Understanding cell wall re-modelling during mycorrhizal symbiotic interactions

Ectomycorrhizal (ECM) fungi have a small set of genes coding for secreted enzymes putatively involved in the degradation of plant cell wall polysaccharides. Within the context of the Tuber melanosporum genome sequencing, genes coding for putative plant cell wall degrading enzymes (CWDE) have been identifed, and several of them were found to be up-regulated during symbiosis, suggesting a role in plant cell wall degradation to facilitate the progression of the hyphae in the pectin-rich middle lamella, when the fungus develops inside plant tissues. Looking at the arbuscular mycorrhizal (AM) fungi, Rizophagus irregularis does not possess degrading enzymes acting on plant cell walls, suggesting that signal molecules released by AM fungi are perceived by the plant cells, which elicit the activation of their own PCW-degrading enzymes. In addition to gene expression analyses, we have employed glycan microarray technology to analyse the impact of fungal colonization on plant cell wall composition in ecto- and AM mycorrhizae. In situ immunolabelling experiments, using monoclonal antibodies with specifcity for plant cell-wall components, are ongoing with the aim to support glycoarray data