Al Mouemar Anoir, Darmency Henri
Unité Mixte de Recherche sur la Biologie et la Gestion des Adventices, INRA, BP 86510, 21065 Dijon, France.
Environ Biosafety Res. 2004 Oct-Dec;3(4):209-14. doi: 10.1051/ebr:2005007.
Hybridization of Brassica napus L. (oilseed rape) and Raphanus raphanistrum L. (wild radish) has been demonstrated, and may be the first step towards introgression of transgenes in this wild relative. If wild radish were to display a new adaptive advantage by expressing the transgene, this could modify the ecological balance of species within the agro-ecosystem. To determine if transgenes remained stable in the hybrid, the frequency of herbicide resistance was studied over four advanced generations of hybrid progeny (G8 to G11) that were subjected to herbicide selection pressure. It is expected that hemizygous resistant plants containing an herbicide resistance transgene back-crossed to wild radish would have 50% resistant progeny. In each of the G8 to G11 generations, only 18% of the progeny from resistant plants were resistant. The chromosome complement of herbicide-susceptible progenies, analyzed at G9, was not different from that of wild populations of wild radish. Herbicide-resistant G9 progeny showed higher chromosome instability, and one third of the progeny contained a supernumerary chromosome. These results suggest that in the presence of herbicide selection pressure, the transgene for herbicide resistance would be maintained despite a lack of stabilized introgression. In the absence of selection, the frequency of resistance in the population is expected to decline.
甘蓝型油菜（Brassica napus L.）与野萝卜（Raphanus raphanistrum L.）的杂交已得到证实，这可能是将转基因导入该野生近缘种的第一步。如果野萝卜通过表达转基因展现出新的适应性优势，这可能会改变农业生态系统内物种的生态平衡。为了确定转基因在杂交种中是否保持稳定，对经过四代除草剂选择压力的杂交后代（G8至G11）的抗除草剂频率进行了研究。预计含有抗除草剂转基因的半合子抗性植株与野萝卜回交后，其后代中有50%具有抗性。在G8至G11的每一代中，抗性植株的后代只有18%具有抗性。在G9代分析的除草剂敏感后代的染色体组成与野萝卜野生种群的染色体组成没有差异。抗除草剂的G9代后代表现出更高的染色体不稳定性，三分之一的后代含有一条额外的染色体。这些结果表明，在存在除草剂选择压力的情况下，尽管没有稳定的基因渗入，抗除草剂转基因仍会得以保留。在没有选择的情况下，种群中的抗性频率预计会下降。
