Inter-plant communication through mycorrhizal networks mediates complex adaptive behaviour in plant communities

Abstract

Trees can communicate with each other through networks in soil. Much like social networks or neural networks, the fungal mycelia of mycorrhizas allow signals to be sent between trees in a forest. These mycorrhizal networks are effectively an information highway, with recent studies demonstrating the exchange of nutritional resources, defence signals and allelochemicals. Sensing and responding to networked signals elicits complex behavioural responses in plants. This ability to communicate ('tree talk') is a foundational process in forest ecosystems.

Abstract

Adaptive behaviour of plants, including rapid changes in physiology, gene regulation and defence response, can be altered when linked to neighbouring plants by a mycorrhizal network (MN). Mechanisms underlying the behavioural changes include mycorrhizal fungal colonization by the MN or interplant communication via transfer of nutrients, defence signals or allelochemicals. We focus this review on our new findings in ectomycorrhizal ecosystems, and also review recent advances in arbuscular mycorrhizal systems. We have found that the behavioural changes in ectomycorrhizal plants depend on environmental cues, the identity of the plant neighbour and the characteristics of the MN. The hierarchical integration of this phenomenon with other biological networks at broader scales in forest ecosystems, and the consequences we have observed when it is interrupted, indicate that underground ‘tree talk’ is a foundational process in the complex adaptive nature of forest ecosystems.