A viral movement protein prevents spread of the gene silencing signal in Nicotiana benthamiana.
In plants, viruses induce an RNA-mediated defense that is similar to posttranscriptional gene silencing (PTGS) of transgenes. Here we demonstrate with potato virus X (PVX) that PTGS operates as a systemic, sequence-specific defense system. However, in grafting experiments or with movement defective forms of PVX, we could not detect systemic silencing unless the 25 kDa viral movement protein (p25) was made nonfunctional. Investigation of p25 revealed two branches to the PTGS pathway that converge in the production of 25 nucleotide RNAs corresponding to the target RNA. One of these branches is unique to virus-induced PTGS and is not affected by p25. The second branch is common to both virus- and transgene-induced PTGS, is blocked by p25, and is likely to generate the systemic silencing signal.
Voinnet
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O
The Sainsbury Laboratory, John Innes Centre, Norwich, United Kingdom.
Lederer
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C
Baulcombe
D C
DC
D017353:Gene Deletion; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D015967:Gene Expression Regulation, Viral / Q000502:physiology; D020868:Gene Silencing / Q000502:physiology*; D009154:Mutation / Q000235:genetics; D053830:Plant Viral Movement Proteins; D030821:Plants, Genetically Modified / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D010947:Plants, Toxic; D017863:Potexvirus / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism / Q000821:virology; D019076:Transgenes / Q000235:genetics; D014764:Viral Proteins / Q000235:genetics* / Q000378:metabolism
D053830:Plant Viral Movement Proteins; D018749:RNA, Plant; D012367:RNA, Viral; D014764:Viral Proteins