18S RIBOSOMAL-RNA GENE SEQUENCE CHARACTERS PLACE THE HUMAN PATHOGEN SPOROTHRIX-SCHENCKII IN THE GENUS OPHIOSTOMA

Using the sequence of the gene for the 18S subunit of ribosomal RNA, we show that the asexual human pathogenSporothrix schenckii lies phylogenetically within the sexual genusOphiostoma. By distance or maximum parsimony criteria,S. schenckii, Ophiostoma stenoceras, andO. ulmi (the Dutch elm disease fungus) are all related, butS. schenckii andO. stenoceras are more closely related to each other than either is toO. ulmi. the 18S RNA gene sequences ofS. schenckii andO. stenoceras are identical except at three sites, and the two species group together in 99% of the trees generated using the statistical method of bootstrapping. This is the first time that DNA sequence data have been used to place an asexual fungus, phylogenetically and with statistical support, in a sexual genus. © 1992 Academic Press, Inc.