title: Generation of marker-free transgenic maize with improved salt tolerance using the FLP/FRT recombination system.
abstract: 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.
authors.affiliation: School of Life Science, Shandong University, 27 Shanda South Road, Jinan 250100, PR China.
authors.forename: Bei
authors.initials: B
authors.lastname: Li
authors.forename: Ning
authors.initials: N
authors.lastname: Li
authors.forename: Xiaoguang
authors.initials: X
authors.lastname: Duan
authors.forename: Aiying
authors.initials: A
authors.lastname: Wei
authors.forename: Aifang
authors.initials: A
authors.lastname: Yang
authors.forename: Juren
authors.initials: J
authors.lastname: Zhang
mesh_terms: D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D024861:Genetic Enhancement / Q000379:methods*; D018869:Heat-Shock Response / Q000502:physiology*; D030821:Plants, Genetically Modified / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D045522:Recombinases / Q000235:genetics / Q000378:metabolism*; D055051:Salt-Tolerant Plants / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D003313:Zea mays / Q000502:physiology*
chemical_list: D029681:Arabidopsis Proteins; C507998:FLP protein, Arabidopsis; D011994:Recombinant Proteins; D045522:Recombinases; D014157:Transcription Factors