Black shank, a devastating disease in tobacco production worldwide, is caused by the oomycete plant pathogen . Fluopicolide is a pyridinylmethyl-benzamides fungicide with a unique mechanism of action and has been widely used for controlling a variety of oomycetes such as , , and . However, the fluopicolide-resistance risk and molecular basis in have not been reported. In this study, the sensitivity profile of 141 strains to fluopicolide was determined, with a mean median effective concentration (EC) value of 0.12 ± 0.06μg/mL. Five stable fluopicolide-resistant mutants of were obtained by fungicide adaptation, and the compound fitness index of these resistant mutants were lower than that of their parental isolates. Additionally, cross-resistance tests indicated that the sensitivity of fluopicolide did not correlate with other oomycete fungicides, apart from fluopimomide. DNA sequencing revealed two point mutations, G765E and N769Y, in the PpVHA-a protein in the fluopicolide-resistant mutants. Transformation and expression of genes carrying G765E and N769Y in the sensitive wild-type isolate confirmed that it was responsible for fluopicolide resistance. These results suggest that has a low to medium resistance risk to fluopicolide in laboratory and that point mutations, G765E and N769Y, in PpVHA-a are associated with the observed fluopicolide resistance.

中文翻译：

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烟草黑胫病病原菌烟草疫霉抗氟吡菌胺突变体的特征

黑胫病是全世界烟草生产中的一种毁灭性疾病，由卵菌植物病原体引起。 Fluopicolide是一种吡啶基甲基苯甲酰胺类杀菌剂，具有独特的作用机制，已广泛用于防治多种卵菌，如、、、、等。然而，氟吡菌胺耐药风险和分子基础尚未报道。本研究测定了141株菌株对氟吡菌胺的敏感性，平均中位有效浓度（EC）值为0.12±0.06μg/mL。通过杀菌剂适应，获得了5个稳定的氟吡菌胺抗性突变体，这些抗性突变体的复合适应度指数低于其亲本分离株。此外，交叉耐药性测试表明，除氟吡菌胺外，氟吡菌胺的敏感性与其他卵菌杀菌剂不相关。 DNA 测序显示氟吡菌胺抗性突变体的 PpVHA-a 蛋白中有两个点突变，G765E 和 N769Y。携带 G765E 和 N769Y 的基因在敏感野生型分离株中的转化和表达证实，它与氟吡菌胺耐药性有关。这些结果表明，实验室对氟吡菌胺具有低至中度耐药风险，并且 PpVHA-a 中的点突变 G765E 和 N769Y 与观察到的氟吡菌胺耐药性相关。