New Multiplexing Tools for Reliable GMO Detection

Among the available methods for GMO detection, enforcement and routine laboratories use in practice PCR, based on the detection of transgenic DNA. The cost required for GMO analysis is constantly increasing due to the progress of GMO commercialization, with inclusion of higher diversity of species, traits and introduced genetic elements. Thus, analytical technologies must evolve towards high throughput GMO diagnostics. This chapter describes different strategies recently developed tosimultaneously detect/identify many GMOs. The combination of two or more PCR assays into one single tube is known as multiplexing. Multiplex PCRs combining a limited number of targets are available for GMO analysis. In some cases, several of these reactions can be performed in parallel and the resulting products mixed and detected together by capillary electrophoresis or array hybridization. Non PCR-based approaches (e.g. NAIMA) have also been explored for higher multiplexing potential. Simultaneous detection of very high numbers of targetsis possible bya SNPlex method based on single nucleotide polymorphisms and the Padlock ligation microarray system, relying on a first ligation that only occurs after hybridization to the target, followed by PCR and detection by array. Multiplex assays are most often qualitative, andif necessary, they can be coupled to specific simplex assays for quantification.Nevertheless, we discuss some strategies developed to achieve quantitative results with a multiplex approach.