Data from: Genome dynamics of hybrid Saccharomyces cerevisiae during vegetative and meiotic divisions

Mutation and recombination are the major sources of genetic diversity in
all organisms. In the baker's yeast, all mutation rate estimates are
in homozygous background. We determined the extent of genetic change
through mutation and loss of heterozygosity (LOH) in a heterozygous
Saccharomyces cerevisiae genome during successive vegetative and meiotic
divisions. We measured genome wide LOH and base mutation rates during
vegetative and meiotic divisions in a hybrid (S288c/YJM789) S. cerevisiae
strain. The S288c/YJM789 hybrid showed nearly complete reduction in
heterozygosity within 31 generations of meioses and improved spore
viability. LOH in the meiotic lines was driven primarily by the mating of
spores within the tetrad. The S288c/YJM789 hybrid lines propagated
vegetatively for the same duration as the meiotic lines, showed variable
LOH (from 2-3% and up to 35%). Two of the vegetative lines with extensive
LOH, showed frequent and large internal LOH tracts that suggest a high
frequency of recombination repair. These results suggest significant LOH
can occur in the S288c/YJM789 hybrid during vegetative propagation
presumably due to return to growth events. The average base substitution
rates for the vegetative lines (1.82 x 10-10 per base per division) and
the meiotic lines (1.22 x 10-10 per base per division), are the first
genome wide mutation rate estimates for a hybrid yeast. This study
therefore provides a novel context for the analysis of mutation rates
(especially in the context of detecting LOH during vegetative divisions),
compared to previous mutation accumulation studies in yeast that used
homozygous backgrounds.