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ARS Home » Pacific West Area » Pullman, Washington » Plant Germplasm Introduction and Testing Research » Research » Publications at this Location » Publication #109771


item Dugan, Frank

Submitted to: Inoculum
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2000
Publication Date: 8/1/2000
Citation: Dugan, F.M. 2000. Synanamorphs of selenophoma species in culture. Inoculum. 51(3):27.

Interpretive Summary: Selenophoma (Pseudoseptoria) species are responsible for halo spot, a minor, seed-borne disease of grasses and cereals with economic impact on certain cereal cultivars. The existence of alternative states in culture has been superficially described for one species, S. donacis but extremely superficially and without attention to conideiogenesis. Sutton transferred graminicolous species of Selenophoma to Pseudoseptoria because of annellations on the conidigenous loci of herbarium specimens. Sutton and other workers have since noted Aureobasidium like synanamorphs on some of the species remaining in Selenophoma, but this abstract reports the same type of synanamorph on species transferred to Pseudoseptoria, and also reports that the annellations reported from herbarium material were not observed in culture.

Technical Abstract: Strains of Selenophoma (Pseudoseptoria) spp. were isolated from asymptomatic, surface-disinfested seeds and/or culms of Arrhenatherium, Bromus, Dactylis, Phalaris, and Pseudoroegneria species. Strains were grown on malt extract or half strength V8 agar and examined at 100-1000X with differential interference contrast. Cultures produced hyphomycetous synanamorphs commonly exhibiting synchronous conidia production typical for members of the Aureobasidium-Kabatiella complex. Elongated, micronematous conidiophores bore intercalary and terminal cells with 1-5 conidiogenous loci. Some isolates also produced conidiogenous cells in palisades on a stroma, and a minority of strains readily produced pycnidia similar to those described from the host. Yeast-like polar budding of 1- celled conidia, secondary conidia formation from multiple loci on septate conidia, and catenate conidia were common in most strains. Several strains produced two distinctive conidial morphologies: typical selenophomoid and irregularly vermiform. No annellations could be discerned on conidiogenous loci.