Boys and Girls Come Out to Play: The Molecular Biology of Dioecious Plants

The majority of the world's flowering plants are hermaphroditebut many of them encourage cross pollination by means of spatialor temporal separation of eggs and pollen, or by genetically-controlledphysiological incompatibility. A minority of species has takenthe avoidance of self-pollination to its logical conclusionby evolving two distinct and sexually different forms (dioecy).In a very small number of plants, dioecy has been accompaniedby the development of sex chromosomes. From the study of thedevelopment of male and female flowers of different speciesit is clear that there is no common underlying mechanism andthat sex determination systems leading to dioecy have originatedindependently many times in evolution. This Botanical Briefinghighlights new information from recent molecular approachesin the study of dioecy.Copyright 2000 Annals of Botany Company Review, sex determination, dioecy, sex chromosome