title: Cauliflower mosaic virus protein P6 is a suppressor of RNA silencing.
abstract: We infected a transgenic Arabidopsis line (GxA), containing an amplicon-silenced 35S : : GFP transgene, with cauliflower mosaic virus (CaMV), a plant pararetrovirus with a DNA genome. Systemically infected leaves showed strong GFP fluorescence and amplicon transcripts were detectable in Northern blots, indicating that silencing of GFP had been suppressed during CaMV-infection. Transgenic Arabidopsis lines expressing CaMV protein P6, the major genetic determinant of symptom severity, were crossed with GxA. Progeny showed strong GFP fluorescence throughout and amplicon transcripts were detectable in Northern blots, indicating that P6 was suppressing local and systemic silencing. However, levels of 21 nt siRNAs derived from the GFP transgene were not reduced. In CaMV-infected plants, the P6 transgene did not reduce levels of CaMV leader-derived 21 and 24 nt siRNAs relative to levels of CaMV 35S RNA. These results demonstrate that CaMV can efficiently suppress silencing of a GFP transgene, and that P6 acts as a silencing suppressor.
authors.affiliation: Plant Science Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Love
authors.affiliation: Plant Science Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Janet
authors.initials: J
authors.lastname: Laird
authors.affiliation: Department of Pathology, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Justin
authors.initials: J
authors.lastname: Holt
authors.affiliation: Department of Pathology, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hamilton
authors.affiliation: Plant Science Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Ari
authors.initials: A
authors.lastname: Sadanandom
authors.affiliation: Plant Science Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK.
authors.forename: Joel J
authors.initials: JJ
authors.lastname: Milner
mesh_terms: D017360:Arabidopsis / Q000276:immunology / Q000378:metabolism / Q000821:virology*; D017796:Caulimovirus / Q000737:chemistry* / Q000472:pathogenicity; D015536:Down-Regulation; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology / Q000821:virology*; D018515:Plant Leaves / Q000276:immunology / Q000378:metabolism / Q000821:virology; D030821:Plants, Genetically Modified / Q000378:metabolism; D034622:RNA Interference / Q000502:physiology*; D034741:RNA, Small Interfering / Q000378:metabolism; D014764:Viral Proteins / Q000502:physiology*; D014774:Virulence
chemical_list: D034741:RNA, Small Interfering; D014764:Viral Proteins; D049452:Green Fluorescent Proteins