Temporal dynamics of detected transgenes in maize landraces in their center of origin

Abstract

The first report of transgenic maize in Mexico was published in 2001 for Oaxaca, Mexico. Subsequent studies were controversial, because most of the maize samples analyzed from different years and localities, were negative. The purpose of this paper is to publish records of the presence of transgenic maize in Priority Terrestrial Regions in Oaxaca, and to contribute to the understanding of the movement of transgenic maize through seed management practices. During 2008-2018, 66 municipalities and 148 localities, belonging to 3 PTRs were monitored. A total of 1,210 farmers were surveyed on practices associated with maize management, and 1,412 maize samples were obtained and analyzed using molecular methods. Adventitious presence of transgenic sequences was detected in 1.69% of the samples. The positive samples came from municipalities belonging to Sierra Juárez, Los Loxicha region, and Santa María Huatulco. Farmers’ responses indicated that there is a high movement of seed among localities, but also from other areas of the country. Transgenes appear and disappear, indicating a highly dynamic spatio-temporal replacement over time, mainly due to introduction of foreign material. This aspect must be taken into account to regulate introduction of improved maize to traditional communities.