(608c) Understanding and Redesigning Secondary Cell Wall Deposition in Plants

The plant cell wall represents a large source of polysaccharides that could be used to substitute for sugar derived from starchy grains, which are currently used to feed and produce biofuels. This lignocellulosic biomass, largely under-utilized, is mainly composed of sugar polymers (cellulose and hemicellulose) embedded very strong aromatic polymer called lignin. Recalcitrant to degradation, lignin inhibits efficient extraction and hydrolysis of the cell wall polysaccharide and prevents cost-effective lignocellulosic-biofuel production. Unfortunately, lignin cannot simply be genetically removed without incurring deleterious consequences on plant productivity. The cost effectiveness of the conversion of the lignocellulosic biomass into sugars is still one of the major components to produce cheap biofuels. Therefore, strategies that can be used to reduce the lignin recalcitrance and that can increase polysaccharide deposition into the cell wall without altering plant growth should be developed.

We used synthetic biology to redesign cell wall biosynthesis and deposition without affecting the plant growth. We generated strategies to reduce lignin recalcitrance either by manipulating its spacio-temporal deposition or by manipulating its composition. We also reengineered the control of cell wall biosynthesis and used it to enhancing cell wall polysaccharides deposition and biomass density. Finally, several of these engineering strategies were combined and translated into an improvement in saccharification efficiency without affecting plant development. Developed approaches and preliminary data will be presented.

^¶This work conducted by the Joint BioEnergy Institute was supported by the Office of Science, Office of Biological and Environmental Research, of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231