Role of efflux-mediated toxin resistance to trichothecenes is known in trichothecene-producing species. However, the role of trichothecene efflux pump homologues in non-producing fusaria such as F. oxysporum and F. proliferatum was not investigated in detail. Analysis of the homologues of trichothecene efflux pump from multiple fungal species allowed us to uncover and catalogue functional gene copies of conserved structure. Putative Tri12 candidates in Fusarium oxysporum and F. proliferatum were characterised via expression profiling in response to different trigger compounds, providing supporting evidence for role of Tri12 homologues in the resistance to trichothecenes. Our analysis of Tri12 phylogeny also suggests that efflux-mediated trichothecene resistance is likely to predate the divergence of Trichoderma and Fusarium species. On the regulatory level, we posit that the increased tolerance of trichothecenes by F. oxysporum is possibly related to the decoupling of Tri12 homologue expression from pH, due to the deletion of PACC/RIM101 transcription factor binding site in its promoter region.

中文翻译：

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外排泵是增殖镰孢和尖镰孢分离株中单端孢霉烯族化合物抗性的另一个来源。

在产生单端孢菌烯的物种中，外排介导的单端孢菌素毒素抗性的作用是已知的。然而，单端孢菌素外排泵同系物在非生产性镰孢菌（如尖镰孢菌和增殖镰刀菌）中的作用尚未得到详细研究。对多种真菌物种的单端孢菌素外排泵同源物的分析使我们能够发现并编录保守结构的功能基因拷贝。通过响应不同触发化合物的表达谱对尖孢镰刀菌和增殖镰刀菌中假定的 Tri12 候选物进行了表征，为Tri12同源物在单端孢霉烯族化合物抗性中的作用提供了支持证据。我们对Tri12系统发育的分析还表明，外流介导的单端孢菌素抗性可能早于木霉属和镰刀菌属物种的分化。在调控水平上，我们推测尖孢镰刀菌对单端孢霉烯族化合物的耐受性增加可能与Tri12同源物表达与 pH 的解偶联有关，这是由于其启动子区域中PACC/RIM101转录因子结合位点的缺失。