Figure 1.
Establishment of the mycorrhizal symbiosis.
An AMF contacts the surface of a legume root, by producing swollen structures called hyphopodia (in yellow) (A). Evident defence reactions are not detectable, and the epidermal cells appear alive, with the nuclei visible as blue spots. Once inside the root, the AMF colonizes the inner cortical cells, producing highly branched structures called arbuscules. Notwithstanding the massive colonization, the plant cells remain alive (B). Pictures kindly provided by Andrea Genre and Mara Novero, University of Torino.