Cellulose biosynthesis and deposition in higher plants.

The plant cell wall is central to plant development. Cellulose is a major component of plant cell walls, and is the world's most abundant biopolymer. Cellulose contains apparently simple linear chains of glucose residues, but these chains aggregate to form immensely strong microfibrils. It is the physical properties of these microfibrils that, when laid down in an organized manner, are responsible for both oriented cell elongation during plant growth and the strength required to maintain an upright growth habit. Despite the importance of cellulose, only recently have we started to unravel details of its synthesis. Mutational analysis has allowed us to identify some of the proteins involved in its synthesis at the plasma membrane, and to define a set of cellulose synthase enzymes essential for cellulose synthesis. These proteins are organized into a very large plasma membrane-localized protein complex. The way in which this protein complex is regulated and directed is central in depositing cellulose microfibrils in the wall in the correct orientation, which is essential for directional cell growth. Recent developments have given us clues as to how cellulose synthesis and deposition is regulated, an understanding of which is essential if we are to manipulate cell wall composition.