ASSESSING THE RISKS OF WIND POLLINATION FROM FIELDS OF GENETICALLY-MODIFIED BRASSICA-NAPUS SSP OLEIFERA

Intensive research over the past 10 years has produced many genetically-modified lines of oilseed rape with market potential. Assessment of these lines in statutory trials prior to their release as cultivars is necessary, owing to concern over the likelihood of transgene escape from such crops. Here, we examine the movement of airborne pollen grains from oilseed rape fields and assess their capacity for long-range geneflow. Pollen dispersal from isolated rape fields was monitored over two seasons and related to the distribution of fields and 'feral' (domesticated plants growing outside cultivations) populations of the crop in Tayside and North East Fife regions of Scotland. Airborne pollen density declined with distance and at 360 m was 10% of that at the field margin. Pollen counts of 0-22 pollen grains m(3) were observed 1.5 km from source fields and apparently were sufficient in number to allow seed set on emasculated bait plants. Oilseed rape pollen has greater capacity for long-range dispersal than had been suggested by small-scale field trials. Mean separation of oilseed rape fields in the survey area was 410 m and the mean distance from 'feral' populations to commercial fields was 700 m. Sixty percent of 'feral' populations with more than 10 plants occurred downwind and within 2 km of an oilseed rape field. Provided that the flowering biology of genetically-modified oilseed rape does not differ from the conventional crop, these data suggest that transgene movement to non genetically-modified fields or 'feral' populations is likely following commercial release.