Department Biosciences and Landscape Architecture, Ghent University College/Ghent University Association, Schoonmeersstraat 52, B-9000 Gent, Belgium.
BMC Microbiol. 2010 Apr 15;10:112. doi: 10.1186/1471-2180-10-112.
Fusarium head blight is a very important disease of small grain cereals with F. graminearum as one of the most important causal agents. It not only causes reduction in yield and quality but from a human and animal healthcare point of view, it produces mycotoxins such as deoxynivalenol (DON) which can accumulate to toxic levels. Little is known about external triggers influencing DON production.
In the present work, a combined in vivo/in vitro approach was used to test the effect of sub lethal fungicide treatments on DON production. Using a dilution series of prothioconazole, azoxystrobin and prothioconazole + fluoxastrobin, we demonstrated that sub lethal doses of prothioconazole coincide with an increase in DON production 48 h after fungicide treatment. In an artificial infection trial using wheat plants, the in vitro results of increased DON levels upon sub lethal prothioconazole application were confirmed illustrating the significance of these results from a practical point of view. In addition, further in vitro experiments revealed a timely hyperinduction of H2O2 production as fast as 4 h after amending cultures with prothioconazole. When applying H2O2 directly to germinating conidia, a similar induction of DON-production by F. graminearum was observed. The effect of sub lethal prothioconazole concentrations on DON production completely disappeared when applying catalase together with the fungicide.
These cumulative results suggest that H2O2 induced by sub lethal doses of the triazole fungicide prothioconazole acts as a trigger of DON biosynthesis. In a broader framework, this work clearly shows that DON production by the plant pathogen F. graminearum is the result of the interaction of fungal genomics and external environmental triggers.
镰刀菌穗腐病是一种非常重要的小谷物病害，禾谷镰刀菌是最重要的病原体之一。它不仅导致产量和质量下降，而且从人类和动物健康的角度来看，它还会产生霉菌毒素，如脱氧雪腐镰刀菌烯醇（DON），这些毒素可能会积累到有毒水平。目前对于影响 DON 产生的外部触发因素知之甚少。
在本研究中，采用体内/体外联合方法测试了亚致死剂量杀菌剂处理对 DON 产生的影响。使用一系列噻呋酰胺、唑菌胺酯和噻呋酰胺+氟环唑的稀释系列，我们证明了亚致死剂量的噻呋酰胺与杀菌剂处理后 48 小时 DON 产量增加相一致。在使用小麦植株的人工感染试验中，体外结果证实了亚致死剂量噻呋酰胺处理导致 DON 水平升高的重要性，从实际角度说明了这些结果的意义。此外，进一步的体外实验表明，在添加噻呋酰胺后，H2O2 的产生会迅速诱导，最快在 4 小时内。当将 H2O2 直接应用于发芽的分生孢子时，观察到禾谷镰刀菌类似地诱导 DON 产生。当用过氧化氢酶与杀菌剂一起应用时，亚致死浓度的噻呋酰胺对 DON 产生的影响完全消失。
这些累积的结果表明，亚致死剂量的三唑类杀菌剂噻呋酰胺诱导的 H2O2 作为 DON 生物合成的触发因素。从更广泛的角度来看，这项工作清楚地表明，植物病原菌禾谷镰刀菌产生 DON 是真菌基因组和外部环境触发因素相互作用的结果。
