Developmental control of cell division patterns in the shoot apex

The shoot apical meristem is a group of rapidly dividing cells that generat e all aerial parts of the plant. It is a highly organised structure, which can be divided into functionally distinct domains, characterised by specifi c proliferation rates of the individual cells. Genetic studies have enabled the identification of regulators of meristem function. These factors are i nvolved in the formation and maintenance of the meristem, as well as in the formation of the primordia. Somehow, they must also govern cell proliferat ion rates within the shoot apex. Possible links between meristem regulators and the cell cycle machinery will be discussed. In order to analyse the ro le of cell proliferation in development, cell cycle gene expression has bee n perturbed using transgenic approaches and mutation. The effect of these a lterations on growth and development at the shoot apex will be presented. T ogether, these studies give a first insight into the regulatory networks co ntrolling the cell cycle and into the significance of cell proliferation in plant development.