Research Of The Genetic Diversity And Parentage Analysis On The Endangered Species Pseudolarix Amabilis

Pseudolarix amabilis is a single species of plant which is an endemic to China. It has an important significance in the phylogenetic development of gymnosperms, paleoecology and paleoclimate research. But with the reasons of geological changes, ecology deterioration, low quantity and the low ability of natural regeneration, it becomes the endangered species. The genetic differential assessment in or between the populations of endangered species has become a most important content in the conservation genetics. The research of the mating system of the endangered species also has an important significance in the biodiversity management, which can make the right strategy of monitoring biodiversity and to support guide to manual breeding. In these years, more and more researches aim at genetic diversity and gene flow. But most of them use the isozyme marker to make analysis. Only a few researchers use the technic of SSR genetic marker due to the high expenditure and strict requirement of operation. Now in China, the SSR technical is still in the beginning process. In the gene flow research, the focus is in the analysis of the pollen dispersal and the parentage analysis of seeds. For the parentage analysis of seedling, most researches are lack of ability to distinguish the sex of parents pair. In this research, we use SSR locus to analyse the genetic differential and mating system in a natural Pseudolarix amabilis population. We also use nuclear SSR and cpSSR to analyze the parentage of the seedlings in the population. The results are as follows:(1) We successfully selected 5 nuclear SSR locus and 2 cpSSR locus for the Pseudolarix amabilis. We detected an average of 8.6 alleles in the population and the number of alleles per locus comes from 5 to 14. We also find the exclusion probability of the SSR locus higher than 0.99.(2) This natural Pseudolarix amabilis population has a high genetic diversity. The Shannon diversity index of the population was higher than 1.2. The Ho and He of the population was 0.639 and 0.614, respectively.(3) In the analysis of genetic diversity of this population, we found the F index was higher than zero and the average Ho was lower than He, which means the population is lack of heterozygosity. This result can be explained by the disturb of the villagers activity who were living near the population.(4) We found this natural Pseudolarix amabilis population has a mixed mating system. The multi locus outcrossing rate was 0.846 and the single loci outcrossing rate was 0.792, the inbreeding index was 0.054.(5) In this research, we use 5 nuclear SSR locus and 2 cpSSR locus to successfully analyze the parentage of the seedlings in this population. Of the total 120 seedlings, there are 85 individuals found the complementary parents and 36 individuals found single parent. Only 4 individuals have not found their parents and we assumed that with the 17 individual who only found their fathers in the population together, they may source from other populations by seeds flow.