Development and utilization of analytical methods for rapid GM detection in processed food products: a case study for regulatory requirement

Genetically modified (GM) food crops for desired traits have been approved in some of the countries. The approval status of a GM event varies from country to country. In India, Bt cotton is the only approved GM crop. So far, no GM food crop has got regulatory approval in the country, which may be considered as unauthorized GM (UGM) event in the Indian context. The entry of UGM events of food crops needs to be checked in the imported consignments as well as in the marketplace. In the present study, screening elements were identified based on the genetically modified organism (GMO) matrix developed as decision support system for 22 GM food crops approved globally. Three sets of multiplex PCR assays were developed and validated for GM detection in food crops and products: triplex PCR targeting control elements [Cauliflower Mosaic Virus 35S promoter (P-35S), Figwort Mosaic Virus promoter (P-FMV), nopaline synthase terminator (T-nos)], triplex PCR targeting marker genes [aminoglycoside-3’-adenyltransferase (aadA), neomycin phosphotransferase (nptII), phosphinothricin-N-acetyltransferase (pat)] and duplex PCR targeting Bt genes (cry1Ab/Ac and cry2Ab2). Limit of detection (LOD) ranged from 0.5–0.01% for different targets, which is in compliance with the labelling threshold of many countries. The developed assays were utilized to check the GM status of apple and maize products along with an additional test for ctp2-cp4epsps for herbicide tolerance in maize. Based on the tests conducted, none of these samples were found positive for GM targets screened. These procedures could be efficiently employed as a part of GMO testing to trace GM contamination, if any, in both the imported as well as domestic food products.