COMPARATIVE PHYSICAL MAPPING GENUS ARABIDOPSIS INDICATES CHROMOSOMAL REARRANGEMENTS AROUND THE FLC LOCUS.

¹ Dept of Agronomy, Purdue University, West Lafayette, IN - 47907

An 880-kb contiguous region of the short arm of Arabidopsis thaliana chromosome 5, spanning the FLC locus, was chosen for comparative physical mapping in A. thaliana (2n=2x=10), A. arenosa (2n=4x=32), A. halleri (2n=2x=16) and A. neglecta (2n=16) using fluorescence in situ hybridization on DNA fibers (fiber-FISH). Bacterial artificial chromosome (BAC) clones representing this region were chosen from A. thaliana for mapping on DNA fibers of the chosen species. Fiber-FISH hybridization signals from A. halleri, A. neglecta, and A. arenosa species showed multiple gaps, indicating chromosomal insertion events in this region. Statistical analyses of measurements between A. thaliana and the other three species showed that most of the BAC regions in A. halleri, A. neglecta, and A. arenosa were 5 to 60% longer than A. thaliana. A histogram analysis of the measurement data suggested that some parts of the FLC region might be duplicated in several of the species. The comparative fiber-FISH mapping results indicate that chromosomal rearrangements have occurred around the FLC locus in the genomes of A. arenosa, A. halleri, and A. neglecta, and suggest a role for chromosomal duplication of parts of this region in the evolution of these species.