XVI International Botanical Congess

Fungal hyphae grow by tip growth and mycelium formation entails the initiation of branches in mature hyphae. Growing tips require localized concentrations of molecules related to ion fluxes, vesicle transport and fusion, cell wall synthesis and determination of tip morphology, and branch initiation demands the de novo assembly of these. Components of the cytoskeleton are responsible for many, possibly all, of these distributions and activities, including assembly at branch sites. F-actin is the main player, probably augmented by a spectrin-related protein. Microtubules are not essential for maintenance of tubular growth or initiation of new tips during branching, spore germination or protoplast regeneration. An autocatalytic system involving localization of Ca2+ channels by F-actin and Ca2+ fluxes modulating F-actin arrays is an attractive possibility for regulation of tip growth.