Genetic diversity in Tunisian perennial forage grasses revealed by inter-simple sequence repeats markers

• Seven ISSR primers generate 199 polymorphic ISSR markers.
• Data provide evidence of a large genetic diversity among and within populations.
• This analysis shows significant differentiation of the two species.
• Genetic differentiation among populations is attributed to low gene flow.
• Clusters are independent from the geographic origin and climatic conditions.

The analysis of genetic variation within and among eight populations of perennial species Festuca arundinacea and Lolium perenne was based on 199 polymorphic inter-simple sequence repeat markers of which 49 (24.6%) were specific to perennial ryegrass, and 31 (15.5%) discriminate tall fescue. Shannon's index and AMOVA partition revealed that in each species the most ISSR variation occurred between populations, rather than within populations. The analysis of the genetic structure of populations showed a significant differentiation of these two species. The Bayesian analysis isolated each tall fescue population, whereas perennial ryegrass individuals were divided into two groups. The observed clustering was independent of the geographical origin of populations and climatic conditions, supporting a high adaptive power aptitude to large scale of ecological variations. Close molecular homology between cultivars and wild populations suggested a substantial gene flow.