Henan Engineering Research Center of Green Pesticide Creation and Pesticide Residue Monitoring by Intelligent Sensor, Henan Institute of Science and Technology, Xinxiang, 453003, China.
Postdoctoral Research Base, Henan Institute of Science and Technology, Xinxiang, 453003, China.
BMC Plant Biol. 2024 Aug 21;24(1):789. doi: 10.1186/s12870-024-05206-1.
The Fusarium head blight caused by Fusarium graminearum results in reduced crop yields and the potential for vomitoxin contamination, which poses a risk to both human and livestock health. The primary method of control relies on the application of chemical fungicides.
The current study found that the tebuconazole sensitivity of 165 F. graminearum isolates collected from the Huang-Huai-Hai region of China between 2019 and 2023 ranged from 0.005 to 2.029 µg/mL, with an average EC value of 0.33 ± 0.03 µg/mL. The frequency distribution conformed to a unimodal curve around the mean, and therefore provides a useful reference for monitoring the emergence of tebuconazole resistance in field populations of F. graminearum. No cross-resistance was detected between tebuconazole and other unrelated fungicides such as flutriafol, propiconazole and fluazinam, but there was a clear negative cross-resistance with triazole fungicides including fludioxonil, epoxiconazole, hexaconazole, and metconazole. Analysis of five tebuconazole-resistant mutants produced under laboratory conditions indicated that although the mycelial growth of the mutants were significantly (p < 0.05) reduced, spore production and germination rates could be significantly (p < 0.05) increased. However, pathogenicity tests confirmed a severe fitness cost associated with tebuconazole resistance, as all of the mutants completely loss the ability to infect host tissue. Furthermore, in general the resistant mutants were found to have increased sensitivity to abiotic stress, such as ionic and osmotic stress, though not to Congo red and oxidative stress, to which they were more tolerant. Meanwhile, molecular analysis identified several point mutations in the CYP51 genes of the mutants, which resulted in two substitutions (I281T, and T314A) in the predicted sequence of the FgCYP51A subunit, as well as seven (S195F, Q332V, V333L, L334G, M399T, E507G, and E267G) in the FgCYP51C subunit. In addition, it was also noted that the expression of the CYP51 genes in one of the mutants, which lacked point mutations, was significantly up-regulated in response to tebuconazole treatment.
These results provide useful data that allow for more rational use of tebuconazole in the control of F. graminearum, as well as for more effective monitoring of fungicide resistance in the field.
镰刀菌禾谷孢霉引起的赤霉病会导致作物减产和呕吐毒素污染的风险，这对人类和牲畜的健康都构成了威胁。主要的控制方法依赖于化学杀真菌剂的应用。
本研究发现，2019 年至 2023 年期间，在中国黄淮海地区采集的 165 株禾谷镰刀菌对戊唑醇的敏感性范围为 0.005 至 2.029μg/mL，平均 EC 值为 0.33±0.03μg/mL。频率分布呈单峰曲线，因此为监测田间禾谷镰刀菌对戊唑醇的抗性出现提供了有用的参考。戊唑醇与其他无关联的杀真菌剂（如氟环唑、丙环唑和氟唑菌酰胺）之间未检测到交叉抗性，但与三唑类杀真菌剂（如氟啶酮、环丙唑醇、己唑醇和戊唑醇）存在明显的负交叉抗性。在实验室条件下产生的五个戊唑醇抗性突变体的分析表明，尽管突变体的菌丝生长显著（p<0.05）降低，但孢子产生和萌发率可显著（p<0.05）增加。然而，致病性测试证实了戊唑醇抗性相关的严重适应代价，因为所有突变体完全丧失了感染宿主组织的能力。此外，一般来说，抗性突变体对离子和渗透胁迫等非生物胁迫的敏感性增加，但对刚果红和氧化应激的敏感性降低，对这些胁迫的耐受性更强。同时，分子分析鉴定出突变体 CYP51 基因中的几个点突变，导致 FgCYP51A 亚基预测序列中的两个取代（I281T 和 T314A），以及 FgCYP51C 亚基中的七个取代（S195F、Q332V、V333L、L334G、M399T、E507G 和 E267G）。此外，还注意到，在一个缺乏点突变的突变体中，CYP51 基因的表达在戊唑醇处理后显著上调。
这些结果提供了有用的数据，使我们能够更合理地使用戊唑醇来控制禾谷镰刀菌，以及更有效地监测田间杀真菌剂抗性。
