| Sophora alopecuroides is a perennial rhizome herb of Sophora in the Fabaceae family.It has drought,cold,alkali and wind and sand resistance,it is a dominant species and pioneer species in desert and semi-desert areas in northwest China.So far,domestic and foreign researches on S.alopecuroides mainly focus on the fields of phenotypic characters,chemical constituents,pharmacological activities,stress tolerance physiology,seed germination characteristics and germplasm resources investigation.However,the study of population genetic structure and dynamic historical change is fewer.In this study,we constructed the phylogenetic study of 222individuals from 49 populations of S.alopecuroides in Inner Mongolia Plateau and its adjacent areas,with the maternally inherited cpDNA fragments（psb A-trn H,trn S-trn G and trn K）and niche modeling.It is used to explore its genetic diversity and population genetic structure,to speculate the population dynamic history and potential refuge under the climatic fluctuations of Quaternary glacial period,and further to analyzed the spatial and dynamic history S.alopecuroides,to provides scientific basis for biodiversity conservation and speciation mechanism research of S.alopecuroides.The main results are as follows:⑴A total of 7 haplotypes（H1-H7）were detected in 49 populations of S.alopecuroides;The haplotype diversity（HD）was 1.57218,the nucleotide diversity（π）was 3.40102 and the average nucleotide difference index（K）was 1.57433.It indicated that the genetic diversity of S.alopecuroides was relatively high,and the genetic diversity index varied greatly among different populations.Molecular variance analysis（AMOVA）showed that the genetic variation of S.alopecuroides existed mainly within populations（67.12%）,the significant genetic differentiation existed among populations(FST=0.32880,P<0.01)and the gene flow between populations was more frequent（Nm=1.05）.⑵Population genetic structure analysis showed that S.alopecuroides had no obvious pedigree geographical structure(GST<NST,P>0.05).There was a significant positive correlation between geographic distance and genetic distance（r=0.046,P=0.01）,but the correlation coefficient was small,suggesting that geographical distance may not be the main factor of genetic differentiation among populations of S.alopecuroides.The Structure analysis showed that 49 populations of S.alopecuroides could be divided into two genetic lineages（Group 1 and Group 2）,and their distribution patterns did not correspond to geographical regions.⑶Population dynamic history analysis showed that Tajima’s D=4.54672,Fu and Li’s D*=1.32263,Fu and Li’s F*=2.99207,Fu’s Fs=22.171 of S.alopecuroides were significant positive values（P<0.05）,SSD and HRagwere low（P<0.05）.The mismatch distribution showed a bimodal curve,which indicated that population of S.alopecuroides did not experienced recent expansion.⑷Niche modeling analysis showed that temperature and precipitation were the main factors affecting the distribution of S.alopecuroides,and the history of distribution expansion consistant with the theory of"glacial contraction and interglacial expansion",which experienced a dynamic historical of first small scale contraction and then small scale expansion.North China,northwest China,south of Taihang Mountains,north of Greater Khingan Mountains and marginal zone of Changbai Mountains may be the main glacier refuges of S.alopecuroides. |
