PLASTICITY OF THE MITOCHONDRIAL GENOME IN PODOSPORA - POLYMORPHISM FOR 15 OPTIONAL SEQUENCES - GROUP-I, GROUP-II INTRONS, INTRONIC ORFS ANDAN INTERGENIC REGION

The mitochondrial chromosome of 15 Podospora anserina and one Podospor a comata wild-type strains have been extensively examined for the pres ence of optional elements and for sequence divergence. Among the P. an serina strains, nine optional sequences were found. By comparing P. an serina with the closely related and weakly interfertile P. comata spec ies, six additional optional sequences were detected. These optional e lements correspond to mitochondrial introns belonging to different gro ups and subgroups (11 cases), intronic open reading frames (two cases) , a complex insert and an intergenic region. Although difficult to exp lain, the distribution of optional mitochondrial sequences among the 1 5 wild-type isolates of P. anserina is far from random.