Transgenic corn in Mexico: From its center of origin to detection and monitoring techniques including a historical-cultural line of its use

Abstract Maize, as we know it today, underwent 9000 to 10,000 years of arduous natural selection by indigenous peoples in the Mesoamerican region. The modern maize cob evolved from a grass with an eight-seeded cob measuring only 3 mm. It now has multifilamentary kernels measuring up to 2 cm long and contains around 250 seeds. There is a vast diversity of maize races, and one classification suggests that there are more than 60 races in Mexico alone. In this work, we review the evolutionary and cultural background of maize in Mexico before opening the debate to question the current system of grain production and importation for direct human and animal consumption. Finally, we provide a comprehensive overview of methods for detecting and monitoring transgenic maize in various samples, ranging from grains to processed maize products such as flours, oils, and sweeteners. We also describe the theoretical foundations of these methods to enable effective testing that can be validated by any Mexican authority, in line with international standards, from sample collection to reporting results. DNA-based techniques, such as endpoint or real-time PCR, are used to validate a detection result in moderately specialized laboratories. Conversely, rapid preliminary techniques that are independent of DNA, such as those based on protein antigen-antibody ratios, are used in the field. However, over the past 10 years, the implementation of in situ DNA-based techniques has intensified. These methods are inexpensive, do not require sophisticated instruments, and are just as sensitive and specific as those routinely used in diagnostic laboratories. As corn originated in Mexico, the country needs all possible technology for the detection and monitoring of genetically modified organisms.