Articles
Studying RNAi in pathogenic hop fungi Verticillium nonalfalfae
Article number
1328_5
Pages
37 – 46
Language
English
Abstract
Most fungi of the genus Verticillium are soil-born pathogenic plant fungi causing severe wilting disease on many important crops worldwide.
The species Verticillium nonalfalfae in particular is a causal agent of verticillium wilt of hops (Humulus lupulus L.), where the highly virulent pathotypes cause complete dieback of entire hop fields.
It was recently demonstrated that the pathogenic fungi use RNA interference (RNAi) as one of their virulence mechanisms, and export small RNA signals into the host plant to mediate host immune responses.
In the present study, RNAi was studied for the first time in V. nonalfalfae. A BLAST analysis and manual gene model curation resulted in the identification of elements of the RNA-induced silencing complex, two Dicer-like, and two Argonaut as well as two RNA-dependent RNA polymerase proteins were identified in the annotated V. nonalfalfae genome.
The expression analysis revealed a potential role of the RNAi core components for the pathogenicity of the fungi, as all the RNAi genes are significantly upregulated in highly virulent isolate T2. Additionally, the small RNAs originating from transposable elements were searched in the reference V. nonalfalfae genome.
The first repetitive elements in the genome were annotated by Repeat Masker.
The LTR-retrotransposons are the most abundant group of mobile elements in the fungal genome with the highest small RNA read coverage; this suggests a possible origin of the small RNAs in V. nonalfalfae from these particular group of transposable elements.
The species Verticillium nonalfalfae in particular is a causal agent of verticillium wilt of hops (Humulus lupulus L.), where the highly virulent pathotypes cause complete dieback of entire hop fields.
It was recently demonstrated that the pathogenic fungi use RNA interference (RNAi) as one of their virulence mechanisms, and export small RNA signals into the host plant to mediate host immune responses.
In the present study, RNAi was studied for the first time in V. nonalfalfae. A BLAST analysis and manual gene model curation resulted in the identification of elements of the RNA-induced silencing complex, two Dicer-like, and two Argonaut as well as two RNA-dependent RNA polymerase proteins were identified in the annotated V. nonalfalfae genome.
The expression analysis revealed a potential role of the RNAi core components for the pathogenicity of the fungi, as all the RNAi genes are significantly upregulated in highly virulent isolate T2. Additionally, the small RNAs originating from transposable elements were searched in the reference V. nonalfalfae genome.
The first repetitive elements in the genome were annotated by Repeat Masker.
The LTR-retrotransposons are the most abundant group of mobile elements in the fungal genome with the highest small RNA read coverage; this suggests a possible origin of the small RNAs in V. nonalfalfae from these particular group of transposable elements.
Publication
Authors
T. Jeseničnik, N. Štajner, S. Radišek, A. Kumar-Mishra, J. Jakše
Keywords
pathogenic fungi, Verticillium wilt, RNA interference, DCL, AGO, RdRP, small RNAs
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