University of Ljubljana, Biotechnical Faculty, Agronomy Department, Ljubljana, 1000, Slovenia.
Slovenian Institute of Hop Research and Brewing, Žalec, 3310, Slovenia.
Sci Rep. 2019 Jun 17;9(1):8651. doi: 10.1038/s41598-019-44494-8.
The conserved RNA interference mechanism (RNAi) in the fungal kingdom has become a focus of intense scientific investigation. The three catalytic core components, Dicer-like (DCL), Argonaute (AGO), and RNA-dependent RNA polymerase (RdRP), and their associated small interfering RNA molecules (siRNAs) have been identified and characterised in several fungal species. Recent studies have proposed that RNAi is a major contributor to the virulence of fungal pathogens as a result of so-called trans-kingdom RNA silencing. In the present study, we report on the existence of three core RNAi proteins in the pathogenic plant fungus Verticillium nonalfalfae, which is a soilborne plant pathogen that causes severe wilting disease in hops (Humulus lupulus L.). Two DCL proteins, two AGO proteins, and two RdRP proteins were identified, and their conserved RNAi domains were characterised. Our phylogeny results confirm the existing taxonomic relationships in the Ascomycete fungal phylum and show that the fungi of the Hypocreomycetidae subclass of the Sordariomycetes class have high amino acid sequence similarity. The expression analysis revealed a potential role of RNAi in the pathogenicity of the fungi, since all the RNAi genes were highly upregulated in the highly virulent isolate T2 and were also differentially expressed in the V. nonalfalfae-susceptible Celeia and V. nonalfalfae-resistant Wye Target cultivars.
真菌王国中保守的 RNA 干扰机制（RNAi）已成为科学研究的热点。三种催化核心成分，Dicer-like（DCL）、Argonaute（AGO）和 RNA 依赖性 RNA 聚合酶（RdRP）及其相关的小干扰 RNA 分子（siRNAs）已在几种真菌物种中被鉴定和表征。最近的研究表明，由于所谓的跨物种 RNA 沉默，RNAi 是真菌病原体毒力的主要贡献者。在本研究中，我们报告了致病植物真菌Verticillium nonalfalfae 中存在三种核心 RNAi 蛋白的情况，该真菌是一种土壤传播的植物病原体，可导致啤酒花（Humulus lupulus L.）严重萎蔫病。鉴定出了两种 DCL 蛋白、两种 AGO 蛋白和两种 RdRP 蛋白，并对其保守的 RNAi 结构域进行了表征。我们的系统发育结果证实了子囊菌真菌门中的现有分类关系，并表明 Sordariomycetes 纲中 Hypocreomycetidae 子类的真菌具有高度相似的氨基酸序列。表达分析表明 RNAi 在真菌的致病性中可能发挥作用，因为所有 RNAi 基因在高毒力分离株 T2 中高度上调，并且在 V. nonalfalfae 易感品种 Celeia 和 V. nonalfalfae 抗性 Wye Target 品种中也存在差异表达。
