Growth and Development of higher plants

Cell division is a determinative process during the growth and development of roots. Several physiological studies have demonstrated that plants possess mechanisms controlling the architecture of root systems in relation to internal and environmental conditions. Root growth has to keep pace with shoot growth and, if required, untouched areas of the soil have to be reached to maintain a prosperous growth. On the other hand, in unfavourable conditions, root growth might be slowed down and a shift towards the production of reserve tissues might represent an advantage. All of these developmental decisions finally are mediated by the growth centres of the root, being the apical meristems and the outer tissue layer of the stele, the pericycle. In these tissues the cell cycle can be promoted, delayed or switched off. Therefore cell cycle control is central to the dynamics of root architecture. This work package will be dedicated to three major aspects of cell cycle control during root development:
1. Cell division in apical meristems and root growth rate.
2. The exit from cell division and the switch from the mitotic cycle to the endocycle in the root.
3. The onset of cell division in the pericycle and the initiation of new lateral roots
During the last decade P1A, B, C have generated a valuable collection of mutants, transgenic lines, reporter constructs etc. that have become powerful tools to analyse cell division activity and lateral root formation in Arabidopsis. These lines and constructs will be instrumental to evaluate cell division activity in the root upon abiotic stress conditions (P3) and in hormonal perturbation experiments (P1D, EU1).