@article{halfhill_sutherland_moon_poppy_warwick_weissinger_rufty_raymer_stewart_2005, title={Growth, productivity, and competitiveness of introgressed weedy Brassica rapa hybrids selected for the presence of Bt cry1Ac and gfp transgenes}, volume={14}, ISSN={["1365-294X"]}, DOI={10.1111/j.1365-294X.2005.02649.x}, abstractNote={Concerns exist that transgenic crop x weed hybrid populations will be more vigorous and competitive with crops compared with the parental weed species. Hydroponic, glasshouse, and field experiments were performed to evaluate the effects of introgression of Bacillus thuringiensis (Bt) cry1Ac and green fluorescent protein (GFP) transgenes on hybrid productivity and competitiveness in four experimental Brassica rapa x transgenic Brassica napus hybrid generations (F1, BC1F1, BC2F1 and BC2F2). The average vegetative growth and nitrogen (N) use efficiency of transgenic hybrid generations grown under high N hydroponic conditions were lower than that of the weed parent (Brassica rapa, AA, 2n = 20), but similar to the transgenic crop parent, oilseed rape (Brassica napus, AACC, 2n = 38). No generational differences were detected under low N conditions. In two noncompetitive glasshouse experiments, both transgenic and nontransgenic BC2F2 hybrids had on average less vegetative growth and seed production than B. rapa. In two high intraspecific competition field experiments with varied herbivore pressure, BC2F2 hybrids produced less vegetative dry weight than B. rapa. The competitive ability of transgenic and nontransgenic BC2F2 hybrids against a neighbouring crop species were quantified in competition experiments that assayed wheat (Triticum aestivum) yield reductions under agronomic field conditions. The hybrids were the least competitive with wheat compared with parental Brassica competitors, although differences between transgenic and nontransgenic hybrids varied with location. Hybridization, with or without transgene introgression, resulted in less productive and competitive populations.}, number={10}, journal={MOLECULAR ECOLOGY}, author={Halfhill, MD and Sutherland, JP and Moon, HS and Poppy, GM and Warwick, SI and Weissinger, AK and Rufty, TW and Raymer, PL and Stewart, CN}, year={2005}, month={Sep}, pages={3177–3189} }
 @article{halfhill_zhu bin_raymer_millwood_weissinger_stewart_2004, title={Hybridization and backcrossing between transgenic oilseed rape and two related weed species under field conditions}, volume={3}, ISBN={1635-7922}, DOI={10.1051/ebr:2004007}, abstractNote={Determining the frequency of crop-wild transgene flow under field conditions is a necessity for the development of regulatory strategies to manage transgenic hybrids. Gene flow of green fluorescent protein (GFP) and Bacillus thuringiensis (Bt) transgenes was quantified in three field experiments using eleven independent transformed Brassica napus L. lines and the wild relatives, B. rapa L. and Raphanus raphanistrum L. Under a high crop to wild relative ratio (600:1), hybridization frequency with B. rapa differed among the individual transformed B. napus lines (ranging from ca. 4% to 22%), however, this difference could be caused by the insertion events or other factors, e.g., differences in the hybridization frequencies among the B. rapa plants. The average hybridization frequency over all transformed lines was close to 10%. No hybridization with R. raphanistrum was detected. Under a lower crop to wild relative ratio (180:1), hybridization frequency with B. rapa was consistent among the transformed B. napus lines at ca. 2%. Interspecific hybridization was higher when B. rapa occurred within the B. napus plot (ca. 37.2%) compared with plot margins (ca. 5.2%). No significant differences were detected among marginal plants grown at 1, 2, and 3 m from the field plot. Transgene backcrossing frequency between B. rapa and transgenic hybrids was determined in two field experiments in which the wild relative to transgenic hybrid ratio was 5-15 plants of B. rapa to 1 transgenic hybrid. As expected, ca. 50% of the seeds produced were transgenic backcrosses when the transgenic hybrid plants served as the maternal parent. When B. rapa plants served as the maternal parent, transgene backcrossing frequencies were 0.088% and 0.060%. Results show that transgene flow from many independent transformed lines of B. napus to B. rapa can occur under a range of field conditions, and that transgenic hybrids have a high potential to produce transgenic seeds in backcrosses.}, number={2}, journal={Environmental Biosafety Research}, author={Halfhill, M. D. and Zhu Bin, Warwick S. I. and Raymer, P. L. and Millwood, R. J. and Weissinger, A. K. and Stewart, C. N.}, year={2004}, pages={73} }
 @article{halfhill_millwood_weissinger_warwick_stewart_2003, title={Additive transgene expression and genetic introgression in multiple green-fluorescent protein transgenic crop x weed hybrid generations}, volume={107}, ISSN={["1432-2242"]}, DOI={10.1007/s00122-003-1397-7}, number={8}, journal={THEORETICAL AND APPLIED GENETICS}, author={Halfhill, MD and Millwood, RJ and Weissinger, AK and Warwick, SI and Stewart, CN}, year={2003}, month={Nov}, pages={1533–1540} }
 @article{richards_halfhill_millwood_stewart_2003, title={Quantitative GFP fluorescence as an indicator of recombinant protein synthesis in transgenic plants}, volume={22}, ISSN={["0721-7714"]}, DOI={10.1007/s00299-003-0638-1}, number={2}, journal={PLANT CELL REPORTS}, author={Richards, HA and Halfhill, MD and Millwood, RJ and Stewart, CN}, year={2003}, month={Sep}, pages={117–121} }
 @article{halfhill_millwood_rufty_weissinger_stewart_2003, title={Spatial and temporal patterns of green fluorescent protein (GFP) fluorescence during leaf canopy development in transgenic oilseed rape, Brassica napus L.}, volume={22}, ISSN={["1432-203X"]}, DOI={10.1007/s00299-003-0696-4}, number={5}, journal={PLANT CELL REPORTS}, author={Halfhill, MD and Millwood, RJ and Rufty, TW and Weissinger, AK and Stewart, CN}, year={2003}, month={Dec}, pages={338–343} }