Induction of the embryogenic pathway in somatic plant cells

Differentiated somatic plant cells have the capability to reinitiate an entire ontogenic program called somatic embryogenesis. Reversible totipotency of somatic plant cells is a specific and scientifically exciting phenomenon which is based on the general flexibility of the developmental program of plants. Environmental and endogenous factors together determine the developmental fate of plants through the activation/inactivation of meristems. In vitro somatic embryogenesis provides an unique and usefull tool to reveal the physiological, cellular and molecular backgrounds of this developmental flexibility. Moreover, it can serve as a modell for zygotic embryogenesis in many aspects and finally it provides a possibility for mass propagation of individual plants with suitable characters. Scientific interest as well as application possibilities verify the detailed study of somatic embryogenesis in plants. Here we try to summarise the present knowledge on the early induction phase of embryogenic competence of somatic plant cells including some of our recent results using alfalfa as a modell system.