerioides populations. In this project we investigated the conservation status of T. crytomerioides sufficiently, and clarified their endangered genetic mechanisms and reasons. The results would supply the scientific proof for population recovery and the genetic management of ex-situ and in-situ conservation of T. crytomerioides.There are some main conclutions of our research:(1) The genetic diversity and genetic structure of six natural populations of T. crytomerioides were investigated using nuclear simple sequence repeat (SSR). Of the87primers screened,5primers were generated66stable, distinct and highly polymorphic bands. The average observed and expected heterozygosities were0.2313and0.3696,respectively.The result of POPGENE indicated that T. crytomerioides had a low level of genetic variation.There was a certain level of genetic differentiation among six populations and most of the genetic differentiation occurred within populations. The UPGMA clustering and Mantel test showed that there was no significant correlation between the geographical and genetic distance (r=0.5391, P=0.03). Based on these findings, we propose appropriate conservation strategies for this endangered species.(2) The genetic diversity and genetic structure of six natural populations of T. crytomerioides were investigated using chloroplast simple sequence repeat (cpSSR). Of the65primers screened,10primers were generated46stable, distinct and highly polymorphic bands and22haplotypes.As the result showed,all the studied T crytomerioides populations had their unique haplotypes,which might have been caused by long-distance isolation.The result of POPGENE indicated that T. crytomerioides had a low level of genetic variation at the species (Nei’s gene diversity H=0.1501,Shannnon’s information index1=0.2596) and population levels (PPB=23.91%, H=0.0622,I=0.0988). There was a certain level of genetic differentiation among six populations and most of the genetic differentiation occurred within populations (97.68%).The UPGMA clustering and Mantel test showed that there was no significant correlation between the geographical and genetic distance (r=-0.0372, P=0.25)...