CELL FATE AND CELL-DIFFERENTIATION STATUS IN THE ARABIDOPSIS ROOT

Post-embryonic development in plants is mainly achieved by its meriste ms. Within the Arabidopsis root meristem, both the fate and origin of its cells can be predicted with high accuracy. Mutants defective in th e determination of root cell fates show that the corresponding genes a re first required during embryogenesis. The sub-specification of cell fates, such as during epidermal root hair formation, involves transcri ption factors and phytohormones. In the Arabidopsis root, initial cell fate specification events must be followed by position-dependent rein forcement of cellular identity. A major question remains as to whether the signals that are involved in initiating the cellular pattern are the same or different from the signals used to reinforce it. The integ rity of the root meristem is kept by balancing cell proliferation and cell differentiation, and differentiation-inhibiting signals originati ng from the quiescent centre are involved.