Assessing genetic diversity of perennial ryegrass (Lolium perenne L.) from four continents by intersimple sequence repeat (ISSR) markers

Abstract

In this study, inter-simple sequence repeat (ISSR) markers were used to compare genetic diversity between commercial cultivars and natural germplasm which were obtained from Europe, Africa, Asia, and North America. There was a relatively high genetic variation in the whole collection judged by the polymorphism rate (97.16%), Nei's gene diversity (0.28), and Shannon's information index (0.44). Results indicate lower genetic diversity in commercial cultivars than natural germplasm. The European group showed the highest genetic diversity. The genetic distance (GD) between cultivars ‘Exacta’ and ‘ABT-99- 4.560’ was the closest (0.19), while largest GD occurred between ‘PI 632472’ and ‘PI 547390’ (0.85). Based on Jaccard’s similarity coefficient, 12 groups were distinguished with a cut-off point at 0.44. Using the concept of core collection, we suggested ‘Headstast 2’, ‘PI 598909’, ‘Catalina II’, ‘PI 538976’, ‘PI 598440’, ‘PI 610925’, ‘PI 598877’, ‘PI 516605’, and ‘PI 619554’ be included in a core collection of germplasm to accommodate maximum genetic diversity.

Key words: Genetic distance, genetic erosion, unweighted pair group method with arithmetic mean (UPGMA), cluster analysis, germplasm.