title: Mild and severe cereal yellow dwarf viruses differ in silencing suppressor efficiency of the P0 protein.
abstract: Viral pathogenicity has often been correlated to the expression of the viral encoded-RNA silencing suppressor protein (SSP). The silencing suppressor activity of the P0 protein encoded by cereal yellow dwarf virus-RPV (CYDV-RPV) and -RPS (CYDV-RPS), two poleroviruses differing in their symptomatology was investigated. CYDV-RPV displays milder symptoms in oat and wheat whereas CYDV-RPS is responsible for more severe disease. We showed that both P0 proteins (P0(CY-RPV) and P0(CY-RPS)) were able to suppress local RNA silencing induced by either sense or inverted repeat transgenes in an Agrobacterium tumefaciens-mediated expression assay in Nicotiana benthamiana. P0(CY-RPS) displayed slightly higher activity. Systemic spread of the silencing signal was not impaired. Analysis of short-interfering RNA (siRNA) abundance revealed that accumulation of primary siRNA was not affected, but secondary siRNA levels were reduced by both CYDV P0 proteins, suggesting that they act downstream of siRNA production. Correlated with this finding we showed that both P0 proteins partially destabilized ARGONAUTE1. Finally both P0(CY-RPV) and P0(CY-RPS) interacted in yeast cells with ASK2, a component of an E3-ubiquitin ligase, with distinct affinities.
authors.affiliation: Institut de Biologie Moléculaire des Plantes CNRS-UPR 2357, associée à l'Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France; Plant Virology Research Center, College of Agriculture, Shiraz University, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Almasi
authors.affiliation: Institut de Biologie Moléculaire des Plantes CNRS-UPR 2357, associée à l'Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France; Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011, USA.
authors.forename: W Allen
authors.initials: WA
authors.lastname: Miller
authors.affiliation: Institut de Biologie Moléculaire des Plantes CNRS-UPR 2357, associée à l'Université de Strasbourg, 12 rue du Général Zimmer, 67084 Strasbourg, France. Electronic address: Veronique.Ziegler-Graff@ibmp-cnrs.unistra.fr.
authors.forename: Véronique
authors.initials: V
authors.lastname: Ziegler-Graff
mesh_terms: D018554:Avena / Q000235:genetics / Q000821:virology; D054884:Host-Pathogen Interactions; D052679:Luteoviridae / Q000235:genetics / Q000378:metabolism*; D010935:Plant Diseases / Q000235:genetics / Q000821:virology*; D034622:RNA Interference; D014026:Nicotiana / Q000235:genetics* / Q000821:virology; D014908:Triticum / Q000235:genetics / Q000821:virology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D014764:Viral Proteins
keywords: ARGONAUTE 1; CYDV; P0 protein; Polerovirus; RNA silencing suppressor; SKP