National Research Council Associate, 200 SW 35th Street, Corvallis, OR 97333, USA.
Ann Bot. 2010 Dec;106(6):957-65. doi: 10.1093/aob/mcq190. Epub 2010 Sep 18.
With the advent of transgenic crops, genetically modified, herbicide-resistant Brassica napus has become a model system for examining the risks and potential ecological consequences of escape of transgenes from cultivation into wild compatible species. Escaped transgenic feral B. napus and hybrids with compatible weedy species have been identified outside of agriculture and without the apparent selection for herbicide resistance. However, herbicide (glyphosate) exposure can extend beyond crop field boundaries, and a drift-level of herbicide could function as a selective agent contributing to increased persistence of transgenes in the environment.
The effects of a drift level (0·1 × the field application rate) of glyphosate herbicide and varied levels of plant competition were examined on plant fitness-associated traits and gene flow in a simulated field plot, common garden experiment. Plants included transgenic, glyphosate-resistant B. napus, its weedy ancestor B. rapa, and hybrid and advanced generations derived from them.
The results of this experiment demonstrate reductions in reproductive fitness for non-transgenic genotypes and a contrasting increase in plant fitness for transgenic genotypes as a result of glyphosate-drift treatments. Results also suggest that a drift level of glyphosate spray may influence the movement of transgenes among transgenic crops and weeds and alter the processes of hybridization and introgression in non-agronomic habitats by impacting flowering phenology and pollen availability within the community.
The results of this study demonstrate the potential for persistence of glyphosate resistance transgenes in weedy plant communities due to the effect of glyphosate spray drift on plant fitness. Additionally, glyphosate drift has the potential to change the gene-flow dynamics between compatible transgenic crops and weeds, simultaneously reducing direct introgression into weedy species while contributing to an increase in the transgenic seed bank.
随着转基因作物的出现，经过基因改造、能抗除草剂的油菜已成为一个模型系统，用于研究转基因从栽培逃逸到野生亲缘种的风险和潜在生态后果。在农业之外已经发现了逃逸的转基因野生油菜和与杂草种杂交的油菜，并且没有明显的抗除草剂选择。然而，除草剂（草甘膦）的暴露范围可能超出农田边界，而草甘膦的漂流水平可能作为一种选择剂，有助于增加环境中转基因的持久性。
在模拟田间小区、普通花园实验中，我们研究了漂流水平（田间施用量的 0.1 倍）的草甘膦除草剂和不同水平的植物竞争对与植物适应性相关的性状和基因流的影响。所包括的植物有转基因、抗草甘膦的油菜、其野生祖先油菜，以及由它们衍生的杂种和后代。
该实验的结果表明，非转基因基因型的生殖适应性降低，而转基因基因型的植物适应性增加，这是由于草甘膦漂流处理的结果。结果还表明，草甘膦喷雾的漂流水平可能会影响转基因作物和杂草之间的转基因转移，并通过影响群落内的开花物候和花粉可获得性来改变非农业生境中的杂交和基因渗入过程。
本研究的结果表明，由于草甘膦喷雾漂移对植物适应性的影响，草甘膦抗性转基因在杂草植物群落中可能具有持久性。此外，草甘膦漂移有可能改变兼容的转基因作物和杂草之间的基因流动态，同时减少直接基因渗入杂草种，同时增加转基因种子库。
