Cellulose synthesis and regulation in plants.

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The cell wall of plants is a complex and dynamic structure with many important roles in plant growth and development. It is impossible to consider a plant cell or the compendium of cells that make up a plant, if not in the context of their cell walls. Gaining a better understanding of how plants develop and grow therefore requires a knowledge of the mechanisms that control both cell wall assembly and integrity. Although the cell wall is made up of many different sugar polymers, the primary load-bearing polymer is cellulose. Despite its abundance and a number years of study, our knowledge of how cellulose is made and integrated into the growing wall is still very limited. The principle aims of my research program are to address how cellulose is synthesized and how this process is regulated. To determine the mechanisms of cellulose biosynthesis we are utilizing two model systems: a bacterium, Gluconoacetobacter xylinus, and a plant, Arabidopsis. The bacterial system has the advantage that cellulose synthase activity can be easily measured in vitro, something that has, so far, been difficult in plants. While Arabidopsis is amenable to genetic analysis, which allows us to genetically dissect cellulose biosynthesis in a plant. These two systems will be used to achieve three short-term objectives: (1) determine the structure-function relationships of cellulose synthase proteins, (2) analyze cellulose synthase complex structure and (3) identify potential cellulose synthase regulators. In combination with genetic analysis we will use modern cell biological and biochemical techniques to experimentally reach these goals. A deeper understanding of cellulose biosynthesis will provide the basis for understanding how long chain polymers are made in nature. In addition, this knowledge can be applied to creating or modifying natural polymers. Features of cellulose such as microfibril angle, which affects wood quality, the degree of polymerization (number of glucose units), and it’s crystallinity are all of economic interest.