Benzovindiflupyr is a novel succinate dehydrogenase inhibitor fungicide effective against many plant pathogens. However, the resistance risk of Didymella bryoniae to this fungicide is unknown. This study determined the baseline sensitivity of 69 wild D. bryoniae strains to benzovindiflupyr on mycelial growth with half-maximal effective concentrations (EC₅₀) of 0.0021–0.0983 μg/mL with an average of 0.027 ± 0.0216 μg/mL. The minimum inhibitory concentration was 3 μg/mL. Four benzovindiflupyr-resistant mutants were obtained by fungicide taming and their resistance could stably inherited. Most mutants were not strikingly different from wild-type strains in mycelial growth, dry weight, pathogenicity, and sensitivity to various environmental stress factors. Most benzovindiflupyr-resistant mutants showed positive cross-resistance to pydiflumetofen, fluopyram, fluxapyroxad, fluindapyr, pyraziflumid, isopyrazam, and boscalid, but not tebuconazole and fluazinam. Consequently, the resistance risk of D. bryoniae to benzovindiflupyr would be medium to high. A point mutation at codon 277 in SdhB, changing CAC (histidine) to TAC (tyrosine), was identified in highly-resistant mutant XN51BR-1 but not in other mutants. However, a point mutation at codon 248 in SdhB of Fusarium graminearum (equivalent to the H277Y change in D. bryoniae) conferred medium resistance to benzovindiflupyr. These results provide further information about the resistance risk and resistance mechanism of D. bryoniae to benzovindiflupyr.

Benzovindiflupyr 是一种新型琥珀酸脱氢酶抑制剂杀菌剂，对许多植物病原体有效。然而， Didymella broniae对这种杀菌剂的抗药性风险尚不清楚。本研究确定了 69 种野生D. bryoniae菌株对苯并氟嘧啶菌丝体生长的基线敏感性，半数最大有效浓度 (EC ₅₀ ) 为 0.0021–0.0983 μg/mL，平均值为 0.027 ± 0.0216 μg/mL。最低抑菌浓度为3微克/毫升。通过杀菌剂驯化获得了4个苯并烯氟嘧啶抗性突变体，其抗性可稳定遗传。大多数突变体在菌丝体生长、干重、致病性方面与野生型菌株没有显着差异，以及对各种环境压力因素的敏感性。大多数 benzovindiflupyr 抗性突变体对 pydiflumetofen、fluopyram、fluxapyroxad、fluindapyr、pyraziflumid、isopyrazam 和啶酰菌胺显示出阳性交叉抗性，但对戊唑醇和氟啶胺没有。因此， D. bryoniae对 benzovindiflupyr的抗药性风险为中到高。SdhB密码子 277 处的点突变，将 CAC（组氨酸）变为 TAC（酪氨酸），在高抗性突变体 XN51BR-1 中被鉴定，但在其他突变体中未被鉴定。然而，禾谷镰刀菌SdhB密码子 248 处的点突变（相当于D. broniae中的 H277Y 变化）) 赋予对 benzovindiflupyr 的介质抗性。这些结果提供了关于D. broniae对 benzovindiflupyr的抗性风险和抗性机制的进一步信息。