ABSTRACT
Objective:To explore the genetic diversity and population structure of <italic>Erigeron breviscapus</italic>， so as to provide a scientific basis for its resource protection and rational utilization. Method:Twelve pairs of simple sequence repeat（SSR） primers were screened out from 243 individuals in 16 natural populations to calculate the genetic diversity parameters of <italic>E. breviscapus</italic>， which were then subjected to principal coordinate analysis and cluster analysis. Result:Twelve SSR markers generated 209 alleles， with an average of 17.417 alleles per locus. Based on 12 SSR markers and 16 populations of <italic>E. breviscapus</italic>， the observed heterozygosity （<italic>H</italic><sub>0</sub>） values were determined to be 0.603 and 0.613， the expected heterozygosity （<italic>H</italic><sub>e</sub>）to be 0.658 and 0.659， and the Shannon's information index （<italic>I</italic>） to be 1.443 and 1.446， respectively. The Wright's fixation index （<italic>F</italic><sub>st</sub>） was 0.123 and gene flow （<italic>N</italic><sub>m</sub>） was 2.077. Analysis of molecular variance （AMOVA） and genetic differentiation revealed that genetic variation within populations was the main source of total variation. The Nei's genetic distance and genetic identity coefficients were within the ranges of 0.107 （YA and XY）-0.713 （SZ and XZD） and 0.490 （SZ and XZD）-0.899 （YA and XY）， respectively. As demonstrated by the principal coordinate analysis and cluster analysis， the 16 populations of <italic>breviscapus </italic>were divided into two clusters. Conclusion:The genetic diversity of <italic>E. breviscapus</italic> was relatively high and there existed certain genetic differentiation and gene flow within and among populations. The genetic variation was mainly present within populations. All these have provided reference for subsequent study on good germplasm selection of <italic>E. breviscapus.</italic>