XVI International Botanical Congess

Postembryonic shoot development in higher plants is marked by repetitive organ formation via a self-perpetuating stem cell system, the shoot meristem. The destiny of each stem cells daughter cell is determined by its position within the shoot meristem: cells in the center remain pluripotent stem cells, whereas cells at the periphery form organs and undergo differentiation. Genetic and molecular analysis suggest that specification of stem cell fate requires signaling from underlying cells (Moussian et al. 1998, Mayer et al. 1998). These cells are established early in embryogenesis, before the actual stem cells and by a series of asymmetric divisions become confined to the prospective shoot meristem. Recent observations suggest that mechanistic principles of stem cell regulation are shared not only between shoot and root meristems, but also between animal stem cell system and plant meristems. Moussian et al. 1998, EMBO 17, 799-1809, Mayer et al., 1998 Cell 95, 805-815