Arbuscular Mycorrhizal Fungi (AMF) are known to form with plants one of the most widespread symbiotic partnerships in nature. Unable to uptake carbon necessary to their own growth, AMF colonize roots to benefit from the large amount of carbon collected by a plant. In exchange for this vital supply, AMF bring to their host a large amount of nutrients such as nitrogen and phosphorus. AMF build complex networks made of filamentous hyphae of diameter ~ 10 μm that are able to expand and reach large spatial extents (> 1 m). Such dense and complex networks represent stocks of carbons and nutrients in soils where constant exchanges, which occur inside the hyphae through cytoplasmic streaming, bring resources both toward and away from host plants.
We describe the in-vitro culture of AMF in a symbiotic relationship with a growing root. We will first discuss the growth dynamics of such symbiotic networks. By visualizing and measuring flows within living symbiotic fungal networks, we characterize and quantify the transport of nutrients within a complex network. Our measurements document a wide diversity of intriguing intracellular flows able to sustain cooperative trades between AMF and the host plant. Finally, we will discuss how the flow dynamics is affected by the network topology.