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QUANTIFICATION OF TRANSGENIC PLANT MARKER GENE PERSISTENCE IN THE FIELD
Citation:
Widmer, F., R. Seidler, K. K. Donegan, AND G. L. Reed. QUANTIFICATION OF TRANSGENIC PLANT MARKER GENE PERSISTENCE IN THE FIELD. Molecular Ecology 6(1):1-7, (1997).
Description:
Methods were developed to monitor persistence of genomic DNA in decaying plants in the field. As a model, we used recombinant neomycin phosphotransferase II (rNPT-II) marker genes present in genetically engineered plants. Polymerase chain reaction (PCR) primers were designed, complementary to 20-bp sequences of the nopaline synthase promoter in a transgenic tobacco and the cauliflower mosaic virus 35S promoter in a transgenic potato. The PCR reverse primer was complementary to a 20-bp sequence of the N-terminal NPT-II coding region. The PCR protocol allowed for quantification of as few as 10 rNPT-II genes per reaction. We analysed rNPT-II marker gene amounts in samples obtained from two field experiments performed at different locations in Oregon. In transgenic tobacco leaves, buried at 10 cm depth in a field plot in Corvallis, marker DNA amount dropped to 0.36% during the first 14 days and was detectable for 77 days at a final level of 0.06% of the initial amount. Monitoring of residual potato plant litter, from the soil surface of a test field in Hermiston, was performed for 137 days. After 84 days marker gene amounts dropped to 2.74% (leaf and stem) and 0.50% (tuber) of the initially detected amount. At the final sample date 1.98% (leaf and stem) and 0.19% (tuber) were detectable. These results represent the first quantitative analysis of plant DNA stability under field conditions and indicate that a proportion of the plant genomic DNA may persist in the field for several months.