Patterns of below-ground plant interconnections established by means of arbuscular mycorrhizal networks

The ability of arbuscular mycorrhizal (AM) networks originating from plants of different species, genera and families to become interconnected by means of hyphal anastomoses was assessed. An in vivo two-dimensional experimental model system was used to reveal the occurrence of linkages between contiguous mycorrhizal networks spreading from Allium porrum root systems and those originating from Daucus carota, Gossypium hirsutum, Lactuca sativa, Solanum melongena, colonized by Glomus mosseae. Percentages of hyphal contacts leading to anastomosis between extraradical networks originating from different plant species ranged from 44% in the pairing A. porrum-S. melongena to 49% in A. porrum-G. hirsutum. DAPI and Sytox stainings detected nuclei in the middle of fusion bridges connecting different mycorrhizal networks. Present data suggest that, by means of anastomoses, AM fungal mycelium would potentially create an indefinitely large network interconnecting different plants in a community, and that, in the absence of sexual recombination, the intermingling of nuclei in extraradical mycelium may provide endless opportunities for the exchange of genetic material.