School of Life Science, Shandong University, 27 Shanda South Road, Jinan 250100, PR China.
J Biotechnol. 2010 Jan 15;145(2):206-13. doi: 10.1016/j.jbiotec.2009.11.010. Epub 2009 Nov 20.
The possible release of selectable marker genes from genetically modified transgenic plants, or of gut microbes, to the environment, has raised worldwide public concerns. In this study, we showed the generation of marker-free transgenic maize plants constitutively expressing AtNHX1, a Na(+)/H(+) antiporter gene from Arabidopsis that conferred salt tolerance on plants, using the FLP/FRT site-specific recombination system. Transgenic plant expressing a modified FLP recombinase gene was crossed with transgenic plant harboring AtNHX1 and mutant als, a selectable marker gene flanked by two directed FRT sites. The sexual crossing led to precise and complete excision of the FRT-surrounded als marker gene in the F1 progenies. Further salt tolerance examinations indicated that marker-free AtNHX1 transgenic plants accumulated more Na(+) and K(+), and produced greater biomass and yields than did the wild-type plants when grown in high saline fields. These results demonstrate the feasibility of using this FLP/FRT-based marker elimination system to generate marker-free transgenic important cereal crops with improved salt tolerance.
从遗传修饰的转基因植物或肠道微生物中可能释放出可选择的标记基因到环境中，引起了全世界公众的关注。在这项研究中，我们利用 FLP/FRT 位点特异性重组系统，展示了无标记转基因玉米植株的产生，这些植株组成型表达拟南芥的 Na(+)/H(+)反向转运蛋白基因 AtNHX1，该基因赋予植物耐盐性。表达修饰的 FLP 重组酶基因的转基因植物与携带 AtNHX1 和突变 als 的转基因植物杂交，als 是一个由两个定向 FRT 位点包围的可选择标记基因。有性杂交导致 F1 后代中 FRT 周围 als 标记基因的精确和完全切除。进一步的耐盐性测试表明，与野生型植物相比，无标记 AtNHX1 转基因植物在高盐田生长时积累更多的 Na(+)和 K(+)，产生更大的生物量和产量。这些结果表明，利用这种基于 FLP/FRT 的标记消除系统来产生具有改良耐盐性的无标记重要谷物作物转基因是可行的。
