Quantification of pollen mediated gene flow in maize.

One approach to ensuring coexistence of genetically modified (GM) and conventional maize (Zea mays L.) is the understanding of pollen dispersal in order to keep GM-inputs below the regulated tolerance threshold of 0.9%. In defining science-based isolation distances between GM and non-GM maize fields, cross-fertilization rates have been studied both in experimental and commercial fields. Gene flow was followed based on Bt maize sequence information. Our results pointed out that cross- fertilization levels rapidly decrease with increasing distance from the pollen source and a 25 m isolation distance would be sufficient to keep GM-inputs from cross-fertilizations below the tolerance threshold of 0.9% in the harvest of neighboring non-GM maize fields.