Elimination of mitochondrial mutations by sexual reproduction: two Podospora anserina mitochondrial mutants yield only wild-type progeny when mated.
In order to understand the transmission of mitochondrial mutations in sexual crosses of Podospora, we attempted to create compatible strains with defined mitochondrial mutations. A previously characterized mutant, Mn19, with a bipartite mitochondrial genome, served as the fertilizing parent in a cross with a mitochondrial deletion mutant, alphadelta5. Characterization of the deletion mutant is reported here. All six of the monokaryotic progeny isolated had neither parental defect but instead appeared to have inherited wild-type mitochondrial DNA. One of the progeny had a mitochondrial plasmid derived from intramolecular recombination between an 11-bp repeated mitochondrial sequence. Subsequent analysis using the polymerase chain reaction (PCR) identified rare undeleted wild-type mtDNA sequences in the maternal parent. The uniform inheritance of wild-type mitochondrial DNA suggests either an aggressive repair mechanism or else selective amplification and transmission of rare wild-type mtDNA molecules.
Silliker
M E
ME
Department of Biological Sciences, DePaul University, 1036 West Belden Avenue, Chicago IL 60614, USA.
Liotta
M R
MR
Cummings
D J
DJ
D000375:Aging; D001203:Ascomycota / Q000235:genetics* / Q000502:physiology; D001483:Base Sequence; D003433:Crosses, Genetic; D004272:DNA, Mitochondrial; D005784:Gene Amplification; D017353:Gene Deletion; D008928:Mitochondria / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D012098:Reproduction / Q000235:genetics
D004272:DNA, Mitochondrial