SEQUENCE SIMILARITY OF MATING-TYPE IDIOMORPHS - A METHOD WHICH DETECTS SIMILARITY AMONG THE SORDARIACEAE FAILS TO DETECT SIMILAR SEQUENCES IN OTHER FILAMENTOUS ASCOMYCETES

The hypothesis that genes encoding proteins which control sexual reproduction may be conserved among the filamentous ascomycetes was tested by hybridization of probes prepared from the open reading frames (mt A-1 and mt a-1) of the A and a mating type idiomorphs of Neurospora crassa to Southern blots containing genomic DNA isolated from seven species of filamentous ascomycetes. Both mating type-specific probes hybridized strongly to single copy sequences in Sordaria brevicollis and N. crassa only. These results indicate that the DNA sequences of these genes are not highly conserved among filamentous ascomycetes beyond the Sordariaceae. Therefore, if genes of equivalent molecular function exist in other filamentous ascomycetes then either their DNA sequences have diverged substantially or they evolved independently in several lineages.