Localization of beta (1-3) glucan in walls of the endomycorrhizal fungi Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe and Acaulospora laevis Gerd. & Trappe during colonization of host roots

Previous studies showed that cell walls of endomycorrhizal fungi belonging to the Acaulosporaceae and Glomaceae contain β(1-3) glucan polymers as well as chitin. Indirect immunolabelling with monoclonal and polyclonal antibodies has been used to investigate the distribution of these structural polysaccharides in cell walls of Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe and Acaulospora laevis Gerd. & Trappe as they interact with pea and tobacco roots, respectively. The β(1-3) glucans were detected in the walls of external hyphae, and of hyphal coils and intercellular hyphae developing in outer root tissues. The glucan component was alkali-insoluble but treatment with chitinase resulted in solubilization of most of the β(1-3) glucans from the fungal wall. A decrease in immunolabelling was associated with thinning out of the hyphal wall as the fungi colonized deeper in the host root, and β(1-3) glucans could not be detected in walls of intercellular hyphae or arbuscules in the parenchyma cortical tissue. The molecular configuration of cell walls of G. mosseae and A. laevis is discussed in relation to fungal morphogenesis and the symbiotic state in endomycorrhiza.