A novel ilarvirus protein CP-RT is expressed via stop codon readthrough and suppresses RDR6-dependent RNA silencing

Ilarviruses are a relatively understudied but important group of plant RNA viruses that includes a number of crop pathogens. Their genomes comprise three RNA segments encoding two replicase subunits, movement protein, coat protein (CP), and (in some ilarvirus subgroups) a protein that suppresses RNA...

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Bibliographic Details
Published in:PLoS pathogens 2024-05, Vol.20 (5), p.e1012034
Main Authors: Lukhovitskaya, Nina, Brown, Katherine, Hua, Lei, Pate, Adrienne E, Carr, John P, Firth, Andrew E
Format: Article
Language:English
Subjects:
Analysis
Asparagus
Biology and life sciences
Capsid Proteins - genetics
Capsid Proteins - metabolism
Coat protein
Codon
Codon, Terminator - genetics
Control
Disease transmission
Disseminated infection
Gene expression
Genomes
Genomics
Health aspects
Identification and classification
Ilarvirus - genetics
Infections
Medical research
Medicine, Experimental
Meristems
Movement protein
Nicotiana - genetics
Nicotiana - metabolism
Nicotiana - virology
Open reading frames
Persistent infection
Plant Diseases - genetics
Plant Diseases - virology
Prevention
Proteins
Replicase
RNA Interference
RNA polymerase
RNA viruses
RNA, Viral - genetics
RNA, Viral - metabolism
RNA-Dependent RNA Polymerase - genetics
RNA-Dependent RNA Polymerase - metabolism
RNA-mediated interference
Stop codon
Subgroups
Viral Proteins - genetics
Viral Proteins - metabolism
Viruses
Zinc finger proteins
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Description
Summary:Ilarviruses are a relatively understudied but important group of plant RNA viruses that includes a number of crop pathogens. Their genomes comprise three RNA segments encoding two replicase subunits, movement protein, coat protein (CP), and (in some ilarvirus subgroups) a protein that suppresses RNA silencing. Here we report that, in many ilarviruses, RNA3 encodes an additional protein (termed CP-RT) as a result of ribosomal readthrough of the CP stop codon into a short downstream readthrough (RT) ORF. Using asparagus virus 2 as a model, we find that CP-RT is expressed in planta where it functions as a weak suppressor of RNA silencing. CP-RT expression is essential for persistent systemic infection in leaves and shoot apical meristem. CP-RT function is dependent on a putative zinc-finger motif within RT. Replacing the asparagus virus 2 RT with the RT of an ilarvirus from a different subgroup restored the ability to establish persistent infection. These findings open up a new avenue for research on ilarvirus silencing suppression, persistent meristem invasion and vertical transmission.
ISSN:1553-7374
1553-7366
1553-7374
DOI:10.1371/journal.ppat.1012034