title: Measuring gene flow in the cultivation of transgenic cotton (Gossypium hirsutum L.).
abstract: Transgenic Bt cotton NewCott 33B and transgenic tfd A cotton TFD were chosen to evaluate pollen dispersal frequency and distance of transgenic cotton (Gossypium hirsutum L.) in the Huanghe Valley Cotton-producing Zone, China. The objective was to evaluate the efficacy of biosafety procedures used to reduce pollen movement. A field test plot of transgenic cotton (6 x 6 m) was planted in the middle of a nontransgenic field measuring 210 x 210 m. The results indicated that the pollen of Bt cotton or tfd A cotton could be dispersed into the environment. Out-crossing was highest within the central test plot where progeny from nontransgenic plants, immediately adjacent to transgenic plants, had resistant plant progeny at frequencies up to 10.48%. Dispersal frequency decreased significantly and exponentially as dispersal distance increased. The flow frequency and distance of tfd A and Bt genes were similar, but the pollen-mediated gene flow of tfd A cotton was higher and further to the transgenic block than that of Bt cotton (chi2 = 11.712, 1 degree of freedom, p < 0.001). For the tfd A gene, out-crossing ranged from 10.13% at 1 m to 0.04% at 50 m from the transgenic plants. For the Bt gene, out-crossing ranged from 8.16% at 1 m to 0.08% at 20 m from the transgenic plants. These data were fit to a power curve model: y = 10.1321x-1.4133 with a correlation coefficient of 0.999, and y = 8.0031x-1.483 with a correlation coefficient of 0.998, respectively. In this experiment, the farthest distance of pollen dispersal from transgenic cotton was 50 m. These results indicate that a 60-m buffer zone would serve to limit dispersal of transgenic pollen from small-scale field tests.
authors.affiliation: The Institute of Environmental and Human Health, and Department of Environmental Toxicology, Texas Technical University, Lubbock, TX 79409, USA. baohong.zhang@ttu.edu
authors.forename: Bao-Hong
authors.initials: BH
authors.lastname: Zhang
authors.forename: Xiao-Ping
authors.initials: XP
authors.lastname: Pan
authors.forename: Teng-Long
authors.initials: TL
authors.lastname: Guo
authors.forename: Qing-Lian
authors.initials: QL
authors.lastname: Wang
authors.forename: Todd A
authors.initials: TA
authors.lastname: Anderson
mesh_terms: D000383:Agriculture; D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics; D002681:China; D017343:Genes, Plant; D003368:Gossypium / Q000235:genetics*; D006540:Herbicides; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified; D011058:Pollen / Q000235:genetics; D014170:Transformation, Genetic
chemical_list: D006540:Herbicides