Genetic diversity analysis of perennial ryegrass germplasm by SSR molecular markers

Perennial ryegrass (Lolium perenne) is widely grown as a forage and turf grass species. To understand the genetic diversity of perennial ryegrass germplasm, we used SSR markers to analyze 10 self-bred lines of L. perenne and 75 germplasm materials collected from 23 different countries. The results showed that 91 polymorphic bands were amplified using 26 pairs of SSR (simple sequence repeats) primers, accounting for 69.5% of all amplified bands. The PIC (polymorphic information content) value of each SSR pair varied between 0.156～0.722 with a mean value of 0.455. The genetic similarity index of the 85 germplasm materials was 0.700～0.900. The NTSYS phylogenetic analysis showed that by setting the cutting value of the genetic similarity coefficient (GS) at 0.738, five clades could be clustered from the 85 materials. Comprehensive cluster analysis and Structure population genetic structure analysis revealed that there was no significant association between the genetic relationships and the geographic origins of these germplasm materials. The results of this study provide a theoretical foundation for germplasm evaluation and parental plant selection in breeding programs.