title: Suppression of Virus Accumulation in Transgenic Plants Exhibiting Silencing of Nuclear Genes.
abstract: Homology-dependent gene silencing contributes to variation between transgenic plants with respect to transgene and/or endogenous gene expression levels. Recent studies have linked post-transcriptional gene silencing and virus resistance in plants expressing virus-derived transgenes. Using a potato virus X vector, we present three examples in which silencing of nonviral transgenes prevented virus accumulation. This effect was dependent on sequence homology between the virus and the silenced transgene. Analysis of potato virus X derivatives carrying bacterial [beta]-glucuronidase (GUS) sequences showed that the 3[prime] region of the GUS coding sequence was a target of the silencing mechanism in two independent tobacco lines. Methylation of the silenced GUS transgenes in these lines was also concentrated in the 3[prime] region of the GUS coding sequence. Based on this concurrence, we propose a link between the DNA-based transgene methylation and the RNA-based gene silencing process.
authors.affiliation: The Sainsbury Laboratory, John Innes Centre, Colney Lane, Norwich, NR4 7UH, United Kingdom.
authors.forename: J. J.
authors.initials: JJ
authors.lastname: English
authors.forename: E.
authors.initials: E
authors.lastname: Mueller
authors.forename: D. C.
authors.initials: DC
authors.lastname: Baulcombe