title: Effects of a petunia scaffold/matrix attachment region on copy number dependency and stability of transgene expression in Nicotiana tabacum.
abstract: Transgenes in genetically modified plants are often not reliably expressed during development or in subsequent generations. Transcriptional gene silencing (TGS) as well as post-transcriptional gene silencing (PTGS) have been shown to occur in transgenic plants depending on integration pattern, copy number and integration site. In an effort to reduce position effects, to prevent read-through transcription and to provide a more accessible chromatin structure, a P35S-ß-glucuronidase (P35S-gus) transgene flanked by a scaffold/matrix attachment region from petunia (Petun-SAR), was introduced in Nicotiana tabacum plants by Agrobacterium tumefaciens mediated transformation. It was found that Petun-SAR mediates enhanced expression and copy number dependency up to 2 gene copies, but did not prevent gene silencing in transformants with multiple and rearranged gene copies. However, in contrast to the non-SAR transformants where silencing was irreversible and proceeded during long-term vegetative propagation and in progeny plants, gus expression in Petun-SAR plants was re-established in the course of development. Gene silencing was not necessarily accompanied by DNA methylation, while the gus transgene could still be expressed despite considerable CG methylation within the coding region.
authors.affiliation: Institute for Biosafety in Plant Biotechnology, Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Messeweg 11-12, 38104, Braunschweig, Germany. antje.dietz@jki.bund.de.
authors.forename: Antje
authors.initials: A
authors.lastname: Dietz-Pfeilstetter
authors.affiliation: Institute for Biosafety in Plant Biotechnology, Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Messeweg 11-12, 38104, Braunschweig, Germany.
authors.forename: Nicola
authors.initials: N
authors.lastname: Arndt
authors.affiliation: Institute for Biosafety in Plant Biotechnology, Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Messeweg 11-12, 38104, Braunschweig, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Manske
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics; D018628:Gene Dosage; D015870:Gene Expression; D020868:Gene Silencing; D005966:Glucuronidase / Q000096:biosynthesis / Q000235:genetics*; D045170:Matrix Attachment Regions / Q000235:genetics; D032306:Petunia / Q000235:genetics; D030821:Plants, Genetically Modified / Q000235:genetics*; D011401:Promoter Regions, Genetic; D014026:Nicotiana / Q000235:genetics*; D019076:Transgenes / Q000235:genetics
chemical_list: D005966:Glucuronidase
keywords: DNA methylation; Gene expression; Matrix attachment region; Petunia; Transgene silencing