A site-specific deletion in mitochondrial DNA of Podospora is under the control of nuclear genes.

In the filamentous fungus Podospora anserina, the association of two nuclear genes inevitably leads to a "premature death" phenotype consisting of an early end of vegetative growth a few days after ascospore germination. Mycelia showing this phenotype contain a mitochondrial chromosome that always bears the same deletion. One of the break points is exactly at the 5' splice site of a particular mitochondrial intron, suggesting that the deletion event could result from molecular mechanisms also involved in intron mobility. One of the nuclear genes involved in triggering this site-specific event belongs to the mating-type minus haplotype; the other is a mutant allele of a gene encoding a cytosolic ribosomal protein. IMAGES: