Pollen mediated transgene flow in lettuce (Lactuca sativa L.).

Transgene escape risks are evaluated by assessing the frequency of transgenic hybrids within populations sexually compatible with those genetically modified. We examined the pollen-mediated transgene flow among lettuce varieties in Italy. Transgenic 'Luxor' lines harboured the arabidopsis KNAT1, which caused leaf trait alterations, and the bacterial NPTII for resistance to kanamycin. Donor homozygous lines (KNAT1:NPTII/KNAT1:NPTII) were used in two trials: in glasshouse, 'Luxor' transgenic and conventional plants were spaced at 15cm; in field, a transgenic 'Luxor' donor island was set up and surrounded by ten pollen receiver varieties sited at 0.5, 11 and 22m. Progenies of recipient cultivars were screened by kanamycin assays, leaf alterations, transgene transcription and integrity. The out-crossing rate (OCR) was calculated as the frequency of KNAT1:NPTII/- and dKNAT1:NPTII/- genotypes because KNAT1 impair (indicated with d) was observed to vary from the 0.03 to 0.36%. Indoor, 'Luxor' intra-varietal OCR was 0.41±0.11%; outdoor, the average inter-varietal OCR was 0.49%, 0.071% and 0.035% for plants at 0.5, 11 and 22m, respectively.