title: Event-specific plasmid standards and real-time PCR methods for transgenic Bt11, Bt176, and GA21 maize and transgenic GT73 canola.
abstract: Since the 18th of April 2004, two new regulations, EC/1829/2003 on genetically modified food and feed products and EC/1830/2003 on traceability and labeling of GMOs, are in force in the EU. This new, comprehensive regulatory framework emphasizes the need of an adequate tracing system. Unique identifiers, such as the transgene genome junction region or a specific rearrangement within the transgene DNA, should form the basis of such a tracing system. In this study, we describe the development of event-specific tracing systems for transgenic maize lines Bt11, Bt176, and GA21 and for canola event GT73. Molecular characterization of the transgene loci enabled us to clone an event-specific sequence into a plasmid vector, to be used as a marker, and to develop line-specific primers. Primer specificity was tested through qualitative PCRs and dissociation curve analysis in SYBR Green I real-time PCRs. The primers were then combined with event-specific TaqMan probes in quantitative real-time PCRs. Calibration curves were set up both with genomic DNA samples and the newly synthesized plasmid DNA markers. It is shown that cloned plasmid GMO target sequences are perfectly suitable as unique identifiers and quantitative calibrators. Together with an event-specific primer pair and a highly specific TaqMan probe, the plasmid markers form crucial components of a unique and straighforward tracing system for Bt11, Bt176, and GA21 maize and GT73 canola events.
authors.affiliation: Department for Plant Genetics and Breeding, Centre for Agricultural Research, Caritasstraat 21, B-9090 Melle, Belgium. i.taverniers@clo.fgov.be
authors.forename: Isabel
authors.initials: I
authors.lastname: Taverniers
authors.forename: Pieter
authors.initials: P
authors.lastname: Windels
authors.forename: Marc
authors.initials: M
authors.lastname: Vaïtilingom
authors.forename: Anne
authors.initials: A
authors.lastname: Milcamps
authors.forename: Erik
authors.initials: E
authors.lastname: Van Bockstaele
authors.forename: Guy
authors.initials: G
authors.lastname: Van den Eede
authors.forename: Marc
authors.initials: M
authors.lastname: De Loose
mesh_terms: D001483:Base Sequence; D029741:Brassica rapa / Q000235:genetics*; D018744:DNA, Plant / Q000737:chemistry; D005819:Genetic Markers; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified / Q000235:genetics*; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D003313:Zea mays / Q000235:genetics*
chemical_list: D018744:DNA, Plant; D005819:Genetic Markers