PLANT EMBRYOGENESIS

The subject of this review is the development of the plant embryo. Pla nt embryogenesis is a unique process in the sense that it can be start ed not only from the fertilized egg but can also be initiated from oth er cells of the reproductive apparatus and even from somatic cells. On e of the challenges of this field is therefore to unravel the molecula r mechanisms that lead to the formation of a cell destined to form an embryo. A second important area of research is to determine the molecu lar basis of pattern formation in the embryo, a process that results i n a stereotyped organization of a seedling. On the one hand, the patte rn formation process has to establish precisely arranged tissue organi zation, but on the other hand sufficient flexibility during plant deve lopment has to be maintained to allow continuous formation of new orga ns from meristems.In this review we summarize recent work that employs a variety of experimental systems that range from genetic dissection of pattern formation in the zygotic embryo, androgenesis and in vitro fertilization to somatic embryogenesis. While each of these systems hi ghlights a different aspect of embryogenesis, they can be mutually ben eficial in helping to understand the making of the plant embryo.