CORN GRAIN COMMERCIALIZED IN MEXICO AS A POTENTIAL DISPERSER OF TRANSGENIC EVENTS

Abstract

Preserving diversity of maize without transgenes would be possible so long as the sources of introgression and dispersion of modified genes are understood. The objective of this study was to analyze the presence of transgenes in maize grains and seeds marketed in Mexico, as they are considered potential dispersers of transgenic events. Forty samples of grains and seeds of hybrids commercialized in Mexico were collected from production plots or sold commercially from domestic and imported origin. Three hundred seeds per genotype were sown in the field and when they were in the V4-V5 stage of foliar development glyphosate was sprayed on them evaluating the effect 15 days later. Based on the Resistance Frequency (RF) and damage level, genotypes were selected to be evaluated with ELISA immunoassays for recombinant protein CP4/EPSPS detection and a DNA-based test for presence/absence of P35S of CaMV and TNOS of A. tumefaciens by qPCR. The samples that tested positive for the presence of P35S and TNOS were sent to the National Reference Center for Genetically Modified Organisms (CNRDOGM) for validation and detection of specific events of modified sequences contained in the positive samples. Four hybrids showed the highest resistance to glyphosate in the field (RF ≤ 0.26). In the ELISA and qPCR tests the grain samples of the Jabalí hybrid and imported were positive for transgenic introgression. The presence of the events MON89034, TC1507 and MON810 (< 0.1 % in each case) was confirmed in grain of the hybrid Jabalí, as well as the events MON89034, MON810, MON88017, NK603, TC1507, Bt11, GA21 and MIR162 (26.42, 2.3, 0.16, 18, > 10.0, 8.7, 0.78 and 4.8 %, respectively) in imported grain. The presence of specific events in commercialized grains was confirmed as a potential pathway for dispersal of transgenes to native maize, highlighting that these grains, both national and imported, are functional seeds, which retain their ability to develop and express recombinant proteins for glyphosate resistance.