'Plant Breeding: Sustaining the Future' Abstracts of the XVIth EUCARPIA Congress, Edinburgh, Scotland, 10-14 September 2001 MOLECULAR MARKERS FOR IMPROVING NUTRITIVE VALUE IN PERENNIAL RYEGRASS M. HUMPHREYS, L. TURNER Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, Ceredigion, SY23 3EB., UK

Perennial ryegrass is the most important forage grass for temperate livestock production. It shows considerable genetic variation for water-soluble-carbohydrate (WSC) content which provides the energy required for efficient rumen fermentation leading to improved utilisation of forage protein. An F₂ family, comprising 194 individuals with a 27% variation in WSC, has been used to develop a framework map using RFLPs, AFLPs, SSRs, isozymes and functional probes. Seven linkage groups were identified which align with the International ryegrass reference map. QTL analysis has revealed genome areas that have major roles in regulating carbohydrate content and relationships with other nutritive value traits have been established. Groups of genotypes have been selected for the presence/absence of markers linked to specific QTL and their progeny are being evaluated.