Zhou Feng, Zhou Huan-Huan, Han Ao-Hui, Guo Kou-Yun, Liu Tian-Cheng, Wu Yan-Bing, Hu Hai-Yan, Li Cheng-Wei
Henan Engineering Research Center of Crop Genome Editing/Henan International Joint Laboratory of Plant Genetic Improvement and Soil Remediation, Henan Institute of Science and Technology, Xinxiang 453003, China.
Postdoctoral Research Base, Henan Institute of Science and Technology, Xinxiang 453003, China.
J Fungi (Basel). 2022 Dec 30;9(1):62. doi: 10.3390/jof9010062.
Fusarium head blight (FHB), which is primarily caused by Fusarium graminearum, is a widespread and devastating disease of wheat. In the absence of resistant varieties, the control of FHB relies heavily on the application of fungicides, and the new generation SDHI fungicide, pydiflumetofen, has recently been registered in China for the control of FHB in wheat. The current study explored three genetically stable, highly resistant laboratory mutants (S2-4-2R, S27-3R, and S28-2R, with EC50 values of 25.10, 28.57, and 19.22 μg/mL, respectively) to investigate the potential risks associated with pydiflumetofen resistance. Although the mycelial growth of the mutants differed little compared to their parental isolates, the study found that the resistant mutants exhibited significantly reduced (p < 0.05) levels of sporulation and pathogenicity, which suggests a significant fitness cost associated with pydiflumetofen resistance in F. graminearum. Sequence analysis of the Sdh target protein identified numerous amino acid substitutions in the predicted sequences of the four subunits: FgSdhA, FgSdhB, FgSdhC, and FgSdhD. Indeed, the mutants were found to have a series of substitution in multiple subunits such that all three exhibited five identical changes, including Y182F in the FgSdhA subunit; H53Q, C90S, and A94V in FgSdhB; and S31F in FgSdhC. In addition, gene expression analysis revealed that all of the FgSdh genes had significantly altered expression (p < 0.05), particularly FgSdhA and FgdhC, which exhibited remarkably low levels of expression. However, the study found no evidence of cross-resistance between pydiflumetofen and tebuconazole, fludioxonil, prochloraz, fluazinam, carbendazim, pyraclostrobin, or difenoconazole, which indicates that these fungicides, either in rotation or combination with pydiflumetofen, could mitigate the risk of resistance emerging and provide ongoing control of FHB to ensure high and stable wheat yields.
赤霉病（FHB）主要由禾谷镰刀菌引起，是一种广泛传播且极具破坏性的小麦病害。在缺乏抗性品种的情况下，赤霉病的防治严重依赖杀菌剂的使用，新一代琥珀酸脱氢酶抑制剂（SDHI）杀菌剂氟吡菌酰胺最近已在中国登记用于防治小麦赤霉病。本研究探究了三个遗传稳定、高抗的实验室突变体（S2-4-2R、S27-3R和S28-2R，其半数有效浓度（EC50）值分别为25.10、28.57和19.22μg/mL），以调查与氟吡菌酰胺抗性相关的潜在风险。尽管与亲本菌株相比，突变体的菌丝生长差异不大，但研究发现抗性突变体的产孢量和致病性显著降低（p<0.05），这表明禾谷镰刀菌对氟吡菌酰胺的抗性存在显著的适合度代价。对琥珀酸脱氢酶（Sdh）靶蛋白的序列分析在四个亚基（FgSdhA、FgSdhB、FgSdhC和FgSdhD）的预测序列中鉴定出许多氨基酸替换。实际上，发现突变体在多个亚基中存在一系列替换，使得所有三个突变体都表现出五个相同的变化，包括FgSdhA亚基中的Y182F；FgSdhB中的H53Q、C90S和A94V；以及FgSdhC中的S31F。此外，基因表达分析表明，所有FgSdh基因的表达均有显著改变（p<0.05），尤其是FgSdhA和FgdhC，其表达水平极低。然而，该研究未发现氟吡菌酰胺与戊唑醇、咯菌腈、咪鲜胺、氟啶胺、多菌灵、吡唑醚菌酯或苯醚甲环唑之间存在交叉抗性的证据，这表明这些杀菌剂无论是轮用还是与氟吡菌酰胺混用，都可以降低抗性出现的风险，并持续防治赤霉病以确保小麦高产稳产。
