Aim: Our research is devoted to the mechanisms that control cell elongation in seed plants and especially in roots. Given the role of roots in exploration of soil substrate, anchorage and uptake of nutrients, the expansion of root cells is necessary to develop a functional root system.
The identification of certain actors in the process of cell elongation and its control is the aim of the present research proposal. It fits in the research themes of the lab that focus on different aspects of the cytoskeleton and the cell wall in relation to cell elongation (De Cnodder et aI., 2005; Kerstens en Verbelen, 2003; Le et aI., 2004; Verbelen et aI., 2005). Promotor and co-promotor have gained substantial experience in microscopy, root development and molecular biological techniques to supervise this research proposal.The body of higher plants consists of cells that are formed in meristems. Outside the meristems, these newly formed cells generally expand considerably before reaching a stage of differentiation and maturation. The development of the Arabidopsis thaliana root epidermis is well described at the meristem level, including the quiescent center and the founder cells that give rise to the epidermal cell files in the root (Benfey and Scheres, 2000; Dolan et aI., 1993; van den Berg et aI., 1998). The Arabidopsis root is useful for the study of cell elongation. It is small, exhibits a highly predictable developmental pattern and can be easily visualized (with a normal microscope). The cells that are formed in the meristem can be easily traced when they pass through the elongation zone to reach the differentiation zone. Fast elongation of these cells occurs in the zone 400-9001lm away from the root tip. In each trichoblast cell file of the epidermis a new cell enters the elongation zone every 30 min and elongates from 35 to 150llm in about 3 hours (Le et aI., 2001). Such a fast growth needs accurate control mechanisms of the cell's physiology. The cell wall needs to be loosened to permit the anisotropic growth, e.g. by the action of xyloglucan endotransglucosylase/hydrolases (XTHs, Vissenberg et aI., 2000, 2003, 2005a, 2005b) but at the same time, needs to remain strong enough to prevent lysis of the cell.
Obiectives: We will identify regulatory genes that are activated at the start, the middle or the end of cell elongation depending on the transgenic line.