Abstract
In Northern Tunisia, perennial ryegrass (Lolium perenne L.) and tall fescue (Lolium arundinaceum = Festuca arundinacea Schreb.) are two important grasses for forage and soil erosion prevention. To analyse the genetic diversity within and between these indigenous forage grasses, this study was performed on a set of eight spontaneous accessions collected from different geographic sites in the North and North-West of Tunisia using Amplified Fragment Length Polymorphism markers (AFLP). One hundred eighty four polymorphic bands (PPB = 100%) have been generated-by four EcoRI-Msel AFLP primer combinations. Among totally polymorphic bands, specific markers of each species were generated: 29 AFLP markers varying between 380 bp and 780 bp were detected for tall fescue and 13 AFLP markers ranging between 200 bp and 940 bp were recorded for perennial ryegrass. Cluster analysis of the polymorphic markers was performed with NTSYS-pc software package. Results permitted the differentiation of these two species and exhibited a high degree of diversity within and between accessions. Four individuals were clearly distinguished from Lolium-Festuca pool and could be supposed as natural hybrids revealing both Lolium and Festuca specific markers. Shannon index revealed a higher level of intra-population variation as compared to the inter-population diversity. This result may be explained by the allogamous mating system of both species. Analysis of the geographic distribution suggested two independent gene funds corresponding to each species with a substantial gene flow, particularly at Hammam Bourguiba region. The observed genetic diversity can be used for the implementation of conservation strategies and breeding programs to improve forage crops.