Measuring gene flow from two birdsfoot trefoil (Lotus corniculatus) field trials using transgenes as tracer markers

Genetic engineering is becoming a useful tool in the improvement of plants but concern has been expressed about the potential environmental risks of releasing GM organisms into the environment. Attention has been focused on pollen dispersal as a major issue in the risk assessment of transgenic crop plants. In the present study, pollen-mediated dispersal of transgenes via cross-fertilization was examined. Plants of L. corniculatus L. transformed with either the E. coli asparagine synthetase gene asnA or the ƒÒ-glucuronidase gene uidA, were used as pollen donor. Non-transgenic plants belonging to the species L. corniculatus L., L. tenuis Waldst. and Kit. ex Willd, and L. pedunculatus Cav., were utilized as recipients. Two experimental fields were established in two areas of central Italy. Plants carrying the uidA gene were partially sterile, therefore only the asnA gene was used as tracer marker. No transgene flow between L. corniculatus transformants and the non-transgenic L. tenuis and L. pedunculatus plants was detected. As regards non-transgenic L. corniculatus plants, in one location the flow of asnA transgene was detected up to a distance of 18 m from the 1.8 m2 donor plot. In the other location, pollen dispersal occurred up to 120 m away from the 14 m2 pollinating plot