Investigation of Antifungal Activity and Assessment of Resistance Risk of Fungicide Benzovindiflupyr in Pyricularia oryzae

Rice blast is a destructive disease caused by Pyricularia oryzae, which threatens global staple food production. This study aims to investigate antifungal activity and assess the resistance risk of benzovindiflupyr in P. oryzae. The mean EC50 value of benzovindiflupyr against 102 P. oryzae strains was 0.0395 μg/mL. After benzovindiflupyr treatment, mycelia and conidia became abnormal. The effectiveness of benzovindiflupyr was markedly greater compared to the commonly used fungicides pydiflumetofen, fenoxanil, and difenoconazole at the same concentration. Eleven benzovindiflupyr-resistant mutants were obtained with a resistance frequency of 9 × 10-4 through fungicide generation. In addition, these mutants showed a fitness penalty and cross-resistance with other succinate dehydrogenase inhibitor fungicides, such as fluxapyroxad and penflufen. Point mutations H245Y/D/L and N203H in PoSdhB, S77N in PoSdhC, and D122N/G in PoSdhD were identified in benzovindiflupyr-resistant mutants, which was confirmed by molecular docking. These results suggested a moderate resistance risk associated with benzovindiflupyr in P. oryzae.