Friday, March 25, 2011

Cross-fertilization study

Cross-fertilization between genetically modified and non-genetically
modified maize crops in Uruguay

By Galeano, Pablo a1a2 c1, Martínez Debat, Claudio a3, Ruibal, Fabiana a3,
Franco Fraguas, Laura a2 and Galván, Guillermo A. a1
Environmental Biosafety Research
DOI: 10.1051/ebr/2011100
Published online: March 25, 2011

a1 Departamento de Producción Vegetal, Centro Regional Sur (CRS),
Facultad de Agronomía, Universidad de la República, Camino Folle km 36,
Progreso, Canelones, Uruguay
a2 Cátedra de Bioquímica, Departamento de Biociencias, Facultad de
Química, Universidad de la República, General Flores 2124, Montevideo, Uruguay
a3 Sección Bioquímica, Instituto de Biología, Facultad de Ciencias,
Universidad de la República, Iguá 4225, Montevideo, Uruguay


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.

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