Source: CropBiotech Update

Co-existence mapped for Bt, conventional maize

Most markets allow a 0.9% threshold of adventitious presence for genetically modified (GM) organisms. At what distance should GM crops be planted from conventional ones to keep within the threshold? In “Pollen-mediated gene flow in maize in real situations of coexistence”, Joaquima Messeguer and colleagues from various research institutions in Barcelona and Girona, Spain conduct the first study on cross-fertilization between Bt and conventional maize in real situations of coexistence in two regions in which Bt and conventional maize were cultivated. Their findings appear in the latest issue of Plant Biotechnology.

Scientists sampled maize from transgenic fields and analyzed them for the presence of GM DNA using the real-time quantification system-polymerase chain reaction (RTQ-PCR) technique. Researchers found that:

1) in general, the rate of cross-fertilization between GM and conventional plants was higher in the borders, with decreasing rates toward the center of the field;

2) In real conditions of coexistence and in cropping areas with smaller fields, the main factors that determined cross-pollination were the synchronicity of flowering and the distances between the donor and receptor fields;

3) By establishing an index on the two variables, a distance of about 20 m would be sufficient to maintain the 0.9% threshold.

Read the abstract of the article at
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1467-7652.2006.00207.x

Subscribers to Plant Biotechnology can access the complete article through the same link.