Despite mtDNA polymorphism the mobile intron (plDNA) of the COI gene is present in ten different races of Podospora anserina

Summary Polymorphism of mitochondrial DNA (mtDNA) from ten different geographical races of Podospora anserina was characterized by means of restriction and hybridization analysis. Our data reveals that the mobile intron (plDNA), first characterized by DNA sequencing in strain s (Osiewacz and Esser 1984), is present in all of the races investigated. Therefore, we conclude that the mobile intron is not an optional intron of the COI gene in wild type strains. In addition, the detailed physical and genetical mapping of mtDNA from three different races with different lifespans leads us to propose that length polymorphism can result due to the lack or presence of intron sequences of structural mitochondrial genes. In view of our results we discuss the function of the mobile intron during senescence in P. anserina.