Diversity Of Ssr And Influence Of Climatic Factors In Stipa Breviflora Population In Inner Mongolia

Stipa breviflora,dominant species of warm desert steppe,is an important pasture resource,which widely distributed in Inner Mongolia Plateau,Ordos Plateau,Loess Plateau,Qinghai-Tibet Plateau and Xinjiang province.Owing to the effects of human disturbances and climate changes,desert grasslands suffered from serious degeneration,loss of biodiversity,and weakened ecosystem services.Therefore,the changes of genetic diversity and genetic structure of S.breviflora populations were discussed to reveal the main factors affecting their genetic diversity and genetic differentiation,which is positive to understand the maintenance mechanism of genetic diversity for the main established plant species in desert steppe.At the same time,it is valuable for the restoration of degraded desert grassland,biodiversity conservation and other practices.In our study,we used 15 SSR loci based on population genetics methods to characterize the genetic diversity,genetic structure of S.breviflora populations collected along the east-west direction of the Inner Mongolia Plateau.And the genetic differentiation levels and gene flow levels among populations were examined to reveal the influencing factors.The main conclusions were showed as following:(1)The population genetic diversity based on SSRUsing the SSR-PCR reaction system,12 SSR primers with clear and highly polymorphic bands were screened out,and 166 polymorphic bands were amplified,with an average of 13.8 articles per primer amplification.At the species level,the expected heterozygosity(He)of S.breviflora was 0.7258,Nei's diversity index was0.7251,and Shannon's diversity index(I)was 1.7384,indicating that S.breviflora was rich in genetic diversity.(2)The genetic structure and genetic difference of S.brevifloraSTRUCTURE clustering results showed that the 21 S.breviflora populations were divided into three groups.Most of the genetic variation originated from individuals within the population,and the genetic variation between populations and between groups were small.According to F-statistical analysis,the genetic differentiation coefficient(Fst)was 0.0822 and the gene flow was 2.7924.It indicated that S.breviflora was at moderately genetically differentiated level,the gene flow was adequate in this study,and there was no genetic differentiation caused by genetic drift.(3)The role of climate and geographic factors in space genetic divergenceThe results of Mantel test showed that the genetic distance of S.breviflora populations were not related to geographical distance,but environmental distance.Both temperature and precipitation factors were significantly correlated with the genetic distance of the S.breviflora populations,indicating that differences in temperature and precipitation were the main causes of genetic differentiation in S.breviflora populations in Inner Mongolia Plateau.