Genes and proteins involved in cellulose synthesis in plants

In recent years, progress has been made in the identification of genes that encode proteins critical for the process of cellulose synthesis in plants. CesA genes encode proteins that are proposed to catalyze the glucan chain elongation step. CesA genes comprise a relatively large gene family in whic h some members may function in cell-type-specific expression, while others may serve as redundant genes mutually expressed within one cell type. In ad dition to CesA, evidence suggests the importance of other proteins in the p rocess. For example, a cytoskeletal-anchored form of sucrose synthase may p lay a role in channeling substrate, and other cytoskeletal proteins may be involved in directing the orientation of microfibril deposition. Recent evi dence suggests that a membrane-associated cellulase also plays some critica l role in the process of cellulose synthesis. While the power of molecular biology, isolation of specific mutants, and genomics are certainly leading to new insights into the process, the major challenge still facing the fiel d is to develop functional assays in which the entire process can be recons tituted and the specific roles played by each gene product clarified.