Lay summary
Lead:Cell and ultimately plant growth depend on the proper development of the cell wall that surrounds each cell. The composition of plant cell walls is relatively well understood. There is, however, little understanding on the mechanisms that regulate the spatial and temporal extent of cell wall growth. This project addresses the function of different components that appear to be involved in the regulation of this complex process.Background:Cell walls consist of the polysaccharides cellulose, hemicellulose, and pectin. In addition, a number of proteins are important for the mechanical properties of the cell wall or strongly influence its growth. In previous work, we have identified a class of LRR-extensin proteins that are located in the cell wall and appear to regulate wall growth. Arabidopsis thaliana plants lacking the LRX1 proteins are unable to properly develop cell walls.To better understand the function of LRX1, we identified mutant Arabidopsis plants that are able to overcome the defects induced by the lrx1 mutation. These plants, referred to as “suppressors of lrx1”, are possibly modified in an LRX1-related process and we are currently characterizing the function of those genes that are affected in these plants.In a parallel approach, we were able to show that flavonoids, a large group of secondary metabolites normally associated with responses of plants to biotic and abiotic stresses, also influence cell shape formation. Arabidopsis plants with a modified flavonoid accumulation develop deformed cells.Goal:The goal of this project is several-fold. We intend to better understand the regulation of cell wall formation. What components define the time-point and extent of cell growth and how are they executing their regulatory activity? To this end, we started characterizing the role of LRX1 in Arabidopsis. One potential regulatory mechanism that we have recently identified as being potentially important for this process is being analyzed in detail. Furthermore, we are elucidating the mode of action of flavonoids in the process of cell (wall) shape determination.Significance:Cell walls are highly complex structures. They serve a protective function for individual cells and whole plants, and recently became the centre of interest because of their source of carbohydrates for the production of fuel (biofuels). Even though the importance of cell walls is obvious, little is known about the contribution of individual components to the mechanical properties of the cell wall. Also, very limited information is available on the growth properties of this structure. Our research efforts aim at elucidating the function of a few components during cell wall formation and hence the mechanisms by which plants can sense and modify processes that take place in their extracellular matrix.