QUANTIFICATION OF GENETICALLY MODIFIED MAIZE WITH qPCR AND dPCR TECHNIQUES

In 2009 in Mexico, permission was given to release genetically modified maize (Zea mays L.) into the environment. This made it necessary to detect, identify and quantify genetically modified organisms (GMO) in the country's crops. The objective of this study was to validate the technique of absolute quantification of leaf mixtures in mass fraction of GM maize using real time (qPCR) and digital (dPCR) polymerase chain reaction (PCR) technique.Mixed leaves of maize modified with the MON810 event were prepared with conventional maize and analyzed with the qPCR technique. A certified reference plasmid and DNA obtained from a leaf with the MON810 modification were used as calibrants; besides, the dPCR technique was utilized since it allows a precise measurement of the number of DNA initial copies in the samples and does not require the utilization of calibrants. The test in qPCR complied with validation criteria, such as quantification limit, dynamic interval, amplification efficiency, correlation coefficient and estimation of uncertainty. Moreover, the dPCR technique was validated prior to quantification of the mixtures with the certified reference materials (CRM). Once the dPCR technique was validated, the GM material in the mixtures were quantified, and the results of the two techniques were comparable, indicating that they can be applied in quantifying genetic modification in crops and emit the results in mass fraction or copy number. The results show that quantification of genetically modified crop material in Mexico is possible with reliable results.