ENGINEERED GENES IN WILD POPULATIONS - FITNESS OF WEED-CROP HYBRIDS OF RAPHANUS-SATIVUS

The transfer of engineered genes (transgenes) from crops to natural po pulations will depend first on mating between the crop and related wee ds and then upon the relative fitness of the weed-crop hybrid. While w eed-crop hybridization is known to occur readily under agricultural co nditions, almost nothing is known of the fitness of the hybrids produc ed. Therefore, we measured the relative fitness of weedy radishes and their sibling weed-crop hybrids under field conditions. Specifically, we compared germination success, time to first flowering, fruit produc tion, seed production, and frequency of transmission of the crop allel e to seed progeny. Hybrids showed significantly greater fruit and seed production, and equaled weeds in all other measured characters. Thus, in this experiment, the fitness of hybrids exceeded that of their wil d siblings. These results suggest that, in at least this system, neutr al or advantageous transgenes introduced into natural populations will tend to persist.