Inversions in Plants – Detection, Mechanisms and Evolution

A growing number of international genome consortia have initiated large-scale sequencing projects for most of the major crop species. Their huge amounts of information not only boosted genetic and physical mapping research; they also created novel applications for chromosome biology. Here examples will be given of recent achievements in molecular cytogenetics tools that support plant genetics, genomics and breeding programs. The simultaneous detection of large number of BACs and smaller sized sequences by multicolour FISH now enables a rapid overview of supercontig and gap distribution on the euchromatic chromosome areas and displays directly and precisely the positions of chromosome rearrangements. The hybridization of BACs on the chromosomes of crops and their related species help confirm directly the genomic collinearity, or show inversions and translocations between their homeologues. This cross-species FISH together with meiotic pairing studies are powerful sources of information that elucidate the nature of the rearrangements, and the consequences of such a rearrangement for introgressive hybridizations. In addition, the outcome of detailed analysis of an inversion in the Columbia accession of Arabidopsis thaliana revealed the consequences of such a rearrangement for meiotic recombination, cytogenetic behaviour, DNA sequences of the inversion breakpoints and phylogeny of the inverted region.