Integrative approaches to determining Csl function

While there is an ever-increasing amount of information regarding cellulose synthase catalytic subunits (CesA) and their role in the formation of the cell wall, the remainder of the enzymes that synthesize structural cell wal l polysaccharides are unknown. The completion of the Arabidopsis genome and the wealth of the sequence information from other plant genome projects pr ovide a rich resource for determining the identity of these enzymes. Arabid opsis contains six families of genes related to cellulose synthase, the cel lulose synthase-like (Csl) genes. Our laboratory is taking a multidisciplin ary approach to determine the function of the Csl genes, incorporating geno mic, genetic and biochemical data. Information from expressed sequence tag (EST) projects has revealed the presence of Csl genes in all plant species with a significant number of ESTs. Certain Csl families appear to be missin g from some species. For example, no examples of CslG ESTs have been found in rice or maize. Microarray data and reporter constructs are being used to determine the expression pattern of the CesA and Csl genes in Arabidopsis. Mutations and insertion events have been identified in a majority of the g enes in the Arabidopsis CesA superfamily and are being characterized by phe notypic and biochemical analysis. While we cannot yet link the function of any of the Csl genes to their respective products, the expression and local ization of these genes is consistent with the expected expression pattern o f polysaccharide synthases that contribute to the primary cell wall.