Form follows function -- the versatile fungal cytoskeleton

The cytoskeleton plays a major role in the regulation of fungal cell morphogenesis. The fungal cytoskeleton is comprised of three polymers: F-actin, microtubules and septins. Due to the successful application of the newly developed Lifeact probe for live-cell imaging of F-actin it is now possible, in combination with existing microtubule markers and fluorescently labelled septins, to monitor real-time dynamics of the entire fungal cytoskeleton, and reassess the many and integrated roles of F-actin, microtubules and septins throughout fungal growth and development. Evidence is accumulating that functional properties of higher-order structures derived from actin and septin filaments interacting with microtubules are employed in different ways in different cell types. This may reflect marked differences in cytoskeletal architecture that are found, for example, in unicellular yeasts, spore germlings and mature fungal hyphae. In this review we address key aspects of the versatile fungal cytoskeleton, highlight recently gained insights into important roles of F-actin in filamentous fungi, and raise some key questions that are likely to be solved in the coming years based on the new experimental tools that have recently become available.