The mismatch repair system contributes to meiotic sterility in an interspecific yeast hybrid

EMBO J. 1996 Apr 1;15(7):1726-33.


The mismatch repair system is the major barrier to genetic recombination during interspecific sexual conjugation in prokaryotes. The existence of this anti-recombination activity has implications for theories of evolution and the isolation of species. To determine if this phenomenon occurs in eukaryotes, the effect of a deficiency of mismatch repair on the meiotic sterility of an interspecific hybrid of Saccharomyces cerevisiae and the closely related species Saccharomyces paradoxus was examined. The results demonstrate that the rare viable spores from these hybrids have high frequencies of aneuploidy and low frequencies of genetic exchange. Hybrids lacking mismatch repair genes PMS1 or MSH2 display increased meiotic recombination, decreased chromosome non-disjunction and improved spore viability. These observations are consistent with the proposal that the mismatch repair system is an element of the genetic barrier between eukaryotic species. We suggest that an anti-recombination activity during meiosis contributes towards the establishment of post-zygotic species barriers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aneuploidy
  • Carrier Proteins*
  • Conjugation, Genetic
  • Crossing Over, Genetic
  • DNA Repair / genetics*
  • DNA-Binding Proteins / genetics
  • Fungal Proteins / genetics
  • Hybridization, Genetic
  • Meiosis / genetics*
  • Models, Genetic
  • MutL Proteins
  • MutS Homolog 2 Protein
  • Recombination, Genetic
  • Saccharomyces / genetics*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins*
  • Species Specificity
  • Spores, Fungal / genetics


  • Carrier Proteins
  • DNA-Binding Proteins
  • Fungal Proteins
  • PMS1 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • MSH2 protein, S cerevisiae
  • MutL Proteins
  • MutS Homolog 2 Protein