External Seminar "Unlocking meiotic crossovers in plants" by Joiselle Fernandes

Unlocking meiotic crossovers in plants

Speaker: Joiselle Fernandes, Max Planck Institute in Cologne

Abstract: Meiotic crossovers enhance genetic diversity by shuffling the genome between homologous chromosomes. This produces novel combinations of alleles, which natural or artificial selection can then act upon, driving evolution and crop improvement. However, the number of crossovers is limited, at about one to three per chromosome pair in the majority of eukaryotes. Additionally, crossover distribution is not uniform along chromosomes, and is universally suppressed in centromere-proximal regions, creating a bottleneck in plant breeding.
During the seminar, I will discuss the factors that regulate crossover formation in Arabidopsis thaliana. We discovered that crossover number, hence allele shuffling, can be increased genome-wide when these factors are mutated. This effect is conserved in crops such as tomatoes, in which we also observed an increase in crossover number in the corresponding mutants.
However, although we increased crossovers genome-wide in these mutants, the crossovers remain suppressed closer to centromeres. Therefore, we designed a forward genetic screen that identified three genes which when mutated unlocked crossovers closer to centromeres.
Thus, manipulating crossovers has enabled us to access chromosomal regions which were previously inaccessible for plant breeding and crop improvement.