The plant cell wall is important in human nutrition and health as well as forming the raw material for a variety of economic processes such as pulp and paper manufacture, as a construction material in the form of wood and in the production of textiles. Additionally, polysaccharides extracted from cell walls form the basis for a variety of gels, thickeners and adhesives. Increasingly the plant cell wall is being viewed as an important source of biomass for energy production in order to reduce the dependence on non-renewable fossil based fuels. A detailed understanding of processes controlling plant cell wall formation is thus vital in order to improve the potential for biomass production as well as to develop more environmentally friendly processing methods and tailor-made products for specific applications. Despite the undoubted importance of the cell wall both from the perspective of plant development as well as from a human viewpoint, relatively little is current understood about its biosynthesis.
A high proportion of the plant genome is dedicated to the synthesis and breakdown of the cell wall components. An analysis of the Arabidopsis genome has predicted that over 700 genes (around 2.5% of the total genome) encode carbohydrate-active enzyme classes of glycoside hydrolases and glycosyltransferases (www.cazy.org). We have utilised both Arabidopsis thaliana and hybrid aspen (poplar) model systems to identify and characterise key genes involved in primary and secondary cell wall biosynthesis. Transcript profiling of the poplar wood forming tissues has identified a number of genes which are upregulated in the zone of cell division and elongation (Hertzberg et al., 2001) and these genes represent candidates to be involved in primary cell wall formation.
Comparative bioinformatics has been used to identify Arabidopsis homologs of a number of these upregulated Poplar transcripts and knockouts obtained using a reverse genetics approach. Several of these mutants display a visible phenotype and work has been undertaken to characterise them and to understand the role that they may play in the synthesis of the cell wall (Singh et al., 2005). The same approach has been used to identify genes upregulated in the zone of secondary cell wall formation (Ubeda-Tomas et al., 2007). A major focus of the lab recently has been to study the function of a group of glycosyltransferases which appear to function to synthesise the hemicellulose glucuronoxylan (GX), a major component of the secondary cell wall (Wu et al., 2009). This has shown that at least 4 of the GX synthesis enzymes have closely related functional homologs providing insight into a potentially complex regulation of their activity. This work is providing valuable new information about the control of secondary growth in plants which will help in improving cell walls as a useful biomaterial for a variety of applications.
Przemyslaw Ociepa. The Role of Pectin Methylesterase enzymes in Plant Development. Funding from Interreg IV, Kerkut Trust and Biological Sciences.
Affiliate research group(s)
Institute for Life Sciences (IfLS)
We are using a transactivation based approach to alter the adundance of key sugars required for RGII synthesis in different tissues of Arabidopsis.
The IRX10, IRX10-Like, IRX14 and IRX14-Like glycosyltransferases are required for GX backbone synthesis
Identifying the functions of rhamnogalacturonan II during root development using an inducible RNAi-based gene knockdown approach in Arabidopsis thaliana.
Improving understanding of the uptake of phosphate by plants from soils by imaging root systems using X-Ray Computed Tomography.
Dr Alan Marchant
Faculty of Natural & Environmental Sciences
Life Sciences Building 85
University of Southampton
Telephone:(023) 8059 4363