Site-Specific Cassette Exchange in Plant by SDI(Site-Direct-Integration) System

Abstract:

We developed a site-direct-integration (SDI) system for Agrobacterium-mediated transformation to introduce a single copy of desired genes into a previously designated locus by gene replacement. This system consists a target vector to introduce the target (nptII, codA) genes into tobacco plants and an exchange vector to subsequently introduce the desired (hpt, luc) genes into transgenic plants that have a single copy of the target genes. Both the target and desired genes are flanked by two oppositely oriented recombination (RS) sites for exchange. The ipt, recombinase (R) and desired genes of an exchange vector are flanked by two directly oriented RS sites. Recombinase catalyzes an exchange of target genes for desired genes and removal of randomly integrated copies of desired genes. Transgenic plants with only an exchanged copy are selected as a normal phenotype by the ipt gene. Here we show that the SDI system can be used to efficiently replace target genes in a plant genome with desired genes and produce transgenic plants (T0) with an exchanged copy in a homozygous condition, and may be a useful method to engineer crop plants.