Studies On Genetic Diversity Of Alpine Cushion Plant Thylacospermum Caespitosum

Cushion plant community that grows within the environment with extremely severe climate and most infertile soil,is most sensitive to the global climate change,and plays important role in sustaining species diversity,stability and function of alpine ecosystem.Therefore,there're great scientific values to explore the formation mechanisms and functions of alpine cushion plant community.Thylacospermum caespitosum is a kind of typical cushion plants.In this study,the author analyzed population genetic diversity and phylogegraphy of 4 natural Thylacospermum caespitosum populations were analyzed by AFLP molecular markers and cpDNA sequences markers,aiming to explore the level of genetic diversity and the spatial distribution patterns of Thylacospermum caespitosum and the information of geological history change and providing the basic information of population genetics for designing the genetic resource conservation stratagy of Thylacospermum caespitosum.The major findings are as follows:(1)We acquied 56 individuals of Thylacospermum caespitosum that is a representative species of cushion plants from 4 populations.The populations were named GS,GL,XJ and QH.(2)8 primer combinations were screened from 64 EcoRI/Msel primer combinations.They can produce clearly and highly polymorphic bands.The genetic diversity of 38 samples of Thylacospermum caespitosum was analyzed.8 primer combinations were taken to generate 888 clearly identifiable bands of 38 individuals from 4 populations,and there are 824 polymorphic bands.The highest genetic variation was in the population GL(h=0.2298,1=0.3462),the population QH(h=0.1392,I=0.2082)had the lowest genetic variation.The 4 populations of Thylacospermum caespitosum had a high level of gene diversity,distributed Mainly within(66.16%)rather than among(33.84%)populations.The gene flow among populations was at a high probability(Nm=1.0051).The genetic identity was in the range of 0.7051-0.9314.The result of UPGMA cluster analysis showed that 4 populations could be divided into three groups:GS and GL;XJ;QH.(3)We amplified and sequenced two cpDNA fragments(rps16 and psbB-psbH),The results show that there are 4 chlorotypes in this species,and these chlorotypes were clustered into 2 lineages;AMOVA showed that cpDNA genetic diversity were distributed evenly both within populations and among populations,and mainly among populations;PERMUT simulations detect significant phylogeographic.Three kinds of neutrality test were analysed,the results show that this species might experienced population shrinkage during its history of evolution.Based on the analysis of genetic diversity and regulations of geographical on cushion plant Thylacospermum caespitosum,the author revealed the The ecological distribution and the molecular evolution mechanisms of Thylacospermum caespitosum.There're great scientific values to explore the formation mechanisms and functions of alpine cushion plant community.