Inter-Simple Sequence Repeat (ISSR) Markers Revealed Genetic Diversity and Population Structure Among 9 Wild Species of Clematis L

To analyze the genetic diversity of 9 species of Clematis from 31 different populations, we extracted DNA by the improved CTAB method, used ISSR-PCR for amplification, and then selected 9 primers with clear amplified bands from amongst 220 primers. A total of 127 clear bands were amplified, of which 126 were polymorphic bands, yielding a ratio of 99.2%. The polymorphism information index (PIC) of the primers ranged from 0.9326 to 0.9649. The Nei’s genetic diversity index (H) was 0.2750, the total gene diversity (Ht) was 0.2845, and the genetic differentiation coefficient (Gst) was 0.6696, indicating high genetic differentiation among populations of Clematis. After cluster analysis, the 31 Clematis populations were divided into 3 categories. Principal coordination analysis (PCoA) of 9 Clematis species then showed that the genetic relationship between samples of the same Clematis germplasms was closer than that of samples from the same region. The mantel test revealed a significant positive correlation between genetic distance and geographical distance among the populations. The population clustering results are broadly consistent with the clustering graphs of UPGMA and PCoA. We can conclude the polymorphism of the 9 primers is good, and that the genetic diversity of 31 Clematis populations is rich. Individual Clematis germplasms are closely related and will gather together preferentially.