Molecular genetic diversity within and among German ecotypes in comparison to European perennial ryegrass cultivars

Perennial ryegrass (Lolium perenne L.) is the most important grass species for temperate grassland agriculture. The level and distribution of genetic variation in gene bank ecotype collections is still largely unknown but of great interest for the planning of breeding programmes. The objectives of this study were to (i) assess the molecular variance and population structure of German ecotypes at the regional and population level, (ii) assign ecotypes to germplasm pools and (iii) compare the relationship between German ecotypes and previously investigated European cultivars of perennial ryegrass. A total of 22 ecotypes originating from three geographic areas in Germany, each with a sample size of 20 individual plants, were investigated with 156 polymorphic RAPD markers. Genetic distance among ecotypes ranged from 0.27 to 0.48. An analysis of molecular variance (AMOVA) revealed a much larger variation within populations (71%) than among them (29%). Ecotypes from North Germany were significantly different from those of South and Middle Germany. Thus, two distinct emiplasm pools could be identified. The 22 ecotypes and 22 previously investigated cultivars shared 98% of the molecular variance.