Rice diterpenoid phytoalexins: from biosynthesis and regulation to applications

Rice ( Oryza sativa ) diterpenoid phytoalexins play key roles in plant defense and ecological adaptation, and hold strong application potential. This review summarizes their biosynthesis, regulation, and functional diversification. We first outline the plastidial methylerythritol phosphate (MEP) pathway for isoprenoid precursor supply, the class II and class I diterpene synthases that catalyze the formation of diverse scaffold intermediates, and the subsequent insertion of oxygen by cytochromes P450, as well as further oxidation, which enhances structural complexity. We then discuss the multilayered regulatory networks that control diterpenoid phytoalexin accumulation under biotic and abiotic stress, as well as in allelopathic interactions. Further, the major application areas assessed include environmentally compatible agrochemicals and health‑related bioactive compounds. Finally, the highly modular and integrated architecture of rice diterpenoid metabolism will enable future efforts combining metabolic engineering, synthetic biology, and molecular breeding to achieve scalable production, rational redesign and the development of elite cultivars for sustainable agriculture and health‑related applications.