Phylogeny and taxonomy of theOphiostoma piceaecomplex and the Dutch elm disease fungi

Abstract

The Ophiostoma piceae complex forms a monophyletic group of insect-dispersed pyrenomycetes with synnemata (Pesotum) and micronematous (Sporothrix) synanamorphs. Other species of Ophiostoma outside of the 0. piceae complex that form synnemata lack the Sporothrix state. The nine recognized species within the 0. piceae complex are delimited by synnema morphology, growth rate at 32 C, mating reactions and sequences of the internal transcribed spacer (ITS) region of the rDNA operon. Phylogenetic analysis of the ITS region suggests two major clades in the complex, one that causes bluestain in primarily coniferous hosts and the other on primarily hardwood hosts. In the coniferous group are 0. piceae, 0. canum, 0. floccosum and the recently described 0. setosum (anamorph Pesotum cupulatum sp. nov.). In the hardwood group are 0. querci, 0. catonianum, and the Dutch elm disease fungi: 0. ulmi, 0. novo-ulmi and 0. himal-ulmi. Restriction fragment length polymorphisms of the ITS region are shown to be a convenient diagnostic tool for delimiting these species.

Characterization of a Sapstaining Fungus,Ophiostoma floccosum, Isolated from the Sapwood ofPinus thunbergiiin Korea

“…5). It produced no culture aroma and no mycelium with concentric rings that were observed as distinguishing characteristics of O. floccosum by Harrington et al (2001). …”

“…Among these compared species reported from conifers, the characters of O. floccosum were most matched with those of DKM 0514. Especially, the red-brown synnema and yellow color of the conidia mass found in DKM 0514 were considered to be distinct features of O. floccosum by Harrington et al (2001). …”

“…O. floccosum (Mathiesen) Hunt (anamorph: Pesotum aureum (Hedgecock) McNew et Harrington), one of the common sapwood-staining species (Hunt, 1956; Harrington et al 2001), is known to have a Sporothrix type anamorph. Thus, we examined DKM 0514 to find it has a Sporothrix type anamorph.…”

“…More than ten Ophiostoma species have been classified in this complex group. Anamorphic stages of the species in the O. piceae complex resemble the anamorphs of Pesotum , Hyalorhinocladiella and Sporothrix with various morphological differences (Seifert et al, 1993; Wingfield et al, 1993; Harrington et al, 2001). Because they share similar morphological features and each species can have one or more of several anamorphs, it is not easy to differentiate the O. piceae complex species based only on morphological characters.…”

“…Because they share similar morphological features and each species can have one or more of several anamorphs, it is not easy to differentiate the O. piceae complex species based only on morphological characters. To assist in the differentiation of the O. piceae complex species, molecular methods including PCR and nucleotide sequence analysis of the ribosomal RNA gene and/or the β-tubulin genes have been used (Kim et al, 1999; Uzunovic et al, 2000; Harington et al, 2001; Chung et al, 2006). …”