OsGSTU1 contributes to rice (Oryza sativa) tolerance to tripyrasulfone via metabolic detoxification

Direct-seeded rice (Oryza sativa) is increasingly adopted with agricultural mechanization, but weed competition, particularly from Echinochloa crus-galli, remains a major yield constraint. Tripyrasulfone, a novel HPPD-inhibiting herbicide, offers excellent selectivity for direct-seeded rice and effective control of resistant weeds; however, the molecular basis underlying rice tolerance to this herbicide is largely unknown. This study aimed to identify and functionally characterize the key gene(s) responsible for tripyrasulfone tolerance in rice.

Here, we identify and functionally characterize the tau-class glutathione S-transferase gene OsGSTU1, which contributes to tolerance to tripyrasulfone in rice. Phylogenetic analysis placed OsGSTU1 within the detoxification-related GSTU subfamily. Molecular docking revealed strong binding affinities of OsGSTU1 for tripyrasulfone (-6.9 kcal mol^-1) and its active metabolite hydrolyzed tripyrasulfone (HDT, -5.6 kcal mol^-1). Across diverse rice varieties, expression of OsGSTU1 correlated positively with herbicide tolerance, yet the coding sequences of tolerant and sensitive cultivars were identical, indicating that differential expression, not protein sequence variation, underlies phenotypic differences. Subcellular localization showed OsGSTU1 at both the nucleus and plasma membrane. Heterologous expression in Escherichia coli conferred enhanced tolerance to both compounds, and transgenic rice overexpressing OsGSTU1 exhibited significantly increased herbicide tolerance and accelerated tripyrasulfone metabolism, whereas knockout lines displayed heightened susceptibility.

This study suggests that OsGSTU1, a tau-class glutathione S-transferase, contributes to tolerance to the HPPD-inhibiting herbicide tripyrasulfone in rice via enhanced metabolic detoxification. This work suggests that OsGSTU1 may serve as a promising candidate gene associated with tripyrasulfone tolerance in rice and provides mechanistic insights into its potential role in herbicide detoxification, supporting the sustainable use of tripyrasulfone in direct-seeded rice systems and contributing to improved crop protection and herbicide resistance management. © 2026 Society of Chemical Industry.