College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China.
Plant Dis. 2019 Jan;103(1):95-101. doi: 10.1094/PDIS-05-18-0754-RE. Epub 2018 Nov 6.
Hormetic effects of fungicides on mycelial growth and virulence of plant pathogenic fungi have been reported, but the effects of fungicide mixtures on virulence hormesis of plant pathogens remain to be investigated. In this study, hormetic effects of mixtures of carbendazim and iprodione on the virulence of two carbendazim-resistant isolates of Botrytis cinerea were determined. Spraying carbendazim alone at 3 to 800 μg/ml exhibited hormetic effects on virulence to cucumber leaves, and carbendazim at 10 μg/ml had the maximum stimulation of 16.7% for isolate HBtom451. Spraying iprodione alone at 0.0001 to 0.0625 μg/ml exhibited hormetic effects on virulence, and iprodione at 0.025 μg/ml had the maximum stimulation of 18.7% for isolate HBtom451. However, spraying simultaneously carbendazim at 800 μg/ml and iprodione at 0.0625 μg/ml showed inhibitory effects on virulence to cucumber leaves. The mixture of carbendazim at 3 μg/ml and iprodione at 0.0001 μg/ml had much higher virulence stimulations than either fungicide at the same concentration alone. The maximum stimulation for the mixtures occurred at 10 and 0.0005 μg/ml for carbendazim and iprodione, respectively, and these concentrations were much lower than the concentration of their respective fungicide alone eliciting the maximum stimulations. The maximum stimulation amplitude for the mixture was slightly higher than that of each fungicide alone. These results demonstrated that carbendazim and iprodione mainly had dose-additive rather than amplitude-additive interactions when sprayed simultaneously with regard to virulence stimulations. Studies on virulence stimulations for mycelia treated with fungicide in potato dextrose agar showed that the maximum stimulation for the mixtures occurred at concentrations much lower than the concentration of carbendazim alone, indicating a dose-additive interaction when compared with carbendazim hormesis. Studies on potential physiological mechanisms of hormesis showed that increased tolerance to HO may be one of the mechanisms for virulence hormesis for the mixtures of iprodione and carbendazim. These studies will advance our understanding of hormesis of fungicide mixtures.
杀菌剂对植物病原真菌菌丝生长和毒性的兴奋效应已有报道，但杀菌剂混合物对植物病原菌毒性兴奋效应的研究仍有待探讨。本研究测定了多菌灵和异菌脲混合物对两种多菌灵抗性灰葡萄孢分离物毒性的兴奋效应。单独喷施多菌灵 3 至 800μg/ml 对黄瓜叶片的毒性表现出兴奋效应，其中 10μg/ml 时对 HBtom451 分离物的刺激最大，为 16.7%。单独喷施异菌脲 0.0001 至 0.0625μg/ml 对毒性表现出兴奋效应，其中 0.025μg/ml 时对 HBtom451 分离物的刺激最大，为 18.7%。然而，同时喷施多菌灵 800μg/ml 和异菌脲 0.0625μg/ml 对黄瓜叶片的毒性表现出抑制作用。多菌灵 3μg/ml 和异菌脲 0.0001μg/ml 的混合物对毒性的刺激作用明显高于单独使用相同浓度的任一种杀菌剂。混合物的最大刺激作用分别发生在多菌灵和异菌脲浓度为 10μg/ml 和 0.0005μg/ml 时，这些浓度远低于各自单独使用最大刺激浓度。混合物的最大刺激幅度略高于单独使用每种杀菌剂的刺激幅度。这些结果表明，多菌灵和异菌脲同时喷施时，对毒性刺激主要表现为剂量相加作用，而不是幅度相加作用。在马铃薯葡萄糖琼脂中用杀菌剂处理菌丝体的毒性刺激研究表明，混合物的最大刺激作用发生在远低于多菌灵单独使用的浓度，与多菌灵的兴奋效应相比，表明存在剂量相加作用。对兴奋效应潜在生理机制的研究表明，对 HO 增加的耐受性可能是异菌脲和多菌灵混合物对毒性兴奋效应的机制之一。这些研究将增进我们对杀菌剂混合物兴奋效应的理解。
