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Last Document: 3.1.1  Officially validated identification methods

Table of Contents  Foods derived from genetically modified organisms and detection methods

Next Document: 3.1.3  Highly specialised reports on the detection of GMOs in food unavailable in databases

3.1.2 Methods developed to detect GMOs and published in scientific journals

The first method for GMO identification in food stuffs was specifically developed to identify the Flavr Savr tomato (Meyer, 1995a). Relatively few articles have been written on the detection of approved genetically engineered plant products and published in specialised peer-reviewed journals. The PCR-based method developed for the Flavr Savr tomato has been applied already in food control laboratories in Germany, such as the 'Chemische Landesuntersuchungsanstalt' in Freiburg (Annual report CLUA, 1995; Pietsch and Waiblinger, 1996; Pietsch et al., 1997; Waiblinger et al., 1997), and in Switzerland by the 'Kantonales Laboratorium' in Basel-Stadt (personal communications, P. Brodmann, Kantonales Laboratorium Basel; Waiblinger et al., 1997). The amplified DNA fragment is 427 basepairs in size ( Primer sequences and amplicon length in PCR-assays to detect GMOs) and contains the interface between one of the transgenes (antisense polygalacturonase gene construct) and the promoter used to regulate this gene (P-35S promoter from cauliflower mosaic virus). For verification of the amplification product described in this method, agarose gel electrophoresis in combination with restriction enzyme analysis was employed.

For many of the genetically modified plants that have been developed (see  Field trials Table 1 and Figure 1), PCR assays have been used to confirm or control the success of plant transformation and thus can be found in many articles describing the generation of a transgenic plant. However, due to the large number of transformed plants it is almost impossible to provide a comprehensive compilation of these publications. A selection of articles describing PCR assays employing primers specific for genetic elements which have been used for the generation of currently approved genetically engineered agricultural crops is mentioned below. Some experimental details of the PCR assays such as primer length and sequence, location of primer binding sites, amplicon length and whether cycling parameters were described, are listed in  Primer sequences and amplicon length in PCR-assays to detect GMOs. The table contains references to publications on alfalfa (Blake et al., 1991), corn (Golovkin et al., 1993), papaya (Yang et al., 1996), potato (Jongedijk et al., 1992) and soybean (Padgette et al., 1995).

The following genetic elements (in general, only promoters, structural genes and terminators are mentioned) are described in the publications cited in Table 14: P-35S promoter from cauliflower mosaic virus (Jongedijk et al., 1992; Golovkin et al., 1993; Padgette et al., 1995), the gene coding for CP4 epsps (5-enolpyruvylshikimate-3-phosphate synthase from Agrobacterium sp., strain CP4) (Padgette et al., 1995), the gus (beta-glucuronidase) gene (Blake et al., 1991; Yang et al., 1996), the nptII (aminoglycoside-3'-phosphotransferase gene from transposon 5) gene (Blake et al., 1991) and the nos-terminator (Padgette et al., 1995), derived from the 3'-region of the nopaline synthase gene from Agrobacterium tumefaciens. With the exception of transgenic cotton from DuPont (ID 22) and rapeseed from Monsanto (ID 65), all of the approved genetically engineered agricultural crops have been transformed with constructs containing either the cauliflower mosaic virus 35S-promoter (P-35S) or its derivatives, the nos-terminator (nos 3') or both of these elements. These elements were derived from either a plant virus or from Agrobacterium, respectively.