Intermated recombinant inbred lines (IRIs) are a powerful tool for fine mapping and cloning of genes. Such population structures have been particularly helpful for cloning of genes in the model genetic plant Arabidopsis thaliana. IRIs or recombinant inbred lines (RILs) would be valuable for perennial ryegrass (Lolium perenne), but its allogamous character means that the construction of RILs is a difficult task. The international Lolium community would benefit from the development of such lines. The aims of the projects are to characterise the parental lines and initial generations at the (1) phenotypic, (2) molecular and (3) molecular cytogenetic level