Plasticity of Mitochondrial DNA Inheritance and its Impact on Nuclear Gene Transcription in Yeast Hybrids

Mitochondrial DNA (mtDNA) in budding yeast is biparentally inherited, but colonies rapidly lose one type of parental mtDNA, becoming homoplasmic. Therefore, hybrids between different yeast species possess two homologous nuclear genomes, but only one type of mitochondrial DNA. We hypothesise that the choice of mtDNA retention is influenced by its contribution to hybrid fitness in different environments, and that the allelic expression of the two nuclear sub-genomes is affected by the presence of different mtDNAs in hybrids. Here, we crossed Saccharomyces cerevisiae with S. uvarum under different environmental conditions and examined the plasticity of the retention of mtDNA in each hybrid.