title: Cowpea mosaic virus RNA-1 acts as an amplicon whose effects can be counteracted by a RNA-2-encoded suppressor of silencing.
abstract: Lines of Nicotiana benthamiana transgenic for full-length copies of both Cowpea mosaic virus (CPMV) genomic RNAs, either singly or together, have been produced. Plants transgenic for both RNAs developed symptoms characteristic of a CPMV infection. When plants transgenic for RNA-1 were agro-inoculated with RNA-2, no infection developed and the plants were also resistant to challenge with CPMV. By contrast, plants transgenic for RNA-2 became infected when agro-inoculated with RNA-1 and were fully susceptible to CPMV infection. The resistance of RNA-1 transgenic plants was shown to be related to the ability of RNA-1 to self-replicate and act as an amplicon. The ability of transgenically expressed RNA-2 to counteract the amplicon effect suggested that it encodes a suppressor of posttranscriptional gene silencing (PTGS). By examining the ability of portions of RNA-2 to reverse PTGS in N. benthamiana, we have identified the small (S) coat protein as the CPMV RNA-2-encoded suppressor of PTGS.
authors.affiliation: John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Jef
authors.initials: J
authors.lastname: Grainger
authors.forename: M Carmen
authors.initials: MC
authors.lastname: Cañizares
authors.forename: Susan M
authors.initials: SM
authors.lastname: Angell
authors.forename: George P
authors.initials: GP
authors.lastname: Lomonossoff
mesh_terms: D036022:Capsid Proteins / Q000235:genetics / Q000378:metabolism; D017798:Comovirus / Q000235:genetics* / Q000502:physiology*; D005816:Genetic Complementation Test; D010935:Plant Diseases / Q000821:virology*; D018515:Plant Leaves / Q000235:genetics / Q000821:virology; D053830:Plant Viral Movement Proteins; D030821:Plants, Genetically Modified / Q000235:genetics / Q000821:virology; D034622:RNA Interference; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000821:virology; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D036022:Capsid Proteins; D053830:Plant Viral Movement Proteins; D012367:RNA, Viral; D014764:Viral Proteins