Self-incompatibility in flowering plants

During the course of evolution, recognition mechanisms that prevent self-fe rtilization. in flowering plants have been selected. These mechanisms, name d self-incompatibility, allow self-pollen rejection by the pistil. In most cases, the self-incompatibility response is under die genetic control of a single multiallelic locus, the S (Self-incompatibility) locus. Depending on the genetic control of the self-pollen rejection, two major classes of sel f-incompatibility systems have been described. The most common systems corr espond to the gametophytic self-incompatibility, which has been well charac terized in the Solanacene and in the Papaveraceae. The second type of self- incompatibility systems corresponds to the sporophytic self-incompatibility , particularly well studied in the Brassicaceae. In the review article, we present recent advances in understanding the molecular events that lead to pollen recognition and rejection in both systems. Interestingly, different molecules and signaling pathways of a have been recruited during evolution of flowering plants to answer the same biological question: how to discrimi nate male partners and to efficiently prevent self-fertilization by the pis til of hermaphroditic flowers ? The origin and molecular evolution of these multiallelic systems is discussed.