Role ofcis,trans, and inbreeding effects on meiotic recombination inSaccharomyces cerevisiae

Abstract

15Meiotic recombination is a major driver of genome evolution by creating new genetic combinations. 16To probe the factors driving variability of meiotic recombination, we used a high-throughput method 17 to measure recombination rates in 26 S. cerevisiae strains from different geographic origins and 18 habitats. Fourteen intervals were monitored for each strain, covering chromosomes VI and XI entirely, 19and part of chromosome I. We found an average number of crossovers per chromosome ranging 20 between 1.0 and 9.5 across strains ("domesticated" or not), which is higher than the average 21 between 0.5 and 1.5 found in most organisms. In the different intervals analyzed, recombination 22showed up to 9-fold variation across strains but global recombination landscapes along 23 chromosomes varied less. We also built an incomplete diallel experiment to measure recombination 24 rates in one region of chromosome XI in 10 different crosses involving five parental strains. Our 25overall results indicate that recombination rate is increasingly positively correlated with sequence 26. CC-BY 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/361428 doi: bioRxiv preprint first posted online Jul. 3, 2018; 2 similarity between homologs (i) in DSB rich regions within intervals, (ii) in entire intervals, and (iii) at 27 the whole genome scale. Therefore, these correlations cannot be explained by cis-effects only. In 28 addition, by using a quantitative genetics analysis, we identified an inbreeding effect that reduces 29 recombination rate in homozygous genotypes while other interaction effects (specific combining 30 ability) or additive effects (general combining ability) are found to be weak. Finally, we measured 31 significant crossover interference in some strains, and interference intensity was positively correlated 32 with crossover number. 44Using a high throughput method based on fluorescent markers, we investigated the diversity of 45 recombination in the budding yeast Saccharomyces cerevisiae. We observed up to 9-fold differences 46 in numbers of crossovers across hybrids obtained by crossing different strains with a common tester, 47and this variation was correlated with the degree of DNA sequence similarity between homologous 48 chromosomes. By also investigating homozygotes, we conclude that on the one hand too much 49 sequence divergence impairs recombination in distantly-related hybrids, and on the other hand 50 complete homozygosity is also associated with lower numbers of crossovers.

Loss of heterozygosity results in rapid but variable genome homogenization across yeast genetic backgrounds

“…The difference in the size of the events may be indicative of the specific underlying mechanisms. Moreover, meiotic spore fertility and recombination fidelity show a positive correlation in laboratory intraspecific S. cerevisiae hybrids (48).…”