Use of cloned DNA fragments as reference materials for event specific quantification of genetically modified organisms (GMOs)

For the quantification of genetically modified organisms (GMOs) in foods and feeds, real-time PCR is currently the most widely applied technique. To obtain a % of GMO, a GMO-specific target sequence is quantified relatively to a species-specific sequence. The correctness and reliability of the obtained quantitative results fully depend on the reference materials used as standards for setting up external calibration curves. We introduced a completely new type of standards for quantification of GMOs, based on cloned plasmid DNA solutions with well-known amounts of the sequences of interest, expressed as copy numbers. Moreover, the junction sequence between inserted DNA and plant DNA was used as 'unique identifier'. In this study, the model was applied for Roundup Ready soybean.