CORRELATION BETWEEN CHITIN DISTRIBUTION AND CELL-WALL MORPHOLOGY IN THE MYCORRHIZAL FUNGUS GLOMUS-VERSIFORME

The distribution of N-acetylglucosamine residues in the cell wall of Glomus versiforme was studied by using fluorescein- and gold-labelled wheat germ agglutinin (WGA). This lectin is considered to possess specific binding sites for GlcNAc and a strong affinity for its oligomers and polymers, especially chitin. The affinity techniques provide a spatial description of the occurrence of the sugar residues. Chitin always occurred in the cell walls of the fungus studied throughout the whole duration of its symbiotic development. Gold granules conjugated with wheat germ agglutinin were found both on the thick walls of extraradical and intraradical hyphae as well as on the thin walls of arbuscular branches, irrespective of wall texture which was fibrillar or amorphous. However, when the fluorescein-labelled lectin was used, only the thin arbuscular branches were labelled. These observations lead to the conclusion that the probe accessibility to the substrate changes on the in toto hyphae and on the thin sections and that the thick-walled hyphae have their chitin partially hidden by non-chitinous cell wall components. These components were soluble to heat treatment alkali and oxidizing agent. © 1990, British Mycological Society. All rights reserved.