Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: August 27, 2001
Publication Date: N/A
Technical Abstract: Rhynchosporium secalis is the cause of scald disease of barley and rye. No teleomorph has been identified for R. secalis and its phylogenetic relationships are not known. To identify possible relatives of R. secalis, the 18S ribosomal RNA (rRNA) gene and internal transcribed spacer (ITS) region (ITS1, 5.8S rRNA gene, ITS2) were sequenced and compared to those of fother fungi obtained from databases. Analysis of 18S sequences identified no close relatives with known teleomorphs, but did place R. secalis within the Discomycetes. Neighbor joining trees from 73 aligned ITS sequences clustered R. secalis together with Phialophora gregata and other species with no known teleomorphs, many of which are endophytes or presumed endophytes. The closest relatives of R. secalis with known teleomorphs were species of Tapesia (anamorph Ramulispora (syn. Pseudocercosporella)), the cause of eyespot disease of cereals, and Pyrenopeziza (anamorph Cylindrosporium), the cause of light leaf spot on Brassica. Both of these are in the family Mollisiaceae, order Helotiales. Thus, the ascocarp of R. secalis, if it exists, most likely is a small, Tapesia like apothecium.