Plant & Animal Genomes XIII Conference

January 15-19, 2005
Town & Country Convention Center
San Diego, CA

Functional Genomics Of Cell Wall Biosynthesis In Barley

Antony Bacic² , Peter Langridge¹ , Edward J Newbigin² , Geoffrey B. Fincher¹

¹  Australian Centre for Plant Functional Genomics University of Adelaide, Waite Campus Glen Osmond, SA 5064 Australia

²  Australian Centre for Plant Functional Genomics, School of Botany, University of Melbourne, Parkville, VIC 3010 Australia

The cell walls of the Triticeae are characterized by relatively high levels of (1,3;1,4)-beta-D-glucans and arabinoxylans, together with cellulose and smaller amounts of xyloglucans and glucomannans. The major wall polysaccharides of the starchy endosperm affect grain quality through their effects on parameters such as loaf volume and crumb texture, wort and beer viscosity, digestibility of stock foods and dietary fibre.
Functional genomics technologies have been used to characterize candidate genes for synthases involved in the assembly of cellulose, (1,3;1,4)-beta-D-glucans and (1,4)-beta-D-xylans in barley. These candidate genes include members of the cellulose synthase (CesA), cellulose synthase-like (Csl) and callose synthase (Gsl) gene families. Further, genes encoding enzymes responsible for the addition of arabinosyl and glucuronosyl residues to the (1,4)-beta-D-xylan backbone and for re-modelling the polysaccharides during wall maturation have been examined.
Transcript analyses, using both quantitative PCR and DNA chip technologies, have shown pronounced correlations between the expression patterns of the candidate genes and the appearance of specific wall polysaccharides in a range of barley tissues. Immunocytochemical techniques have been applied for the high resolution detection of the polysaccharides in tissue sections. Barley genetic resources and the rice genome sequence have also been used for the identification of candidate genes, which have been subjected to gene silencing and gain-of-function experiments to determine their role in wall biosynthesis.