Male and female synchrony and the regulation of mating in flowering plants.

Successful mating clearly requires synchronous development of the male and female sexual organs. Evidence is accumulating that this synchrony of development also persists after pollination, with both pollen and pistil following complex, but highly integrated developmental pathways. The timing of the male-female interaction is crucial for the pistil, which, far from being a mature passive structure, is engaged in a continuing programme of development: only being receptive to the advances of the pollen for a relatively short window of time. This developmental programme is most conspicuous in the ovary, and this review focuses on the interaction between the male and female tissues in this structure. The review first considers pollen tube development in the ovary, concentrating of the mechanisms by which its growth is modulated at various control points associated with structures within the ovary. Second, alterations to this 'normal' developmental programme are reviewed and considered in the context of a breakdown of developmental synchrony. Finally, the consequences of male-female developmental synchrony and asynchrony are explored. Clearly, a synchronous male-female relationship leads to a successful fertilization. However, lack of synchrony also occurs, and could emerge as a powerful tool to investigate the regulation of mating.