Molecular Analysis of Cellulose Biosynthesis in <i>Arabidopsis</i>

TLDR

Cellulose is a key structural polysaccharide in plants, and its microfibril crystallization likely depends on proper assembly of the RSW1 gene product into synthase complexes. Map‑based cloning and biochemical analyses show that the Arabidopsis RSW1 locus encodes the catalytic subunit of cellulose synthase; the cloned gene rescues the temperature‑sensitive rsw1 mutant, and the mutant allele reduces cellulose synthesis, accumulates noncrystalline β‑1,4‑glucan, disassembles synthase complexes, and causes widespread morphological defects.

Abstract

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