Location of cell-wall components in ectomycorrhizae of Corylus avellana and Tuber magnatum

The cell-wall components in ectomycorrhizae of Corylus avellana and Tuber magnatum have been investigated by using immunocytochemistry and enzyme/lectin-gold techniques. Observations were performed in differentiated regions of hazel roots in the presence and absence of the ectomycorrhizal fungus. The results provided new information on the location of specific components in both the host and the fungal wall. The cellobiohydrolase I (CBH I)-gold complex and the monoclonal antibody (MAb) CCRC-M1 revealed cellulose and xyloglucans, respectively, in the host wall. MAb JIM 5, which detected un-esterified pectins, labelled only the material occurring at the junctions between three cells, while no labelling was found after treatment with MAb JIM 7, which detected methyl-esterified pectins. MAb CCRC-M7, which recognized an arabinosylated beta-(1,6)-galactan epitope, weakly labelled tissue sections. MAb MAC 266, which detects a carbohydrate epitope on membrane and soluble glycoproteins, labelled the wall domain adjacent to the plasmamembrane. In the presence of the fungus, host walls were swollen and sometimes degraded. The labelling pattern of uninfected tissue was maintained, but abundant distribution of gold granules was found after CBH I and JIM 5 labelling. None of the probes labelled the cementing electron-dense material between the hyphae in the fungal mantle and in the Hartig net. The probes for fungal walls, i.e., wheat germ agglutinin (WGA) and concanavalin A (Con A) and a polyclonal antibody, revealed the presence of chitin, high-mannose side chains of glycoproteins and beta-1,3-glucans. Con A alone led to a labelling over the triangular electron-dense material, suggesting that this cementing material may contain a fungal wall component.