Formation and Structure of Sclerotia and Sclerotium-Specific Proteins in Hygrophoropsis Aurantiaca

ABSTRACT

Hygrophoropsis aurantiaca is a widely occurring wood decay basidiomycete. The material presented represents the first report of Sclerotium production by isolates of this fungus in axenic culture. Anatomy of sclerotia and influence of certain nutritional factors on Sclerotium production have been investigated. In liquid culture H. aurantiaca grew on a variety of nitrogen sources, but generally failed to produce sclerotia. Likewise, C:N ratio affected growth and colony morphology in liquid culture but failed to induce sclerotia. A significant effect of C:N ratio on Sclerotium number was observed with solid media containing glucose and ammonium chloride, with optimal production at C:N ratios of 2.0-3.5. Sclerotia consisted of a distinct melanized rind and a pseudoparenchymatous medulla. Medullary cells contained glycogen and numerous protein bodies. One dimensional SDS Polyacrylamide gel electrophoresis revealed presence of sclerotium-specific proteins. Molecular weight estimates of major sclerotium-specific proteins were similar to those reported for other basidiomycetes and lower than reported values for ascomycetes. Future investigations of sclerotium-specific proteins may contribute to our understanding of the taxonomic placement of this fungus.

Key Words:

• Hygrophoropsis aurantiaca
• sclerotia
• C:N ratio
• nitrogen source
• sclerotium-specific protein