Plant & Animal Genome IX Conference

Workshop: Forage & Turfgrass
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TRANSGENIC APPROACHES TO HERBAGE QUALITY IMPROVEMENT IN TALL FESCUE AND ITALIAN RYEGRASS

Institute of Grassland & Environmental Research, Plas Gogerddan, Aberystwyth, SY233EB, UK.

The provision of a synchronous supply of protein and energy to the ruminant is a major determinant of feed quality, however this is not currently met with grass diets, resulting in inefficient N utilisation. Of particular concern is the low level of immediately availability energy in the form of soluble carbohydrates, the slow release of carbohydrates from the cell walls due to high levels of hydroxycinnamic acid dehydrodimer crosslinking, and high rates of plant mediated proteolysis. Genetic manipulation techniques have the potential for modifying the chemical composition of grass to improve the quality of these species as animal feed. In this paper we describe the introduction and expression of transgenes into Festuca arundinacea and Lolium multiflorum predicted to :

1. modify cell wall phenolic acid accumulation, crosslinking and lignification by expression of a bacterial enzyme [hydroxycinnamoyl-CoA hydratase/lyase (HCHL)] for the hydration and cleavage of the hydroxycinnamoyl-CoA thioesters, p-coumaroyl-CoA, caffeoyl-CoA and feruloyl-CoA to the corresponding hydroxybenzaldehydes.
2. reduce protein degradation during leaf senescence, by expression of the Agrobacterium isopentyl transferase gene under a senescence enhanced promoter and
3. modify the accumulation of soluble fructans, by short-sense co-suppression of a sucrose induced invertase/fructosyl transferase cloned from Lolium temulentum.