The molecular biology of self-incompatibility systems in flowering plants

Self-incompatibility is a common mechanism by which flowering plants can ex ert some control over the process of fertilization. Typically, the self-inc ompatibility response involves the recognition and rejection of self-incomp atible pollen which leads to a block in self-fertilization and, as a conseq uence, promotes outcrossing. In recent years, considerable progress has bee n made in the molecular understanding of several self-incompatibility syste ms. Interestingly, a common mechanism for self-incompatibility is not emplo yed by all flowering plants, but in fact quite diverse mechanisms have been recruited for the rejection of self-incompatible pollen. In this review, t he recent advances in the self-incompatibility systems of the Solanaceae, P apaveraceae, and Brassicaceae will be described as well as some of the mole cular work that is emerging for the Poaceae and the heteromorphic self-inco mpatibility systems.