Detection of cauliflower mosaic virus by the polymerase chain reaction: testing of food components for false-positive 35S-promoter screening results

Today DNA-based techniques are very common for the detection of genetically modified organisms (GMOs) in food products. For fast and easy detection of GMOs, polymerase chain reaction (PCR) screening methods, which amplify com mon transgenic elements, are applied in routine analysis. These techniques do not allow differentiation between GMOs and the natural occurrence of tra nsgenic elements, such as the 35S-promoter of cauliflower mosaic virus (CaM V) or the NOS-terminator of Agrobacterium tumefaciens, and thus may result in false-positive detection of GMOs. In this study we evaluated three diffe rent existing 35S screening systems and report the development of two new C aMV-specific PCR systems. These PCR systems based on CaMV-specific genes al low the identification of positively screened 35S food samples as naturally virus-infected products or plants. Seven food samples tested positive in r outine 35S screening analysis and negative in GMO specific systems were inv estigated using the new virus-specific PCR systems. In all seven samples Ca MV was detected.