Development of forage grasses with high quality and functionality based on genomic information of fructan

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Furctan, a polymers of fructose and a major component of water soluble carbohydrate (WSC), is accumulated in many plants, especially temperate grasses. Fructan plays important role as a regulatory substance of cytoplasm against osmotic stress caused by cold and drought. Fructan is also the main soluble carbohydrate digestible far animals. The increased level of fructan appears to improve abiotic stresses of plants as well as the nutritional value by animals.1. There were significant differences among cultivars, strains, ecotypes and related subspecies of cocksfoot (Dactylis glomerata L) for WSC and fiuctan contents. Crossing test demonstrated that Content of WSC was genetically controlled. A strain with higher content of WSC compared to standard cultavars was developed.2. Genes encoding fructosyltranferase involved with fructan biosynthesis (1-FFT,6G-FFT and 1-SST) were isolated from perennial ryegrass (Lolium perenne L) plants and identified using recombinant proteins expressed in the yeast Pichia pastoris. For 6G-FFT gene, present isolation was the first report in Gramineae. 6G-FFT gone was mapped on linkage group (LG) 3 and 1-FFT and 1-SST were mapped on LG 7. The increase in mRNA level of 1-FFT was obeserved in both leaves and crown tissues during cold acclimationn using Real-time RT-PCR method.3. QTLs for fructan content were not linked to the loci of fructan biosynthesis genes. Some of QTIs for winter hardiness in the filed were coincided with QTLs for c fructan content.4. We produced transgenic perennial ryegrass plants that overexpress wheat fuructan biosynthesis genes (1-SST and 6-SFT). Significant increases in fructan contents and tolerance to freezing damage were observed in transgenic plants. Overexpression of fructan biosynthesis genes appears to serve increased tolerance to freezing in plants.