Risk assessment studies in the cultivation of transgenic barley

Molecular breeding is becoming a useful tool in the improvement of plants and plant-based raw materials. Risk assessment studies are needed for the safe commercial use of transgenic plants. Risk assessment for the cultivation of transgenic barley was performed in 1996 and repeated in a larger scale in 1997 in order to provide information on pollen-mediated dispersal of transgenes via cross-fertilization. A transgenic barley line carrying a marker gene coding for neomycin phospho-transferase II (nptII) was used as a pollen donor. For maximum resolution a cytoplasmically male-sterile barley line was utilized as recipient and the flow of nptII transgene was monitored at distances of 1, 2, 3, 6, 12, 25, 50 and 100 meters from the donor plots of 225 m2 and 2000 m2. In Finnish conditions, the cross-fertilization frequency was found to be low. In male-sterile recipient barley the seed-set was low. In normal male-fertile barley the cross-fertilization frequency varied from 0% to 7%, depending on weather conditions on the heading day. Furthermore, in male-sterile barley the cross-fertilization frequency diminished rapidly with distance and only a few seeds were found at distances of 50 and 100 m. The molecular biological analysis of male-sterile heads revealed that all the seeds at a distance of 1 m were transgenic, but only 3% of the distant seeds (50 m) were transgenic. Due to competing self-produced and non-transgenic background pollen the correspond-ing figure will be even lower in normal recipient barley.