title: Cross-fertilization between genetically modified   and non-genetically modified maize crops in Uruguay.
abstract: The cultivation of genetically modified (GM) Bt maize (Zea mays L.) events MON810 and Bt11 is permitted in Uruguay. Local regulations specify that 10% of the crop should be a non-GM cultivar as refuge area for biodiversity, and the distance from other non-GM maize crops should be more than 250 m in order to avoid cross-pollination. However, the degree of cross-fertilization between maize crops in Uruguay is unknown. The level of adventitious presence of GM material in non-GM crops is a relevant issue for organic farming, in situ conservation of genetic resources and seed production. In the research reported here, the occurrence and frequency of cross-fertilization between commercial GM and non-GM maize crops in Uruguay was assessed. The methodology comprised field sampling and detection using DAS-ELISA and PCR. Five field-pair cases where GM maize crops were grown near non-GM maize crops were identified. These cases had the potential to cross-fertilize considering the distance between crops and the similarity of the sowing dates. Adventitious presence of GM material in the offspring of non-GM crops was found in three of the five cases. Adventitious presence of event MON810 or Bt11 in non-GM maize, which were distinguished using specific primers, matched the events in the putative sources of transgenic pollen. Percentages of transgenic seedlings in the offspring of the non-GM crops were estimated as 0.56%, 0.83% and 0.13% for three sampling sites with distances of respectively 40, 100 and 330 m from the GM crops. This is a first indication that adventitious presence of transgenes in non-GM maize crops will occur in Uruguay if isolation by distance and/or time is not provided. These findings contribute to the evaluation of the applicability of the "regulated coexistence policy" in Uruguay.
authors.affiliation: Departamento de Producción Vegetal, Centro Regional Sur, Facultad de Agronomía, Universidad de la República, Camino Folle km 36, Progreso, Canelones, Uruguay. pgaleano@fq.edu.uy
authors.forename: Pablo
authors.initials: P
authors.lastname: Galeano
authors.forename: Claudio Martínez
authors.initials: CM
authors.lastname: Debat
authors.forename: Fabiana
authors.initials: F
authors.lastname: Ruibal
authors.forename: Laura Franco
authors.initials: LF
authors.lastname: Fraguas
authors.forename: Guillermo A
authors.initials: GA
authors.lastname: Galván
mesh_terms: D051456:Gene Flow; D006824:Hybridization, Genetic; D030821:Plants, Genetically Modified; D019076:Transgenes; D014583:Uruguay; D003313:Zea mays / Q000235:genetics*