Remodelling of crossover distribution induced by chromosome rearrangements in Arabidopsis.

Chromosome rearrangements including translocations, inversions and deletions can affect the crossover (CO) landscape. In Arabidopsis thaliana, we analyzed genome-wide recombination in a T-DNA mutant characterized by a reciprocal translocation involving chromosomes 3 and 4. We genotyped mutant and wild type segregating populations of 1680 plants using 143 SNPs homogenously genome distributed with an average interval length of 800 kb. Genotyping was performed using the patented KASP SNP detection system that uses Fluorescent Resonance Energy Transfer (FRET) probes on an arrayed 96 well plate. A wide region spanning 19,4 Mb of chromosome 3 (total length 24 Mb) exhibited suppressed recombination likely due to the translocation. Chromosome 4 (total length 17,7 Mb) showed a drop of CO number at a region of 3 Mb corresponding to the interchanged segment. However, the total number of COs/cell was not affected. Interestingly, the CO decrease on chromosome 3 is compensated by CO increase in the chromosomes 1, 2, and 5 thereby suggesting that CO homeostasis regulation occurs at cell level.