High-resolution mapping of meiotic crossovers and non-crossovers in yeast

Nature. 2008 Jul 24;454(7203):479-85. doi: 10.1038/nature07135. Epub 2008 Jul 9.

Abstract

Meiotic recombination has a central role in the evolution of sexually reproducing organisms. The two recombination outcomes, crossover and non-crossover, increase genetic diversity, but have the potential to homogenize alleles by gene conversion. Whereas crossover rates vary considerably across the genome, non-crossovers and gene conversions have only been identified in a handful of loci. To examine recombination genome wide and at high spatial resolution, we generated maps of crossovers, crossover-associated gene conversion and non-crossover gene conversion using dense genetic marker data collected from all four products of fifty-six yeast (Saccharomyces cerevisiae) meioses. Our maps reveal differences in the distributions of crossovers and non-crossovers, showing more regions where either crossovers or non-crossovers are favoured than expected by chance. Furthermore, we detect evidence for interference between crossovers and non-crossovers, a phenomenon previously only known to occur between crossovers. Up to 1% of the genome of each meiotic product is subject to gene conversion in a single meiosis, with detectable bias towards GC nucleotides. To our knowledge the maps represent the first high-resolution, genome-wide characterization of the multiple outcomes of recombination in any organism. In addition, because non-crossover hotspots create holes of reduced linkage within haplotype blocks, our results stress the need to incorporate non-crossovers into genetic linkage analysis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromosome Mapping*
  • Chromosomes, Fungal / genetics
  • Crossing Over, Genetic / genetics*
  • DNA Breaks, Double-Stranded
  • DNA-Binding Proteins / genetics
  • Flap Endonucleases
  • Gene Conversion / genetics*
  • Gene Expression Regulation, Fungal
  • Genetic Linkage / genetics
  • Genetic Markers / genetics
  • Genome, Fungal / genetics
  • Genotype
  • Haplotypes / genetics
  • Meiosis / genetics*
  • Mutation / genetics
  • Saccharomyces cerevisiae / cytology
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae Proteins / genetics
  • Trans-Activators / genetics

Substances

  • DNA-Binding Proteins
  • Genetic Markers
  • MSH4 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Trans-Activators
  • Flap Endonucleases
  • MMS4 protein, S cerevisiae