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Triticum mosaic poacevirus enlists P1 rather than HC-Pro to suppress RNA silencing-mediated host defense

Author:
Tatineni, Satyanarayana, Qu, Feng, Li, Ruhui, Morris, T. Jack, French, Roy
Source:
Virology 2012 v.433 no.1 pp. 104
ISSN:
0042-6822
Subject:
Turnip mosaic virus, double-stranded RNA, gene silencing, hosts, pathogenicity, proteinases, proteins, resistance mechanisms, viruses
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.
Agid:
55924
Handle:
10113/55924