Cyprosulfamide alleviates nicosulfuron injury in maize through ZmCYP81Q32/ZmGSTL2-mediated detoxification and...

Herbicide safeners can induce herbicide tolerance in crops, yet the underlying molecular mechanism remains poorly understood. In this study, we systematically investigated the mechanism by which the safener cyprosulfamide (CSA) alleviates nicosulfuron (Nsf) phytotoxicity in maize through integrated physiological, biochemical, multi-omics, and functional validation approaches. CSA significantly mitigated Nsf-induced growth inhibition, restoring physiological homeostasis by preserving photosystem II efficiency and photosynthetic pigment contents while tightly suppressing reactive oxygen species (ROS) accumulation. Integrated transcriptomic and metabolomic analyses revealed that CSA orchestrates a specific defensive reprogramming: it broadly activates the canonical Phase I-III metabolic detoxification system and simultaneously induces flavonoid biosynthesis and coordinated accumulation. Among the representative CSA-responsive detoxification genes, the endoplasmic reticulum-localized cytochrome P450 ZmCYP81Q32 was shown to bind Nsf. Heterologous expression of ZmCYP81Q32 in yeast conferred tolerance to multiple herbicides, including sulfonylureas, triazines, and triketones. In addition, GST family members, represented by ZmGSTL2, enhanced herbicide tolerance in heterologous assays. In Arabidopsis, overexpression of ZmCYP81Q32 enhanced Nsf tolerance, and LC-MS/MS analysis provided supporting evidence for its potential involvement in Nsf hydroxylation. Collectively, our findings support a dual-defence model in which CSA alleviates Nsf injury through enhanced metabolic detoxification and flavonoid-associated responses that may contribute to reduced oxidative injury. These results provide candidate detoxification genes and a mechanistic framework for future improvement of herbicide tolerance in crops.