FANCM Limits Meiotic Crossovers in Brassica Crops.

Meiotic crossovers (COs) are essential for proper chromosome segregation and the reshuffling of alleles during meiosis. In WT plants, the number of COs is usually small, which limits the genetic variation that can be captured by plant breeding programs. Part of this limitation is imposed by proteins like FANCM, the inactivation of which results in a 3-fold increase in COs in . Whether the same holds true in crops needed to be established. In this study, we identified EMS induced mutations in FANCM in two species of economic relevance within the genus . We showed that CO frequencies were increased in mutants in both diploid and tetraploid and respectively. In , we observed a 3-fold increase in the number of COs, equal to the increase observed previously in . In we observed a lesser but consistent increase (1.3-fold) in both euploid (AACC) and allohaploid (AC) plants. Complementation tests in suggest that the smaller increase in crossover frequency observed in reflects residual activity of the mutant C copy of FANCM. Altogether our results indicate that the anti-CO activity of FANCM is conserved across the , opening new avenues to make a wider range of genetic diversity accessible to crop improvement.