Molecular evidence for the presence of Ophiosphaerella narmari n. comb., acause of spring dead spot of Bermuda grass, in North America

The phylogenetic relationships among fungi that cause spring dead spot dise ase of Bermuda grass in Australia and the United States were studied from n ucleotide sequence data of the ITS region of the rDNA. High levels of seque nce similarity were observed among Ophiosphaerella hepotricha, O. korrae an d Leptosphaeria narmari. These species clustered into a distinct clade that was distant from other Leptosphaeria and Phaeosphaeria species. Based on s equence data and previous descriptions of the ascoma and ascospore characte ristics of these species, we propose a taxonomic transfer of L. narmari to O. narmari. Oligonucleotide primers specific for O. narmari were developed from ITS1 and ITS2 regions to help identify non-sporulating isolates. These primers amplified all isolates of O. narmari, including those from the Uni ted States, hut not those of O. herpotricha, O. korrae or other ectotrophic root-inhabiting fungi. This is the first report of O. narmari in North Ame rica. Two Group I introns were found in the small subunit rDNA of some isol ates of O. korrae and O. narmari, but not O. herpotricha. A 425-nucleotide intron in O. narmari and O. korrae was inserted two nucleotides downstream from the ITS5 conserved primer sequence. These introns exhibited an 80% seq uence identity. In addition, a second 431-nucleotide intron in O. narmari w as similar in size and location to one in O. korrae.