Abstract
Filamentous fungi feature a network termed mycelium, comprising chains of elongated cells (hyphae) that repeatedly branch and fuse. In forest ecosystems, filamentous fungi play important roles in the decomposition of plant materials such as dead trees and fallen leaves, and mycorrhizal fungi engage in mutualistic relationships with plant roots. Understanding the development and dynamics of mycelial networks is important when studying material cycling and the inter- and intra-species interactions that sustain forest ecosystems. In this review, we summarize current knowledge on the behavioral characteristics of hyphae and mycelial networks, and the transport of substances and signals from a single hypha to the entire mycelial network. We highlight existing challenges. The tip of an extending hypha features polarity, and thus a memory of the direction of growth, enabling seemingly complex tasks such as maze navigation. It seems that feature-memory and decision-making capacities extend to entire mycelial networks, but the details remain poorly understood. If a fungus is to change its shape and behavior, it must auto-digest unnecessary components and transfer building blocks to newly important regions, but it is unclear how such processes are regulated throughout a mycelial network. Research on mycelial behavior poses many challenges, but progress in network analysis, microfluidic devices, and bioimaging platforms will greatly aid future research.
