Stepwise accumulation of mutations in CesA3 in Phytophthora sojae results in increasing resistance to CAA fungicides.
Stepwise accumulation of mutations in CesA3 in Phytophthora sojae results in increasing resistance to CAA fungicides.
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大豆疫霉中 CesA3 突变的逐步积累导致对 CAA 杀菌剂的耐药性增加
DOI：
10.1111/eva.13176
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发表时间：
2021-04
影响因子：
4.1
通讯作者：
Liu X
中科院分区：
文献类型：
--
作者：
Cai M;Zhang C;Wang W;Peng Q;Song X;Tyler BM;Liu X
氟吗啉是一种对卵菌具有高效活性的羧酸酰胺类杀菌剂。然而，从低抗性到高抗性的CAAs演变从未报道过。本研究探讨了大豆疫霉菌对氟吗啉的抗性进化基础。共收集120个大豆疫霉菌分离物，并对其进行了氟吗啉敏感性评价。虽然在田间分离株中未发现自发抗性，但在氟吗啉改良培养基上的适应导致选择了5种对CAA表现出不同程度抗性的稳定突变类型。当野生型分离株暴露于低浓度的氟吗啉时，获得了表现出最低抗性水平的I型，但直接暴露于更高浓度时没有获得抗性突变体。然而，当I型暴露于更高浓度的氟吗啉时，获得了更耐药的类型（II、III、IV和V型）。当重复整个筛选过程时，获得了类似的结果，这意味着大豆疫霉对氟吗啉的抗性进化可能是一个两步过程，其中高抗性表型可以从低抗性表型逐渐发展。进一步的分子机制研究证实，氟吗啉高抗性菌株的进化是以Ⅰ型为中介，通过其靶蛋白CAAs（CesA3）突变的积累逐步进行的。总之，我们的研究结果表明，在田间应用低比例的氟吗啉可能导致选择低抗性I型分离株，但提高剂量以保持相当的控制水平可能引起更耐药的II，III，IV和V型分离株的快速进化，CesA3突变逐步积累，这将使氟吗啉作为控制方法无效。应实施预防性抗性管理策略。研究中描述的现象可能具有更广泛的生物学意义。
Flumorph is a carboxylic acid amide (CAA) fungicide with high activity against oomycetes. However, evolution to CAAs from low resistance to high resistance has never been reported. This study investigated the basis of resistance evolution of flumorph in Phytophthora sojae. Total of 120 P. sojae isolates were collected and their sensitivity to flumorph was evaluated. Although no spontaneous resistance was found among the field isolates, adaptation on flumorph‐amended media resulted in the selection of five stable mutant types exhibiting varying degrees of resistance to CAAs. Type I, which exhibited the lowest resistance level, was obtained when the wild‐type isolate was exposed to a low concentration of flumorph, but no resistant mutants were obtained by direct exposure to higher concentrations. However, the more resistant types (Type II, III, IV and V) were obtained when Type I were exposed to higher concentrations of flumorph. Similar results were obtained when the entire screening process was repeated, which implied that evolution of resistance to flumorph in P. sojae could be a two‐step process, where high resistance phenotypes could develop gradually from low resistance ones. Further investigation into molecular mechanism strongly confirmed that evolution of isolates highly resistant to flumorph occurs in a stepwise process with Type I as intermediary, through accumulation of mutations in their target protein of CAAs (CesA3). Together, our findings indicate that application of low rates of flumorph in field could result in selection of low resistance Type I isolates, but that raising dosage to maintain comparable levels of control could elicit rapid evolution of more resistant Type II, III, IV and V isolates with stepwise accumulation of mutations in CesA3, which would render flumorph ineffective as a control method. Precautionary resistance management strategy should be implemented. The phenomenon described in the study could have broader biological significance.
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影响因子：
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通讯作者：
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