INTRA-CHROMOSOMAL REARRANGEMENTS GENERATED BY CRE-LOX SITE-SPECIFIC RECOMBINATION

Chromosomal rearrangements are useful genetic and breeding tools but a re often difficult to detect and characterize. To more easily identify and define chromosome deletions and inversions, we have used the bact eriophage P1 Cre-lox site-specific recombination system to generate th ese events in plants. This involves three steps: (i) the introduction of two lox sites into one locus in a plant genome, including one site within a modified Os transposon; (ii) Ac transposase-mediated transpos ition of the Ds-lox element to a new locus on the same chromosome; (ii i) Cre-mediated site-specific recombination between the two lox sites that bracket a chromosome segment. We report the production of a delet ion and three inversion events in tobacco. The utility of chromosomal segments bracketed by lox sites for targeted manipulation and cloning is discussed.