DNA sequence differences and temperature are determinants of meiotic recombination outcome

Meiotic recombination is essential for producing healthy gametes, and also generates genetic diversity. DNA double-strand break (DSB) formation is the initiating step of meiotic recombination, producing, among other outcomes, crossovers between homologous chromosomes, which provide physical links to guide accurate chromosome segregation. The parameters influencing DSB position and repair are thus crucial determinants of reproductive success and genetic diversity. Using Schizosaccharomyces pombe, we show that the distance between sequence polymorphisms across homologous chromosomes has a strong impact on recombination, not only locally as intragenic events, but also on crossover frequency. This effect is controlled by MutS-MutL factors and DNA helicases. Additionally, we establish temperature as a major factor modulating meiotic recombination frequency, and identify DSB processing as a temperature-sensitive step in the meiotic recombination pathway. This exposes a complex interplay of genetic and environmental parameters shaping the outcome of meiotic recombination.