My research involves two core initiatives that relate to the structure and function of plant cell walls and their fundamental importance as sources of food, feed, fiber and bioenergy. The first involves a long term project to characterize the protein population, or proteome, of the plant cell wall and to study the expression and function of wall-localized proteins during plant growth and development, and following pathogen challenge. We are identifying specific proteins that contribute to plant cell-wall assembly and breakdown in softening fruits, or that are associated with disease resistance. The second major research theme is based on the central role that the hemicellulose-cellulose matrix of grass cell walls plays as a major source of carbon to the biofuel (bioethanol) industry. Demand for research in this area is increasing dramatically, given current concerns regarding energy security and global climate change.

An improved understanding of the mechanisms of plant cell wall during fruit development, ripening, and disease resistance will address important commercial and agricultural objectives: namely, major improvements in food quality and post-harvest handling, storage, and processing. These objectives may be achieved by devising strategies to enhance the longevity of fruit through controlling cell-wall degradation and thereby slow the rate of fruit softening. Success in developing such an approach would afford growers more flexibility with regard to harvesting regimes, since an extended shelf-life would provide the option of extending the ripening time of the fruit on the vine. This would have profound implications in terms of elevating the nutritional status of the crops. The impact of the proposed research is extremely broad and should extend from providing individual consumers with consistently high quality crops to enhancing profitability for growers. We are also currently characterizing new families of wall-associated proteins and gaining a better understanding of plant wall dynamics in order to generate plants with enhanced potential as bioenergy crops. Lastly, we are developing strategies to survey broad ranges of grass species, and to examine grass diversity, with the ultimate goal of identifying a portfolio of feedstocks for optimal carbon sequestration and biomass production, while prioritizing the development of long term sustainable cropping systems.

Three basic approaches are being undertaken to catalog plant cell-wall proteins. The first involves identifying wall proteins following mass spectrometry and isotopic labeling. We have developed a protocol to identify multiple classes of new tomato-fruit wall-associated proteins. A second approach involves computational prediction of the theoretical wall proteome following database mining. Lastly, we are using functional screens to identify proteins secreted from several plant species. We have now identified a substantial number of new, unanticipated wall-localized proteins from fruits, leaves, and floral organs that show specific developmentally regulated expression patterns.
We are also conducting targeted analyses of specific families of wall-modifying proteins. In particular, we are paying close attention to the characterization of proteins that modify the cellulose-xyloglucan matrix. We have identified a new class of plant cellulases that have a cellulose-binding domain (CBD) and demonstrated the cellulose affinity and substrate specificity of these proteins. New data suggest that they influence the structure or organization of the cellulose-hemicellulose matrix of plant walls. We have also established a cell wall profiling pipeline, whereby collaborations with plant breeders allow large numbers of samples from diverse field-grown potential bioenergy feedstocks are screened (medium to high throughput) for quality traits and ethanol yield potential.

The establishment of a cell wall profiling facility, through funding from CALS, the New York Farm Viability Institute and the NE Sun Grant Initiative has had an enabling effect on activities in the NE region related to biofuels and the development of bioenergy feedstocks. We recently founded the Cornell Sustainable Bioenergy Initiative (CSBI) and our wall analysis unit, which operates through this initiative, and has received in only the first few months of operation a number of requests for letters of support and information from the academic and industrial sectors. The facility will provide important data on defining the potential of various feedstocks in New York and other states in the region. We anticipate that this trend will continue and that the CSBI will have an important role in the development of an upstate agroenergy economy.