Regulation of cell wall synthesis and assembly in grasses

The composition and cross-linking of cell wall polymers determines the efficiency by which biomass can be processed to release the abundant cell wall sugars for biofuel production. A better understanding of the cell wall structure is therefore essential to optimise the energy-potential of grasses and to enable the engineering and breeding of varieties in which cell-wall composition and cross-linking is optimized for conversion. It is estimated that more than a thousand genes are involved in the synthesis and remodelling of cell walls, but only a handful of genes have been characterised. Despite the considerable interest in developing grasses as a renewable energy source, the discovery of genes involved in cell wall biogenesis in these monocots is particularly poor. To optimize the amount, composition, and structure of cell walls in grasses we are identifying some of the genes involved. Due to the available genetic tools, its close phylogenetic relationship with energy grasses including Miscanthus, and C4 photosynthesis, maize is an ideal model for the discovery of cell wall related genes and the translation of gene-function discovery to more genetically recalcitrant bioenergy crops such as Miscanthus. Differential gene expression profiles have been determined by comparing elongating and non-elongating maize internodes using maize microarrays. Key candidate genes predicted to fulfil crucial roles in cell wall biosynthesis and remodelling will be targeted for functional testing in models with the aim that results be translated into Miscanthus. New tools including the production of antibodies that specifically recognise ferulic acid dimers are also being developed (in collaboration with Prof. Paul Knox, University of Leeds and Prof. John Ralph, University of Wisconsin-Madison) as these can be used to study the temporal and spatial aspects of cell wall cross-linking mediated by ferulic acid dimers.