Carbohydrate metabolism plays a central role in the provision of substrates for bioenergy and biorenewables. The concentrations of readily fermentable carbohydrates in grasses are highly significant as a determinant for biofuel production. Further understanding of the regulation of carbohydrate metabolism in grasses is required for future plant breeding of energy grasses and to optimise the harvesting, storage and processing of biomass for efficient recovery of bioenergy/ natural products. Key objectives in this work are an understanding of (1) plant carbon partitioning/accumulation, at whole plant, tissue and sub-cellular levels, with emphasis on starch and sucrose in Miscanthus and on fructan, starch and sucrose in Lolium; and (2) expression of candidate genes and their association with QTL for non-structural carbohydrates. This work supports and integrates with studies on the identification of QTL for sugar metabolism (initially on Lolium, and later extended to Miscanthus) and the validation of QTL by marker-based test crosses. Transformation will be used to test gene function; candidate genes will be mapped and related to QTL on the Lolium and Miscanthus genetic maps.