SYSTEMS LEVEL ENGINEERING OF PLANT CELL WALL BIOSYNTHESIS

There has been an explosion of interest and optimism in the prospect of exploiting plant cell wall sugars to produce biofuel. Amenability to such a process is dependent upon overall cell wall composition and the manner in which those components interact. One mechanism regulating cell wall biosynthesis is the activity of transcription factors that control higher order events of growth and differentiation and the likely direct regulation of processive and non-processive glycosyltransferases as well as the phenylpropanoid metabolic grid. We seek systems level insight into regulatory networks affecting monocot and dicot growth and development and cell wall biosynthesis that will ultimately lead to a better understanding of bioenergy-related properties.

BRACHYPODIUM: A NEW MODEL SYSTEM FOR BIOFUEL GENOMICS

Brachypodium distachyon is part of the Pooidae subfamily, which includes temperate cereals and grasses.  Important to our interests, brachypodium is a model system for herbaceous plants that are candidates for biofuel crops such as switchgrass and Miscanthus. The cell walls of these grasses differ in composition from dicots, namely they have larger amount of arabinoxylan and a unique hemicellulose, mixed-linked glucan. Thus, brachypodium is a necessary research tool for feedstock related plant genomics.  We are part of the DOE-Joint Genome Institute project awards for deep EST and whole genome sequencing, and resequencing of brachypodium.

NATURAL GENETIC VARIATION IN BIOMASS YIELD AND CELL WALL PROPERTIES

Understanding the type of variation that is exploited by plant breeders, DNA sequence variation leading to changes in gene expression or amino acid sequence, for example, will provide more educated decisions on future crop improvement approaches.  The exploration of natural genetic variation can provide insight into how this might be done.  We have measured significant genetic variation for cell wall properties among arabidopsis and maize accessions.  This phenomenon provides an opportunity to resolve the cell wall metabolism apparatus by cloning QTLs, which will reveal the subtle manner in which genes can be modified to alter phenotype, i.e., slight modifications of protein function or gene regulation rather than complete loss-of-function or constitutive over-expression.  We are particularly interested in treating expression level of cell wall genes as a quantitative trait (eQTL).