The phytopathogenic fungus Fusarium graminearum is the major causal agent of fusarium head blight (FHB), which is one of the most serious diseases in wheat. Based on our previous work, the 1,2,3-triazole phenylhydrazone scaffold was further optimized at three modification sites to improve its antifungal activity against F. graminearum. The optimization yielded compound 8d was discovered to be a potent fungicidal agent with an EC50 value of 0.28 μg/mL against F. graminearum, which is 3.6 times lower than previously reported. In addition, 8d also exhibited good inhibitory activities against Rhizoctonia solani and Sclerotinia sclerotiorum with EC50 values of 0.86 and 1.66 μg/mL, respectively. In vivo testing demonstrated that 8d could effectively suppress the disease development of FHB at 200 μg/mL with a protection efficacy of 80.6%. Scanning electron micrographs and transmission electron micrographs showed that the external morphology and internal contents of F. graminearum hyphae were abnormal after 24 h of 8d treatment. Therefore, compound 8d was a promising fungicide candidate for further development.

中文翻译：

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1,2,3-三唑苯腙作为潜在杀菌剂对抗禾谷镰刀菌的生物活性引导结构优化

植物病原真菌禾谷镰刀菌是小麦赤霉病（FHB）的主要病原体，该病是小麦中最严重的病害之一。基于我们之前的工作，1,2,3-三唑苯腙支架在三个修饰位点进一步优化，以提高其对禾谷镰刀菌的抗真菌活性。优化产生的化合物 8d 被发现是一种有效的杀真菌剂，对禾谷镰刀菌的 EC50 值为 0.28 μg/mL，比之前报道的低 3.6 倍。此外，8d 对立枯丝核菌和核盘菌也表现出良好的抑制活性，EC50 值分别为 0.86 和 1.66 μg/mL。体内试验表明，8d 浓度为 200 μg/mL 时可有效抑制 FHB 的疾病发展，保护效力达 80.6%。扫描电子显微照片和透射电子显微照片显示，处理8d 24 h后禾谷镰刀菌菌丝的外部形态和内部含量异常。因此，化合物 8d 是一种有前景的杀菌剂候选物，有待进一步开发。