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Effects of Trichothecene Production on the Plant Defense Response and Fungal Physiology: Overexpression of the Trichoderma arundinaceumtri4 Gene in T. harzianum

机译:单端孢菌素生产对植物防御反应和真菌生理的影响:哈茨木霉中木霉arundinaceumtri4基因的过表达

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Trichothecenes are fungal sesquiterpenoid compounds, the majority of which have phytotoxic activity. They contaminate food and feed stocks, resulting in potential harm to animals and human beings. Trichoderma brevicompactum and T. arundinaceum produce trichodermin and harzianum A (HA), respectively, two trichothecenes that show different bioactive properties. Both compounds have remarkable antibiotic and cytotoxic activities, but in addition, trichodermin is highly phytotoxic, while HA lacks this activity when analyzed in vivo . Analysis of Fusarium trichothecene intermediates led to the conclusion that most of them, with the exception of the hydrocarbon precursor trichodiene (TD), have a detectable phytotoxic activity which is not directly related to the structural complexity of the intermediate. In the present work, the HA intermediate 12,13-epoxytrichothec-9-ene (EPT) was produced by expression of the T. arundinaceum tri4 gene in a transgenic T. harzianum strain that already produces TD after transformation with the T. arundinaceum tri5 gene. Purified EPT did not show antifungal or phytotoxic activity, while purified HA showed both antifungal and phytotoxic activities. However, the use of the transgenic T. harzianum tri4 strain induced a downregulation of defense-related genes in tomato plants and also downregulated plant genes involved in fungal root colonization. The production of EPT by the transgenic tri4 strain raised levels of erg1 expression and reduced squalene accumulation while not affecting levels of ergosterol. Together, these results indicate the complex interactions among trichothecene intermediates, fungal antagonists, and host plants.
机译:毛滴虫是真菌的倍半萜类化合物,其中大多数具有植物毒性活性。它们污染食品和饲料,对动物和人类造成潜在伤害。短木霉菌和短梗木霉分别产生曲霉菌素和哈氏菌素A(HA),这两种曲霉菌素具有不同的生物活性。两种化合物均具有显着的抗生素和细胞毒性活性,但此外,曲霉毒素具有很高的植物毒性,而当在体内进行分析时,HA缺乏这种活性。对镰孢镰刀菌属中间体的分析得出的结论是,除烃前体trichodiene(TD)以外,它们中的大多数都具有可检测到的植物毒性活性,而活性与中间体的结构复杂性没有直接关系。在当前的工作中,HA中间体12,13-环氧三苯并噻吩-9-烯(EPT)是通过将arundinaceum tri4基因表达在转基因的T. harzianum菌株中产生的,该菌株在用arundinaceum tri5转化后已经产生了TD。基因。纯化的EPT不显示抗真菌或植物毒性活性,而纯化的HA则显示抗真菌和植物毒性活性。然而,转基因哈茨木霉tri4菌株的使用诱导了番茄植株中防御相关基因的下调,并且也下调了与真菌根定植有关的植物基因。转基因tri4菌株产生的EPT可提高erg1表达水平并减少角鲨烯积累,同时不影响麦角固醇的水平。总之,这些结果表明天花粉中间体,真菌拮抗剂和宿主植物之间的复杂相互作用。

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