Genome Mapping and Molecular Breeding in Lolium and Festuca

Of the 8 species in the genus Lolium, Italian ryegrass (Lolium multiflorum Lam.), is one of the most important cool-season forage grasses and is the most widely cultivated annual forage grass in Japan. Another important Lolium species is perennial ryegrass (L. perenne L.); it is cultivated mainly for forage and turf in the British Isles, Europe, USA, Australia, and New Zealand. Both Italian ryegrass and perennial ryegrass are outcrossing species, and each has a relatively large genome (1 C � 2000 Mb). In recent years, many molecular marke rs, including amplified fragment length polymorphism (AFLP) markers, restriction fragment length polymorphism (RFLP) markers, simple sequence repeat (SSR) markers, and expressed sequence tag (EST) markers, have been developed for Italian ryegrass and perennial ryegrass, and several types of molecular linkage map have been constructed. In addition, markers closely linked to genes for resistance to diseases such as crown rust, gray leaf spot, and bacterial wilt have been identified. Quantitative trait loci (QTLs) for flowering time, winter hardiness, forage quality, and other important traits have also been analyzed. In this paper, we review recent progress in genome mapping and QTL analysis in Lolium spp. We also include studies on tall fescue (Festuca arundinacea Schreb.) and meadow fescue (F. pratensis Huds.), two species closely related to Lolium.