The cereal infecting fungus Fusarium graminearum is predicted to possess a single homologue of plant RALF (rapid alkalinisation factor) peptides. Fusarium mutant strains lacking FgRALF were generated and found to exhibit wildtype virulence on wheat and Arabidopsis floral tissue. Arabidopsis lines constitutively overexpressing FgRALF exhibited no obvious change in susceptibility to F. graminearum leaf infection. In contrast transient virus-mediated over-expression (VOX) of FgRALF in wheat prior to F. graminearum infection, slightly increased the rate of fungal colonisation of floral tissue. Ten putative Feronia (FER) receptors of RALF peptide were identified bioinformatically in hexaploid wheat (Triticum aestivum). Transient silencing of two wheat FER homoeologous genes prior to F. graminearum inoculation did not alter the subsequent interaction outcome. Collectively, our VOX results show that the fungal RALF peptide may be a minor contributor in F. graminearum virulence but results from fungal gene deletion experiments indicate potential functional redundancy within the F. graminearum genome. We demonstrate that virus-mediated over-expression is a useful tool to provide novel information about gene/protein function when results from gene deletion/disruption experimentation were uninformative.

中文翻译：

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禾谷镰刀菌中植物快速碱化因子 (RALF) 肽同系物的功能评估

预测谷物感染真菌禾谷镰刀菌具有单一的植物 RALF（快速碱化因子）肽同系物。产生了缺乏 FgRALF 的镰刀菌突变株，并发现它们对小麦和拟南芥花组织表现出野生型毒力。组成性过表达 FgRALF 的拟南芥株系对禾谷镰刀菌叶片感染的易感性没有明显变化。相比之下，在禾谷镰刀菌感染之前，小麦中 FgRALF 的瞬时病毒介导过表达 (VOX) 略微增加了花卉组织的真菌定植率。在六倍体小麦 (Triticum aestivum) 中通过生物信息学鉴定了 RALF 肽的 10 种推定的 Feronia (FER) 受体。两个小麦 FER 同源基因在 F. 接种禾本科植物并没有改变随后的相互作用结果。总的来说，我们的 VOX 结果表明真菌 RALF 肽可能是禾谷镰刀菌毒力的次要贡献者，但真菌基因缺失实验的结果表明禾谷镰刀菌基因组内存在潜在的功能冗余。我们证明了病毒介导的过度表达是一种有用的工具，可以在基因缺失/破坏实验的结果不提供信息时提供有关基因/蛋白质功能的新信息。