In Vivo Model Systems for Visualisation, Quantification and Experimental Studies of Intact Arbuscular Mycorrhizal Networks

In this chapter, the methods devised for the visualisation, in vivo monitoring and quantification of anastomosis formation in mycorrhizal networks formed by arbuscular mycorrhizal fungi are described. Anastomoses can be detected in hyphae originating from the same or different germlings and scored for compatible or incompatible responses. Successful anastomoses occur between hyphae belonging to the same or different individuals of the same isolate, whereas hyphae of individuals belonging to different genera, species and geographically different co-specific isolates are unable to fuse. The structure of extraradical networks growing from mycorrhizal roots can be studied by means of a bidimensional model system, allowing the assessment of growth rate, extent, viability and anastomosing ability of ex-novo-produced extraradical mycelium. This experimental model system has been also modified to show interconnections between mycorrhizal networks originating from different host plant species, genera and families, which can create immeasurably large numbers of fungal linkages within communities.