The presence and levels of transgenic maize in Mexico and the effect this could have on local landraces or closely related species such as teosinte has been the subject of several previous reports, some showing contrasting results. Cultural, social and political factors all affect maize cultivation in Mexico and although since 1998 there has been a moratorium on the commercial cultivation of transgenic maize, Mexico imports maize, mainly from the USA where transgenic cultivars are widely grown. Additionally extensive migration between rural areas in Mexico and the USA and customs of seed exchange between farmers may also play an unintentional role in the establishment of transgenic seed. A comprehensive study of all Mexican maize landraces throughout the country is not feasible, however this report presents data based on analysis of 3204 maize accessions obtained from the central region of Mexico (where permits have never been authorized for cultivation of transgenic maize) and the northern region (where for a short period authorization for experimental plots was granted). The results of the study confirm that transgenes are present in all the geographical areas sampled and were more common in germplasm obtained in the northern region. However, there was no evidence that regions where field trials had been authorized showed higher levels of transgene presence or that the morphology of seed lots harboring transgenic material was significantly modified in favor of expected transgenic phenotypes.

墨西哥转基因玉米的存在和水平，以及它可能对当地品种或密切相关的物种（如大蜀黍）产生的影响，一直是之前几份报告的主题，其中一些报告显示了相反的结果。文化、社会和政治因素都会影响墨西哥的玉米种植，尽管自 1998 年起暂停了转基因玉米的商业种植，但墨西哥主要从广泛种植转基因品种的美国进口玉米。此外，墨西哥和美国农村地区之间的广泛迁移以及农民之间种子交换的习俗也可能在转基因种子的建立中发挥无意的作用。对全国所有墨西哥玉米地方品种进行全面研究是不可行的，但本报告提供的数据基于对从墨西哥中部地区（该地区从未获得种植转基因玉米的许可证）和北部地区获得的 3204 份玉米种质的分析。地区（授予短期试验田授权）。研究结果证实，转基因存在于所有采样的地理区域，并且在北部地区获得的种质中更为常见。然而，没有证据表明已授权进行田间试验的地区显示出较高水平的转基因存在，或者表明含有转基因材料的种子批的形态发生了显着改变，有利于预期的转基因表型。