GENETIC-MAPPING OF TELOMERIC DNA-SEQUENCES IN THE MAIZE PATHOGEN COCHLIOBOLUS-HETEROSTROPHUS

Numerous polymorphic bands were observed when genomic DNA of Cochliobo lus heterostrophus was cut with restriction enzymes and hybridized wit h a telomere-specific probe. Bal31 digestion demonstrated that the maj ority of the bands were from the chromosome termini and thus constitut e telomeres. However, numerous hybridizing sequences in the strain B30 .A3.R.45 were Bal31 exonuclease-insensitive and thus located at least 600 bases internal to the chromosome ends. Segregation analysis of the polymorphic bands identified nine telomeres; seven were linked to oth er markers and thus permitted the proper orientation of linkage groups with respect to their chromosome ends. Three internal, telomere-homol ogous sequences, at least one of which may be subtelomeric, were also mapped.