Hyphae are tubular structures that constitute the basic unit of a fungal mycelium. It is the efficient growth of hyphae that plays a crucial role in fungal colonisation of a substrate. Hyphal growth is driven by localised cell surface expansion and cell wall deposition at the hyphal tip. Spatial and temporal regulatory mechanisms enforce this growth pattern by controlling the recruitment of the morphogenetic machinery, which consists of the cytoskeletal and vesicle trafficking elements that mobilise the precursors needed for growth. In addition to the establishment and maintenance of hyphal polarity, the ability to regulate the termination of polarised growth is likely to be important because it facilitates transitions from hyphal growth to development or pathogenesis. Hyphal growth presumably evolved as an adaptation that enabled filamentous fungi to efficiently colonise terrestrial habitats.
Key Concepts:
Hyphal growth is the defining feature of filamentous fungi.
The morphogenetic machinery consists of those elements of the cytoskeleton and vesicle trafficking components that are needed to drive extension of the hyphal tip.
The Spitzenkörper is a vesicle supply and transit centre located at the hyphal tip that is required for optimal rates of tip extension.
The spatial separation of exocytosis and endocytosis within the hyphal tip complex enables rapid tip extension.
The direction of hyphal extension is regulated by a microtubule‐based marking system that conveys positional information to the morphogenetic machinery.
Reactive oxygen species and calcium appear to serve as signals that regulate tip growth and the emergence of branches.
Duplication cycle describes the events that encompass the doubling of cell mass and nuclear numbers during hyphal growth.
The termination of polarised hyphal growth is often a key prerequisite for development and pathogenesis.
The hyphal mode of growth appears to have independently evolved on multiple occasions during evolution.