Homologous linear plasmids in mitochondria of three species of wheat bunt fungi, Tilletia caries, T. laevis and T. controversa

All isolates of Tilletia spp. investigated (five isolates of T. caries , including one from Japan, two isolates of T. laevis , and five isolates of T. controversa ) contained a linear DNA plasmid ranging in size from 7.2 to 7.6 kb. All plasmids were highly homologous to each other as shown by DNA-DNA hybridization and comparison of restriction enzyme sites. Variability in the size of the plasmid was found to be due to differences within a central region of the plasmid. No homology between the plasmid and mitochondrial or nuclear DNA was found.