MOLECULAR ANALYSIS OF CELLULOSE BIOSYNTHESIS IN ARABIDOPSIS

Cellulose, an abundant, crystalline polysaccharide, is central to plan t morphogenesis and to many industries. Chemical and ultrastructural a nalyses together with map-based cloning indicate that the RSW1 locus o f Arabidopsis encodes the catalytic subunit of cellulose synthase. The cloned gene complements the rsw1 mutant whose temperature-sensitive a llele is changed in one amino acid. The mutant allele causes a specifi c reduction in cellulose synthesis, accumulation of noncrystalline bet a-1,4-glucan, disassembly of cellulose synthase, and widespread morpho logical abnormalities. Microfibril crystallization may require proper assembly of the RSW1 gene product into synthase complexes whereas gluc an biosynthesis per se does not.