| abstract |
The invention relates to methods and compositions for site-specific recombinase-mediated mobilization of viral replicons from T-DNA. The methods comprise Agrobacterium-mediated transfer of T-DNA to a plant cell, wherein the T-DNA contains a viral replicon flanked by directly repeated target sites for a site-specific recombinase and optionally a DNA of interest linked to the viral replicon. The DNA of interest may also contain a non-identical target site for the recombinase. An expression cassette for the site-specific recombinase is present on the T-DNA or the plant genome, or is transiently introduced into the plant cell. Expression of the site-specific recombinase in the plant cell results in excision of the viral replicon and the associated DNA of interest. The viral replicon and DNA of interest are then replicated to high copy number in the host plant cell. The compositions of the invention comprise nucleic acids, such as T-DNAs containing a viral DNA flanked by directly repeated target sites for a site-specific recombinase. The nucleic acids of the invention may additionally contain expression cassettes encoding the cognate site-specific recombinase for the target sites flanking the viral genome. The compositions of the invention further comprise Agrobacterium containing the nucleic acids of the invention. The compositions and methods of the invention have use in increasing the efficiency of agroinfection, providing high copy numbers of a DNA of interest for transient expression or for integration into a plant chromosome, and in simplifying the construction and stable maintenance of vectors for agroinfection and transformation. |