Population Genetics And Landscape Genomics Of The Rare And Endangered Plant Tetrastigma Hemsleyanum Based On SLAF-seq Technique

Tetrastigma hemsleyanum belongs to the genus Tetrastigma of the Vitaceae family,and is a rare and endangered medicinal plant widely distributed in subtropical China.Its origin can be traced back to the Early Pleistocene,and provides a perfect opportunity for studying adaptive evolution or local adaptation.This study utilized simplified genome sequencing technique and genome-wide high-density SNP markers,and integrated approaches from population genomics and landscape genetics to systematically investigate the population dynamics and potential ecological adaptation process within T.hemsleyanum.The main results are as follows:（1）the results of genetic diversity and population structure analysis show that T.hemsleyanum has a relatively high genetic diversity(P=0.8534,Ho=0.0834,He=0.2298,P_i=0.2307,F_IS=0.6051)at the species level;the modern range of this species comprises two major lineages,Southwest（SW）and Central-South-East（CSE）China,and the latter were further spitted into three sublineages,corresponding to the clades of Central China（CC）,East China（EC）and South China（SC）;（2）based on F_STgenetic differentiation（Bayescan,h-FDIST2,Bayenv X^TX and Selestim）and genotype-environment association analysis（Bayenv and Baypass）,a respective of 752 and 527candidate loci potentially related to growth and development,biosynthesis,and metabolism were identified,of which the number of sites correlated to Potential Evapotranspiration Seasonality,altitude,and Precipitation of Wettest Month are the largest,which may imply that these environmental variables play a crucial role in the evolutionary adaptation of T.hemsleyanum;（3）Redundancy analysis（RDA）、Generalized Dissimilarity Modelling（GDM）and Gradient Forests（GF）were used to analysis the response pattern of genetic variation with environmental gradients of T.hemsleyanum,and the results revealed that the geographic factor is the most significant var iable that affects the intraspecific genetic differentiation in all populations.However,in comparison with the large-scale spatial range,the importance of climate variables was enhanced in local scales（within lineages）.The two geographic lineages display different response patterns to environmental gradients,and the growing degree‐days and Precipitation of Coldest Quarter are the climatic variable that contributed the most to the genetic differentiation within the CSE and SW lineages,respectively;（4）finally,based on the non-adaptive risk（RONA）analysis,the adaptive potential of T.hemsleyanum to future climate and environmental changes is predicted.The results indicate that the Southwest lineage has better adaptive potential,while the populations located at the eastern margin of the distribution range（such as the Wuyi population in Zhejiang Province and the Jianyang population in Fujian Province,etc.）undertake a higher risk of extinction.In summary,this findings highlights importance of environment driven adaptation in shaping the genetic differentiation of T.hemsleyanum,which laid foundation for understanding the adaptive genetic basis,evolutionary adaptation and protection strategies of broad-leaved evergreen species under global climate change.