PhD: Duke University
Postdoctoral Training: USDA and University of California Berkeley
Grasses have for millennia provided humans with food, feed, and fiber. In addition, grasses are increasingly becoming a source of fuel. To replace a substantial portion of our current petroleum usage, species such as switchgrass (Panicum virgatum) and Miscanthus (Miscanthus x giganteus) are being developed as dedicated bioenergy crops. The photosynthetically fixed carbon in plant tissues can be converted into liquid fuels compatible with the current transportation infrastructure. Achieving cost-effective and environmentally sustainable production of plant-derived biofuels will, however, require advances in our understanding of plant biology, as well as genetic improvements of the plants themselves.
Traits desirable for biofuel crops have largely not been the targets of human selection. Domestication, for example, led to cereal grains which are large and easy to harvest. In contrast to the historic focus on seeds, breeders of future bioenergy crops seek to produce an abundance of vegetative biomass. This biomass – essentially the cell walls of the plants – should also be readily convertible into fuel and other high-value chemicals. The cell wall characteristics most critical for conversion have yet to be defined, but they likely involve the type, amount, and interactions of major cell-wall components, including cellulose, hemicellulose plus other matrix polysaccharides, and lignin.
Research in our lab centers on achieving a clearer understanding of bioenergy-relevant traits, including cell wall composition, structure, and dynamics. To elucidate the genes controlling these traits, we use the model plant Brachypodium distachyon. Related to wheat and native to the Mediterranean region, Brachypodium is a small, annual grass with a compact, sequenced genome and abundant genetic resources. Brachypodium also exhibits tremendousnatural variation in traits important for bioenergy. To mine this diversity, we are performing extensive phenotyping, including a microbial, simultaneous saccharification and fermentation assay to test how well plant material is converted to ethanol and other products. We are combining these data with an emerging wealth of genome sequence information to map the genetic loci underlying the phenotypic diversity. By elucidating biomass quantity and quality traits in a model grass, we aim to contribute to the knowledge base necessary to improve plants for sustainable bioenergy production.
Tyler, L., Bragg, J.N., Wu, J., Yang, X., Tuskan, G., and Vogel, J.P. (2010) Annotation and comparative analysis of the glycoside hydrolase genes in Brachypodium distachyon. BMC Genomics. 11:600 [PubMed]
International Brachypodium Initiative (2010) Genome sequencing and analysis of the model grass Brachypodium distachyon. Nature. 463, 763-768. [PubMed]