title: Triticum mosaic poacevirus enlists P1 rather than HC-Pro to suppress RNA silencing-mediated host defense.
abstract: Triticum mosaic virus (TriMV) is the type species of the newly established Poacevirus genus in the family Potyviridae. In this study, we demonstrate that in contrast to the helper component-proteinase (HC-Pro) of Potyvirus species, the P1 proteins of TriMV and Sugarcane streak mosaic poacevirus function in suppression of RNA silencing (SRS). TriMV P1 effectively suppressed silencing induced by single- or double-stranded RNAs (ss/ds RNAs), and disrupted the systemic spread of silencing signals at a step after silencing signal production. Interestingly, contrary to enhanced SRS activity of potyviral HC-Pro by co-expression with P1, the presence of TriMV HC-Pro reduced SRS activity of TriMV P1. Furthermore, TriMV P1 suppressed systemic silencing triggered by dsRNA more efficiently than the HC-Pro of Turnip mosaic potyvirus. Furthermore, TriMV P1 enhanced the pathogenicity of a heterologous virus. Our results established poaceviral P1 as a potent RNA silencing suppressor that probably employs a novel mechanism to suppress RNA silencing-based antiviral defense.
authors.affiliation: United States Department of Agriculture-Agricultural Research Service and Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68583, United States. satya.tatineni@ars.usda.gov
authors.forename: Satyanarayana
authors.initials: S
authors.lastname: Tatineni
authors.forename: Feng
authors.initials: F
authors.lastname: Qu
authors.forename: Ruhui
authors.initials: R
authors.lastname: Li
authors.forename: T Jack
authors.initials: TJ
authors.lastname: Morris
authors.forename: Roy
authors.initials: R
authors.lastname: French
mesh_terms: D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000235:genetics*; D015967:Gene Expression Regulation, Viral; D057131:Immune Evasion; D010935:Plant Diseases / Q000276:immunology / Q000821:virology; D017800:Potyvirus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D034622:RNA Interference / Q000276:immunology; D012330:RNA, Double-Stranded / Q000235:genetics / Q000276:immunology; D031786:Saccharum / Q000276:immunology / Q000821:virology; D014026:Nicotiana / Q000276:immunology / Q000821:virology*; D014908:Triticum / Q000276:immunology / Q000821:virology*; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics*
chemical_list: C409826:P1 protein, potyvirus; D012330:RNA, Double-Stranded; D014764:Viral Proteins; D003546:Cysteine Endopeptidases; C072775:HC-Pro protein, potyvirus