Adhesion and development of the root rot fungus (Heterobasidion annosum) on conifer tissues: effects of spore and host surface constituents

• Published in: FEMS microbiology ecology Vol. 33; no. 2; pp. 101 - 110
• Main Author: Asiegbu, Frederick O.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.08.2000; Blackwell; Oxford University Press
• Subjects: Adhesion; Aliphatic compounds; Arabinose; Biological and medical sciences; Correlation analysis; Desiccation; Ecology; Fatty acid; Fatty acids; Freezing; Fructose; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Fungi; Germination; Glucose; Heterobasidion annosum; High performance liquid chromatography; Hyphae; Liquid chromatography; Mannitol; Mannose; Microbiology; NMR; Nuclear magnetic resonance; Oxidation; Oxidative stress; Pathology, epidemiology, host-fungus relationships. Damages, economic importance; Phytopathology. Animal pests. Plant and forest protection; Picea abies; Pine trees; Pinus sylvestris; Pretreatment; Root rot; Roots; Spore germination; Spores; Sugar; Sugar residue; Trehalose; Viability; Xylitol; Xylose; Spore germination; Sugar residue; Fatty acid; Plant pathogen; Heterobasidion annosum; Root; Germination; Basidiomycetes; Host agent relation; Pinus sylvestris; Fatty acids; Adhesion; Spores; Fungi; Pathogenicity; Infectivity; Softwood forest tree; Wood destroying fungi; Gymnospermae; Hypha; Coniferales; Spermatophyta; Carbohydrate; Picea abies; Colonization; Thallophyta
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2000.tb00732.x

Abstract The objective of this study was to correlate the occurrence of particular root and woody stump surface components with the ability of spores of the root rot fungus (Heterobasidion annosum) to adhere, germinate and establish on conifer tissues. With the aid of high performance liquid chromatography, several sugars (pinitol, xylitol, dulcitol, mannitol, d-glucose, mannose, fructose) were detected on both stump and fine root surfaces of Scots pine and Norway spruce. Of all the sugars observed, xylose and arabinose were poorly utilized for initiation of germ tube growth whereas spore germination was enhanced in the presence of d-glucose, mannose or fructose. Oxidation of these sugars by pretreatment of wood discs or roots with periodic acid abolished the ability of the spores to germinate. Non-sugar components such as long chain fatty acids on spores and root surfaces as detected with nuclear magnetic resonance were found to have a significant influence on adhesion and initiation of germ tube development. Removal of these aliphatic compounds from the root surface increased spore germination by 2-fold, whereas similar treatment on spores led to a 5-fold decrease in adhesiveness to root material. In vitro studies revealed that the di-ethyl ether extract from the roots had no long term adverse effect on spore germination which suggests that the fungus may possess the capability to detoxify this substance. Similarly, adhesion of spores was affected by low and freezing temperatures. The role of significant levels of mannitol and trehalose accumulated in spores and hyphae of the fungi on viability, survival and tolerance to adverse conditions such as oxidative stress, freezing and desiccation are discussed.