THE CELL-WALL, AN ESSENTIAL COMPONENT OF THE ECTOMYCORRHIZAL SYMBIOSIS

Parietal interactions play an important role in the establishment and the functioning of the ectomycorrhizal symbiosis. During the initial p hase, glycofibrils emitted by the fungal wall link together hyphae to the root of the host-plant. The ''mycorrhizal infection zone'' is char acterized by a particular parietal composition with large amounts of a cid polysaccharides. In an established mycorrhiza, an interfacial stru cture adapted to exchanges appears between the two partners. Morphogen esis and structure of host and the fungus walls are modified, the surf ace of exchange being increased by wall ingrowths in the host and fals e septa in the fungus. In ectomycorrhizas, wall limits are blurred and partners are separated by a mixed apoplast.