Strigolactones: Biosynthesis, transport, perception, and signal transduction

Strigolactones (SLs) are carotenoid-derived phytohormones that regulate plant development and mediate rhizosphere interactions. Synthesized from β-carotene through a multistep enzymatic pathway, SLs modulate key physiological processes, including shoot branching, leaf development, flowering, and root growth. In addition to performing endogenous hormonal roles, SLs are exuded into the soil, where they serve as ecological signals. Exuded SLs facilitate symbiotic relationships with arbuscular mycorrhizal fungi to enable nutrient exchange and are also exploited by parasitic weeds to locate host plants. Although the core SL biosynthesis and signaling pathways have been extensively characterized, research continues to uncover new layers of complexity in their regulation and function. Here, we present a comprehensive overview of SLs, summarizing the past major achievements and recent advances in their biosynthesis, transport, perception, and signal transduction, together with their multifaceted functions. We discuss current challenges in SL research and highlight important questions for future investigations. Addressing these issues can further enhance our understanding of the SL pathway and promote its application in agriculture.