Asp-2078-Gly mutation confers ACCase-inhibiting herbicide resistance in Leptochloa chinensis (L.) Nees

BACKGROUND Chinese sprangletop ( Leptochloa chinensis (L.) Nees), a dominant weed species in Chinese rice fields, poses a significant threat to rice yield and quality because of its increasing resistance to herbicides. In particular, resistance to cyhalofop-butyl (Cyb) has become a major concern in weed control. The mechanism by which the Asp-2078-Gly mutation confers resistance to acetyl-CoA carboxylase (ACCase) inhibitors in L . chinensis remains unclear. In this study, we collected Cyb-resistant L . chinensis populations from rice-growing regions and characterized their resistance mechanisms. RESULTS Through molecular analysis, we identified a resistant population harboring the Asp-2078-Gly mutation. Whole-plant dose–response experiments showed that the resistant (R) population exhibited varying levels of resistance compared with the susceptible (S) population: resistance indices values were 15.42 for FOP herbicides Cyb, 12.77 for metamifop, 11.50 for fenoxaprop-P-ethyl; 13.13 for the DIM herbicide clethodim; and 8.61 for the DEN herbicide pinoxaden. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed no significant difference in ACCase gene expression between the Asp-2078-Gly mutant and the susceptible (S) population, indicating that resistance to Cyb was not due to target enzyme overexpression. Furthermore, the resistance of the mutant was not alleviated by P450 or glutathione S -transferase inhibitors, suggesting non-metabolic mechanisms. CONCLUSION Structural analysis confirmed that the Asp-2078-Gly mutation induces significant conformational changes in the herbicide-binding pocket, which reduces herbicide sensitivity and confers resistance. This study elucidates the resistance mechanism conferred by the Asp-2078-Gly mutation in L . chinensis , providing valuable insights for managing herbicide-resistant weeds. © 2026 Society of Chemical Industry.