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

Area of Science:

• Agricultural Science
• Biotechnology
• Genetics

Background:

• Genetically modified (GM) Bt maize (events MON810 and Bt11) cultivation is permitted in Uruguay.
• Regulations mandate 10% non-GM refuge crops and >250m isolation distance to prevent cross-pollination.
• The extent of cross-fertilization between GM and non-GM maize in Uruguay was previously unknown.

Purpose of the Study:

• To assess the occurrence and frequency of cross-fertilization between commercial GM and non-GM maize crops in Uruguay.
• To determine the level of adventitious presence of GM material in non-GM crops, relevant for organic farming and seed production.

Main Methods:

• Field sampling of five GM and non-GM maize crop pairs with potential for cross-fertilization.
• Detection of adventitious GM material using DAS-ELISA and Polymerase Chain Reaction (PCR) with specific primers.
• Quantification of transgenic seedlings in non-GM crop offspring.

Main Results:

• Adventitious presence of GM material (MON810 or Bt11) was found in the offspring of non-GM crops in three out of five studied cases.
• Percentages of transgenic seedlings in non-GM offspring ranged from 0.13% to 0.83% at distances of 40m to 330m from GM crops.
• Cross-pollination occurred despite isolation distances, indicating potential transgene flow.

Conclusions:

• Adventitious presence of transgenes in non-GM maize crops is likely in Uruguay without strict adherence to isolation by distance and/or time.
• Findings highlight challenges for implementing "regulated coexistence policies" for GM and non-GM crops.
• This study provides crucial data for evaluating the practical application of coexistence strategies in Uruguayan agriculture.