Major mitochondrial nuclease; has RNAse and DNA endo- and exonucleolytic activities; prevents genome instability by degrading extranuclear DNA sequences; roles in mitochondrial recombination, apoptosis and maintenance of polyploidy;  involved in fragmentation of genomic DNA during PND (programmed nuclear destruction); role in preventing L-A mycovirus pathogenesis; encodes ortholog of mammalian endoG