Abstract：
The phytopathogenic oomycete Phytophthora litchii is the culprit behind the devastating disease known as \"litchi downy blight\", which causes large losses in litchi production. Although fluopimomide exhibits strong inhibitory efficacy against P. litchii, the exact mechanism of resistance is still unknown. The sensitivity of 137 P. litchii isolates to fluopimomide was assessed, and it was discovered that the median effective concentration (EC50) of the fungicide had a unimodal frequency distribution with a mean value of 0.763 ± 0.922 μg/mL. Comparing the resistant mutants to the equivalent parental isolates, the resistance mutants\' survival fitness was much lower. While there was no cross-resistance between fluopimomide and other oomycete inhibitors, there is a notable positive cross-resistance between fluopimomide and fluopicolide. According to the thorough investigation, P. litchii had a moderate chance of developing fluopimomide resistance. The point mutations N771S and K847N in the VHA-a of P. litchii (PlVHA-a) were present in the fluopimomide-resistant mutants, and the two point mutations in PlVHA-a conferring fluopimomide resistance were verified by site-directed mutagenesis in the sensitive P. capsici isolate BYA5 and molecular docking.
摘要：
植物病原卵菌李氏疫霉是被称为“荔枝枯萎病”的毁灭性疾病背后的罪魁祸首，这在荔枝生产中造成了巨大的损失。尽管氟哌胺对利奇疟原虫具有很强的抑制作用，耐药的确切机制尚不清楚。评估了137株李氏疟原虫分离株对氟奥匹胺的敏感性，发现杀菌剂的中值有效浓度（EC50）具有单峰频率分布，平均值为0.763±0.922μg/mL。将抗性突变体与等效亲本分离株进行比较，抗性突变体的生存适应性要低得多。虽然氟哌胺和其他卵菌抑制剂之间没有交叉耐药性，氟哌米特和氟吡康利有显著的正交叉耐药.根据彻底的调查，利奇假单胞菌有中等机会发展氟奥匹胺耐药性。P.litchii的VHA-a（PlVHA-a）中的点突变N771S和K847N存在于氟吡莫胺抗性突变体中，通过在敏感的辣椒分离株BYA5中进行定点诱变和分子对接，验证了PlVHA-a中赋予氟哌胺抗性的两个点突变。
