Plant & Animal Genomes XI Conference

January 11-15, 2003
Town & Country Convention Center
San Diego, CA

Workshop: Barley
            

A GENOMICS APPROACH TO THE DISSECTION OF CELL WALL BIOSYNTHESIS IN BARLEY.

Department of Plant Science, University of Adelaide, Waite Campus, Glen Osmond, South Australia, 5064, Australia

The international research trend towards functional genomics of cereals has been demonstrated by the high levels of commercial and public investment in this technology around the world. Access to and control of the technology, together with the discovery of gene systems that will flow from cereal genomics work, is seen as a key to the future of cereal production. We have focused on the biosynthesis of cell walls, which are primary determinants of seedling growth and development. Walls are also key components in the resistance of plants to pathogens, in human nutrition, and in determining many key quality characteristics of the mature grain. Subtle variations in the fine structures of major wall polysaccharides can have a dramatic effect on the functional/rheological properties of cereal-based products. Despite their importance in cereal growth and end-product quality, factors that control the synthesis of wall polysaccharides in developing grain and in young seedlings have not been defined, mainly because the key synthase enzymes are difficult to purify. The relatively recent identification of higher plant cellulose synthase (CesA) and cellulose synthase-like (Csl) genes opens the way for a genomics approach to the discovery of other polysaccharide synthase genes that mediate cell wall biosynthesis in cereals. We have isolated six CesA genes and representatives of the CslA, CslC, CslD, CslE, CslF and CslH families from barley. A major challenge is to develop rapid procedures for defining the function of these genes, which cannot simply be inferred from sequence similarities with other, well-characterized genes. Transiently induced gene silencing methods, based on dsRNAi technology, have been used to define functions of the synthase genes. Analysis of extensive EST databases reveals that polysaccharide hydrolases are also likely to play a central role in cell wall polysaccharide biosynthesis.