De novo methylation and co-suppression induced by a cytoplasmically replicating plant RNA virus.
The relationship between co-suppression and DNA methylation was explored in transgenic plants showing inducible co-suppression following infection with a cytoplasmically replicating RNA virus. Induction resulted in a loss of transgene mRNA and resistance to further infection, factors typical of post-transcriptional gene silencing. In infected plants, de novo methylation of the transgene appeared to precede the onset of resistance and only occurred in plants where the outcome was co-suppression. The methylation was limited to sequences homologous to the viral RNA and occurred at both symmetric and non-symmetric sites on the DNA. Although methylation is predicted to occur in mitotic cells, the virus was found not to access the meristem. A diffusible sequence-specific signal may account for the epigenetic changes in those tissues.
Jones
A L
AL
John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK.
Thomas
C L
CL
Maule
A J
AJ
D019175:DNA Methylation; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D017403:In Situ Hybridization; D018519:Meristem / Q000235:genetics; D009029:Mosaic Viruses / Q000235:genetics; D018532:Pisum sativum; D010942:Plant Viruses / Q000235:genetics*; D030821:Plants, Genetically Modified; D012328:RNA Viruses / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D012367:RNA, Viral / Q000235:genetics; D013489:Suppression, Genetic / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics
D012333:RNA, Messenger; D012367:RNA, Viral