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Meiotic crossovers are relocated to polymorphic regions across the Arabidopsis genome through an MSH2-dependent mismatch-repair pathway.
Meiotic crossovers reshuffle parental alleles and determine which traits are inherited together. Madec and colleagues demonstrate that, in Arabidopsis thaliana, sequence polymorphism between homologous chromosomes is itself a powerful determinant of where crossovers form.
Making use of unique genetic material, the authors managed to compare the same genomic regions when they were polymorphic or non-polymorphic. Polymorphic regions recombined more frequently across the genome and could turn normally cold chromosome-end regions into crossover rich regions, at the expense of other regions of the chromosome. This redistribution depends on the mismatch-repair protein MSH2: without MSH2, crossovers are no longer preferentially directed toward polymorphic regions. The work identifies mismatch repair as a pro-crossover pathway in Arabidopsis and shows how local sequence divergence can extensively reorganize the genome-wide crossover landscape.
More information: https://doi.org/10.1038/s41467-026-76213-z
Contact: Chloé Girard chloe.girard@i2bc.paris-saclay.fr
