DYNACO · DYNAmics of CrossOver designation

Meiotic crossovers make us unique. Their distribution along chromosomes dictates which traits will be reassorted to create new and unique allele combinations on which selection can act. Early during meiosis, a large number of recombination interactions are initiated all across the genome, but only a few ultimately mature into crossovers. The final number and positions of crossovers are tightly regulated: along each chromosome, crossovers tend to be evenly spaced. This phenomenon, called crossover interference, was discovered in 1914 by Sturtevant and Morgan while drawing the first recombination map in flies. Emergence of spatial patterning requires communication. But how does the crossover formation machinery communicate with neighboring crossovers half a chromosome away? Our understanding of how this communication is established has been hindered by the limited resolution in time provided by classical cytology, giving us access to only snapshots of the process. In the DYNACO project, I will develop innovative solutions to explore the dynamics of crossover designation and interference. Using gentle live super-resolution microscopy combined with groundbreaking genetic and optogenetic tools in a very amenable system, the filamentous fungus Sordaria macrospora, I will address the following questions: (i) How do pro-crossover factors behave dynamically to enact and respond to crossover interference? (ii) What is the medium supporting crossover communication? (iii) What are the consequences of locally disrupting this communication?The DYNACO project will provide fundamental breakthroughs in our understanding of crossover formation, designation and interference. We will confront and reconcile many aspects of current models for crossover interference, and develop our own unified model. This work also has the potential to provide tools for the manipulation of recombination, to accelerate the introgression of selective traits into elite crop genomes.