Abstract Botrytis cinerea causes Botrytis blossom, shoot and fruit blight in pistachio and gray mold in grape. The hydroxyanilide (Hyd) fenhexamid, one of the most frequently used fungicides for Botrytis control, inhibits the 3-ketoreductase (Erg27) of the ergosterol biosynthesis pathway. Due to its site-specific mode of action, this fungicide is at-risk for resistance development. In this study, 74 and 58 B. cinerea isolates, collected from Californian pistachio orchards and grape vineyards, respectively, were evaluated for their in vitro sensitivity toward fenhexamid. Of the 58 grape isolates, 90% were sensitive to fenhexamid (HydS, EC50 50 μg/ml) phenotypes toward fenhexamid, respectively. The 3-ketoreductase erg27 gene was sequenced from all the 29 B. cinerea fenhexamid-resistant phenotypes (HydLR, WR, MR, HR) detected in this study. The resulting sequences were then compared to corresponding sequences obtained from 21 fenhexamid-sensitive isolates (HydS). Of the 6 HydLR phenotype from grape, 3 had a substitution of proline to serine at position 238 (P238S). No mutations were found in the remaining 3 HydLR nor in the 10 HydLR pistachio isolates. The only HydWR phenotype from pistachio presented a change at position 309 resulting the replacement of valine to Methionine (V309M). Among the HydMR phenotype from pistachio, two had F412S alteration while the other two possessed the L400F alteration at position 400. Highly resistant isolates (HydHR) carried a substitution of the phenylalanine at position 412, either serine (F412S) or isoleucine (F412I). Inoculations on detached grape berries showed that field rates of Elevate® 50 WDG (fenhexamid) controlled HydS and HydLR, but not the HydMR and HydHR phenotypes. The presence of B. cinerea fenhexamid-resistant phenotypes in pistachio and grape fields in California must be monitored continually and resistance management practices implemented as needed for sustained Botrytis blossom, shoot and fruit blight and gray mold controls with Elevate® 50 WDG.

中文翻译：

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从加利福尼亚开心果园和葡萄葡萄园收集的灰葡萄孢菌对芬六胺抗性的表型和分子特征

摘要 Botrytis cinerea 引起开心果中的灰霉病、枝条和果枯病以及葡萄中的灰霉病。羟基苯胺 (Hyd) fenhexamid 是最常用于控制灰霉病的杀菌剂之一，可抑制麦角甾醇生物合成途径的 3-酮还原酶 (Erg27)。由于其特定部位的作用方式，这种杀菌剂有产生抗药性的风险。在这项研究中，分别从加利福尼亚开心果园和葡萄葡萄园收集了 74 和 58 株灰霉病菌，评估了它们对芬六胺的体外敏感性。在 58 个葡萄分离株中，90% 分别对 fenhexamid (HydS, EC50 50 μg/ml) 表型对 fenhexamid 敏感。3-酮还原酶 erg27 基因是从本研究中检测到的所有 29 种 B. cinerea fenhexamid 抗性表型（HydLR、WR、MR、HR）中测序的。然后将得到的序列与从 21 个对芬六胺敏感的分离株 (HydS) 中获得的相应序列进行比较。在来自葡萄的 6 个 HydLR 表型中，3 个在位置 238 (P238S) 处将脯氨酸替换为丝氨酸。在剩余的 3 个 HydLR 和 10 个 HydLR 开心果分离物中均未发现突变。来自开心果的唯一 HydWR 表型在 309 位发生了变化，导致缬氨酸替换为甲硫氨酸 (V309M)。在来自开心果的 HydMR 表型中，两个具有 F412S 改变，而另外两个在 400 位具有 L400F 改变。高抗性分离株 (HydHR) 在 412 位进行苯丙氨酸取代，丝氨酸 (F412S) 或异亮氨酸 (F412I)。对分离的葡萄浆果进行接种表明，Elevate® 50 WDG (fenhexamid) 的田间施用率控制了 HydS 和 HydLR，但不是 HydMR 和 HydHR 表型。必须持续监测加利福尼亚州开心果和葡萄田中 B. cinerea fenhexamid 抗性表型的存在，并根据需要实施抗性管理实践，以使用 Elevate® 50 WDG 持续控制灰霉病开花、枝条和果枯病以及灰霉病。