“…Other immunocytochemical studies have shown the presence of plant-derived molecules in the extracellular material, including hydroxyproline-rich glycoproteins (Hippe-Sanwald et al, 1994), tomato PR-1b, unesterified pectin, and arabinogalactan proteins (J. P. Wubben, cited in Wubben et al, 1994). In addition, interfacial material between hyphae of the arbuscular mycorrhizal fungus Glomus versiforme and the host plasma membrane has been shown to contain a number of polymers typical of plant cell walls, including cellulose, pectin, hydroxyproline-rich glycoproteins, and rhamnogalacturonan I (Bonfante-Fasolo et al, 1990b, 1991Balestrini et al, 1994Balestrini et al, , 1996. Indeed in this system, the composition of the interfacial material correlated with that of the cell wall of the specific cell type infected in a number of plants (Balestrini et al, 1996), although the components were not associated into a functional cell wall (Bonfante-Fasolo et al, 1990b).…”