Environmental Factors Can Influence Mitochondrial Inheritance in the Saccharomyces Yeast Hybrids

Abstract

Mitochondria play a critical role in the generation of metabolic energy and are crucial for eukaryotic cell survival and proliferation. In most sexual eukaryotes, mitochondrial DNA (mtDNA) is inherited from only one parent in non-Mendelian inheritance in contrast to the inheritance of nuclear DNA. The model organism Saccharomyces cerevisiae is commonly used to study mitochondrial biology. It has two mating types: MATa and MATα. Previous studies have suggested that the mtDNA inheritance patterns in hybrid diploid cells depend on the genetic background of parental strains. However, the underlying mechanisms remain unclear. To elucidate the mechanisms, we examined the effects of environmental factors on the mtDNA inheritance patterns in hybrids obtained by crossing S. cerevisiae with its close relative S. paradoxus. The results demonstrated that environmental factors can influence mtDNA transmission in hybrid diploids, and that the inheritance patterns are strain dependent. The fitness competition assay results showed that the fitness differences can explain the mtDNA inheritance patterns under specific conditions. However, in this study, we found that fitness differences cannot fully be explained by mitochondrial activity in hybrids under stress conditions.

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

“…in warm glucose-based media) to construct crosses, rather than a respiratory media, on which we almost exclusively observed S. cerevisiae mtDNA inheritance. There may be a strong strain dependence of mtDNA inheritance, a phenomenon also suggested by other groups (Solieri et al 2008;Albertin et al 2013) and supported by a recent study of mtDNA inheritance in crosses of S. cerevisiae and Saccharomyces paradoxus where both YPD and YP + glycerol were used as carbon source (Hsu and Chou 2017). Here they found that crossing one pair of S. cerevisiae and S. paradoxus strains in YPD (with 2 % glucose, as with our study) and YP + glycerol resulted in the retention of mtDNA from the S. cerevisiae parent, whilst crossing an alternative pair (different strains) of S. cerevisiae and S. paradoxus) resulted in the retention of mtDNA from the S. paradoxus parent, regardless of carbon source.…”

“…For example, S. cerevisiae has eight origins of replication whilst S. uvarum has four (Masneuf et al 1998). However, this would fail to explain major differences seen between S. cerevisiae and S. paradoxus and different Saccharomyces strains of the same species (Hsu and Chou 2017). Furthermore, it is unclear which mechanisms may be acting on mtDNA selection associated with temperature variation.…”

“…Researchers also found that fitness differences between S. cerevisiae × S. paradoxus mitotypes explained the inheritance of mtDNA in some conditions and not others, but that effects also varied depending on the strains used (Hsu and Chou 2017). Regardless of the factors affecting inheritance, the retention of S. cerevisiae mtDNA is evidently advantageous to hybrids growing in warm temperatures and particularly so in respiratory conditions, where mitochondrial function is essential.…”

Population Analysis and Evolution of Saccharomyces cerevisiae Mitogenomes

“…When dividing between mother cell and bud, mitochondria rely on complex network actions in order to distribute the organelles evenly across the cells [31][32][33]. Replication and partitioning of the mitochondrion is not related to the cell cycle, depending instead on the replication and expression of its own genes and nuclear-encoded proteins [10,34]. For mitochondrial biogenesis, both nuclear and mitochondrially encoded components are required [10].…”

“…Replication and partitioning of the mitochondrion is not related to the cell cycle, depending instead on the replication and expression of its own genes and nuclear-encoded proteins [10,34]. For mitochondrial biogenesis, both nuclear and mitochondrially encoded components are required [10]. Since the mitogenome encodes a small subset of proteins, it requires the ones encoded in the nucleus in order to express its genome [35].…”