Mitochondrial recombination increases with age in Podospora anserina.
With uniparental inheritance of mitochondria, there seems little reason for homologous recombination in mitochondria, but the machinery for mitochondrial recombination is quite well-conserved in many eukaryote species. In fungi and yeasts heteroplasmons may be formed when strains fuse and transfer of organelles takes place, making it possible to study mitochondrial recombination when introduced mitochondria contain different markers. A survey of wild-type isolates from a local population of the filamentous fungus Podospora anserina for the presence of seven optional mitochondrial introns indicated that mitochondrial recombination does take place in nature. Moreover the recombination frequency appeared to be correlated with age: the more rapidly ageing fraction of the population had a significantly lower linkage disequilibrium indicating more recombination. Direct confrontation experiments with heterokaryon incompatible strains with different mitochondrial markers at different (relative) age confirmed that mitochondrial recombination increases with age. We propose that with increasing mitochondrial damage over time, mitochondrial recombination - even within a homoplasmic population of mitochondria - is a mechanism that may restore mitochondrial function.
Laboratory of Genetics, Plant Sciences, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
Anne D
AD
van Diepeningen
Daniël J
DJ
Goedbloed
S Marijke
SM
Slakhorst
A Bertha
AB
Koopmanschap
Marc F P M
MF
Maas
Rolf F
RF
Hoekstra
Alfons J M
AJ
Debets
D016922:Cellular Senescence / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D007438:Introns; D008928:Mitochondria / Q000235:genetics*; D048468:Podospora / Q000235:genetics / Q000502:physiology*; D011995:Recombination, Genetic
D004272:DNA, Mitochondrial