Molecular Perspective to Understand the Phenomenon of Self-Incompatibility and Its Utilisation in Crop Plants

Self-incompatibility (SI) is a genetically controlled mechanism for rejection of own pollen. It has been a favourite topic for botanists and geneticists since Darwin, who first discussed this phenomenon and suggested its central significance during the evolution of flowering plants. Different genetic and mechanistic systems of SI among different plant families suggest either multiple origins of SI or considerable evolutionary diversification. Within the last two decades, molecular and biochemical analyses have significantly contributed to the elucidation of the complex series of interactions occurring at the pollen–stigma interface. Molecular analyses of SI systems have focused on identifying and characterising the pollen and pistil components of the self-incompatible response as well as other proteins and events that lead to pollen rejection. In this review, an attempt has been made to provide a comprehensive insight for the molecular dissection of this important mechanism for its utilisation in crop improvement.