Abstract Description

Arbuscular mycorrhizal (AM) fungi  form vast, continuous cytoplasmic networks that connect soil environments with plant roots and support one of the most prevalent symbioses on Earth. Their coenocytic structure allows resources, organelles, and signals to move across centimeter- to meter-scale mycelia without cellular boundaries, posing fundamental questions about coordination across scales. At the cellular level, AM fungal hyphae exhibit dynamic nuclear distributions and spatially organized lipid accumulation within a shared cytosol that supports sustained streaming and rapid physiological responses. At the network level, mycelial expansion follows coordinated waves of tip growth and filament thickening, coupling exploratory foraging with stabilization of transport capacity. These dynamics enable flexible allocation of carbon and nutrients while maintaining long-distance connectivity with host roots. Together, cell-scale organization and network-scale growth emerge as tightly linked processes that shape AM fungal function, efficiency, and resilience. We are only beginning to understand the AM fungal cell and its internal dynamics, and many open questions remain to be addressed in order to achieve a mechanistic understanding of how cellular organization and network behavior give rise to symbiotic function.