A TRANSGENE-CENTERED APPROACH TO THE BIOSAFETY OF TRANSGENIC PHOSPHINOTHRICIN-TOLERANT PLANTS

The microbial bar and pat genes confer tolerance to the non-selective herbicide phosphinothricin (PPT; sold as Basta or Finale). This tolera nce in plants could provide an environmental gain compared to current- day herbicide cocktails, but the safety of such a transgene approach i s questioned by many. The biosafety of the presence of these herbicide tolerance genes in plants is evaluated in a 'transgene-centered appro ach'. Potentially, the introduction of transgenic PPT-tolerant crops c ould result in acquired PPT tolerance in weedy relatives of these crop s. Assuming responsible use of this trait in agronomy, the ecological consequences with respect to weediness or spread of the transgenic PPT tolerance are concluded to be negligible. The key issue for the toxic ological evaluation is whether or not the plant has actually been spra yed with PPT. Consumption of the gene and/or gene product from unspray ed transgenic plant material will not have adverse effects. In case of PPT-sprayed material, PPT or its derivatives could be present in food and feed and crop-specific metabolites might be formed. To date, the toxicological impact of such a putative exposure is not sufficiently c lear, and further premarket testing is recommended.