title: The Cucumber vein yellowing virus silencing suppressor P1b can functionally replace HCPro in Plum pox virus infection in a host-specific manner.
abstract: Plant viruses of the genera Potyvirus and Ipomovirus (Potyviridae family) use unrelated RNA silencing suppressors (RSS) to counteract antiviral RNA silencing responses. HCPro is the RSS of Potyvirus spp., and its activity is enhanced by the upstream P1 protein. Distinctively, the ipomovirus Cucumber vein yellowing virus (CVYV) lacks HCPro but contains two P1 copies in tandem (P1aP1b), the second of which functions as RSS. Using chimeras based on the potyvirus Plum pox virus (PPV), we found that P1b can functionally replace HCPro in potyviral infections of Nicotiana plants. Interestingly, P1a, the CVYV protein homologous to potyviral P1, disrupted the silencing suppression activity of P1b and reduced the infection efficiency of PPV in Nicotiana benthamiana. Testing the influence of RSS in host specificity, we found that a P1b-expressing chimera poorly infected PPV's natural host, Prunus persica. Conversely, P1b conferred on PPV chimeras the ability to replicate locally in cucumber, CVYV's natural host. The deleterious effect of P1a on PPV infection is host dependent, because the P1aP1b-expressing PPV chimera accumulated in cucumber to higher levels than PPV expressing P1b alone. These results demonstrate that a potyvirus can use different RSS, and that particular RSS and upstream P1-like proteins contribute to defining the virus host range.
authors.affiliation: Campus Universidad Autonoma de Madrid, Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Carbonell
authors.forename: Gabriela
authors.initials: G
authors.lastname: Dujovny
authors.forename: Juan Antonio
authors.initials: JA
authors.lastname: García
authors.forename: Adrian
authors.initials: A
authors.lastname: Valli
mesh_terms: D002678:Chimera; D018553:Cucumis sativus / Q000235:genetics / Q000821:virology*; D049452:Green Fluorescent Proteins; D058507:Host Specificity; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000821:virology; D030821:Plants, Genetically Modified; D017801:Plum Pox Virus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D019176:Potyviridae / Q000235:genetics*; D027861:Prunus / Q000235:genetics / Q000821:virology*; D034622:RNA Interference; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000821:virology; D014026:Nicotiana / Q000235:genetics / Q000821:virology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D012367:RNA, Viral; D014764:Viral Proteins; D049452:Green Fluorescent Proteins