Female Gametophyte Development in Higher Plants - Meiosis and Mitosis Break the Cellular Barrier

Meiotic products in higher plants should undergo a determined number of mitotic cycles before differentiating gametes. This creates a unique meiosis-mitosis interface, traverse of which is an absolute requirement for gametophyte development. In the absence of cytokinesis during megasporogenesis - as seen in the bisporic and tetrasporic types - the haploid nuclei produced by meiosis are driven to undergo mitotic cycles within the same cell. Similarly, the last of the mitotic cycles leads to a unique type of cell wall formation resulting in cellularization of the coenocytic female gametophyte, creating a mitosis-cellularization interface. Cell cycle regulation in terms of the molecules that interface with these two key spatio-temporal developmental settings should be of interest to both cell and developmental biologists. High throughput techniques of functional genomics are required for both interpretation of female gametophyte evolution and success of the biotechnological initiatives of transferring apomixis-related genes to crop plants.