Genetic Diversity Analysis Of Caragana Microphylla Lam. And Caragana Stenophylla Pojark In Inner Mongolia Plateau

Caragana microphylla and Caragana stenophylla are perennial and Xerophytic shrubs of Legume Caragana Fabr,and they has widest distribution and largest number in Inner Mongolia Plateau.The typical species of pinnately compound leaf group,C.microphylla,is diploid plant,while typical species of pseudo-palmately compound leaf group,C.stenophylla,is tetraploid plant.They have many excellent characteristics,such as drough and cold resistance,wind erosion and drought resistance,they also can prevent sand fixation and maintain soil and water,it is of great significance in environmental protection.In this study,the genetic diversity,genetic structure and genetic differentiation of 7 C.microphylla and 8 C.stenophylla populations distributed naturally in Inner Mongolia Plateau were analyzed by SSR markers.The aim of this study is to investigate the adaptation of two Caragana species to the environment and and to provide genetic evidence for the evolution of the genus Caragana.And combined genetic diversity with meteorological and soil factors to analysis the influence of environment on genetic diversity.The main results are as follows:1)The morphological and soil characteristics of two species:The crown and plant height of C.microphylla is significantly higher than C.stenophylla.The soil nutrient content of C.microphylla is significantly higher than that of C.stenophylla,and there is significant difference in soil pH of two species.Correlation analysis showed that:the crown of species with average annual precipitation,effective accumulated temperature,average relative humidity,0-20cm soil total nitrogen content,soil C/P and soil C/N have significant correlation.Plant height with effective accumulated temperature,0-10cm soil organic carbon and soil N/P have significant correlation.Therefore,in addition to genetic factors,meteorological and soil factors are also the main factors which affect two species's morphological characteristics.2)SSR analysis of genetic diversity:Total Nei's genetic diversity index and Shannon's information index of C.stenophylla is 0.2100 and 0.3436,while in C.microphylla is 0.1885 and 0.3087,it showed that the genetic diversity of C.stenophylla is higher than C.microphylla.Genetic differentiation of C.microphylla and C.stenophylla respectively are 0.2725 and 0.3074,66.79%and 69.12%genetic differentiation occurred within populations.The gene flow are large in C.microphylla and C.stenophylla,respectively is 1.3345 and 1.1264,Frequent gene exchange means that genetic differentiation among population was not caused by genetic draft.The above data show that C.stenophylla has more aboundant genetic diversity and genetic differentiation than C.microphylla,it means that C.stenophylla is more adaptable to environment than C.microphylla.3)Analysis of correlation between genetic diversity and ecological factors:Mantal test show that there is no significant correlation between genetic distance and geographic distance(P<0.05).In stepwise regression analysis,Genetic diversity of two Caragana species was significantly correlates with average temperature,0-1 Ocm soil total phosphorus and soil total nitrogen(P<0.05).4)Cluster analysis results:From the east to the west,C.microphylla and C.stenophylla gradually clustering,populations with similar geographic distances will be firstly clustered together.