Molecular mechanisms and genetic regulation of self-incompatibility in flowering plants: implications for crop improvement and evolutionary biology.

Self-incompatibility is a fundamental biological mechanism in flowering plants that prevents self-fertilization, thereby promoting outcrossing and enhancing genetic diversity. This complex system has independently evolved across multiple angiosperm lineages and is crucial in maintaining plant reproductive success. Recent research has expanded our understanding of self-incompatibility's molecular basis and uncovered key genes and signaling pathways involved in self-incompatibility responses, such as S-RNase in Solanaceae and PrsS-PrpS in Papaveraceae, as well as the SRK-SCR interaction in Brassicaceae. However, despite significant advances, many aspects of self-incompatibility, such as the interplay between gene duplications, polyploidization, and the evolution of novel self-incompatibility mechanisms, remain underexplored. This review integrates findings from various plant families, including Solanaceae, Rosaceae, Papaveraceae, and Brassicaceae, and discusses the evolutionary dynamics of self-incompatibility systems, highlighting the role of gene duplication, recombination, and translocation events in shaping self-incompatibility diversity. Special emphasis is placed on understanding how modern molecular techniques, such as CRISPR/Cas9 and marker-assisted selection, can be employed to transition self-incompatibility to self-compatibility in economically significant crops. Additionally, the role of epigenetic changes and modifier genes in mediating transitions from self-incompatibility to self-compatibility is addressed, offering insights into how these mechanisms can be leveraged for crop breeding and hybrid seed production. Future research should focus on elucidating the molecular mechanisms underlying self-incompatibility responses, exploring the potential of targeted gene editing to overcome reproductive barriers, and understanding the evolutionary resilience of self-incompatibility systems to environmental changes.