DIRECT COMPARISON OF POLLEN-MEDIATED MOVEMENT OF NATIVE AND ENGINEERED GENES

Despite the commercial approval of twenty-five transgenic crops in the U.S. as of mid-1996, concern is still being expressed regarding the p otential risks associated with genetically engineered crops. One recur ring issue is the possibility of pollen-mediated escape of engineered genes into populations of crop wild relatives. To address this concern , the scientific community has depended on literature on pollen disper sal generated from non-transgenic organisms. Utilization of this infor mation requires the assumption that the pollen mediated movement of na tive and transgenes is the same. To test the validity of this assumpti on, we directly compared the pollen-mediated gene movement of native a nd engineered marker genes using melon plants (Cucumis melo L.) expres sing dominant morphological and transgenic traits. Movement into both contiguous border plots and non-contiguous satellite plots were monito red. Dispersal of the native gene and transgene into the satellite plo ts was identical. Dispersal of the two traits into the plot borders wa s nearly identical. Of the nearly 4600 seedlings screened for both mor phological (presence of green vs. virescent cotyledons) and transgene movement (presence of NPT II protein by ELISA), in no case was the NPT II gene observed in the absence of green cotyledons. However, 39 seed lings were green but did not express NPT II as measured by ELISA. PCR analysis revealed transgene inactivation as a cause of the NPT II ELIS A(-) seedlings.