01/03 - Emilien Peltier (ISVV) : Inheritance, Phenotypic Variation, And Missing Heritability Hidden Behind The Mitochondrial Genome

In the yeast species S. cerevisiae, mitochondrial transmission is biparental. The cross of two parental strains generates a heteroplasmic cell containing both parental mitochondrial genomes (mtDNA) and after few vegetative divisions only one mitochondrial genome is retained, leading to homoplasmy. Therefore, the transmitted mtDNA can be either from one of the two parents or can also be a recombined genome from the two parentals DNA. Potential bias in transmission toward specific mitotype or the level of recombination was never explored at the species level.

This aspect was investigated by selecting twenty parental strains representative of the S. cerevisiae population and by the analysis of the mitochondrial DNA transmission of their 190 possible pairwise cross. A Bulk whole genome sequencing approach was used to follow mtDNA transmission in large progeny unveiling transmission deviation at the whole genome level or at the gene level. The pairwise experimental design allowed to see if these deviations were cross or strain specific and to rank mitotypes or haplotypes according to their fitness. Intron content was found to be a major factor impacting mtDNA transmission through intron homing mechanism. Intron homing efficiency according to intron and cross was analyzed and revealed strong interaction between introns. Altogether these results shed light on the factors impacting mtDNA transmission at the species level in S. cerevisiae.