Resistance to the SDHI Fungicide Pydiflumetofen in : Risk Assessment and Resistance-Related Point Mutation in Gene.

Peanut root rot (PRR) is a prevalent and destructive plant disease attributed to . Pydiflumetofen (Pyd) is a succinate dehydrogenase inhibitor (SDHI) with antifungal activity against , yet its resistance mechanism has been inadequately explored. In this study, the EC values for Pyd against 93 strains ranged from 0.0095 to 0.3815 μg/mL, with all strains displaying a minimal inhibitory concentration (MIC) of ≤1 μg/mL. Four Pyd-resistant (PR) mutants were obtained, exhibiting stable resistance levels and comparable fitness to their parental strains in terms of mycelia growth, hyphal tip morphology, asexual reproduction, and virulence assessment. Five-point mutations, including , , , , and , were identified in the PR mutants. However, molecular docking analysis indicated that only and could influence the sensitivity of to Pyd. These findings help evaluate 's resistance to Pyd and guide future PRR management with this fungicide.