Fungal Morphogenesis, from the Polarized Growth of Hyphae to Complex Reproduction and Infection Structures

Abstract

SUMMARYFilamentous fungi constitute a large group of eukaryotic microorganisms that grow by forming simple tube-like hyphae that are capable of differentiating into more-complex morphological structures and distinct cell types. Hyphae form filamentous networks by extending at their tips while branching in subapical regions. Rapid tip elongation requires massive membrane insertion and extension of the rigid chitin-containing cell wall. This process is sustained by a continuous flow of secretory vesicles that depends on the coordinated action of the microtubule and actin cytoskeletons and the corresponding motors and associated proteins. Vesicles transport cell wall-synthesizing enzymes and accumulate in a special structure, the Spitzenkörper, before traveling further and fusing with the tip membrane. The place of vesicle fusion and growth direction are enabled and defined by the position of the Spitzenkörper, the so-called cell end markers, and other proteins involved in the exocytic process. Also important for tip extension is membrane recycling by endocytosis via early endosomes, which function as multipurpose transport vehicles for mRNA, septins, ribosomes, and peroxisomes. Cell integrity, hyphal branching, and morphogenesis are all processes that are largely dependent on vesicle and cytoskeleton dynamics. When hyphae differentiate structures for asexual or sexual reproduction or to mediate interspecies interactions, the hyphal basic cellular machinery may be reprogrammed through the synthesis of new proteins and/or the modification of protein activity. Although some transcriptional networks involved in such reprogramming of hyphae are well studied in several model filamentous fungi, clear connections between these networks and known determinants of hyphal morphogenesis are yet to be established.

Myosin XI Interacting with a RabE GTPase Is Required for Polarized Growth

“…In addition, the diffuse cytoplasmic signal and the distinct localization to the growing apical zone are consistent with secretory vesicle localization (Furt et al, 2013;Bibeau et al, 2018). This type of localization is reminiscent of commonly observed localization patterns of F-actin, secretory vesicles, myosin XI/V, and other secretory components across plants and fungi (Bi and Park, 2012;Hepler and Winship, 2015;Riquelme et al, 2018).…”

Comparative genomics reveals the origin of fungal hyphae and multicellularity

“…While the origins of hyphae are poorly known, information on the molecular and cellular basis of hyphal morphogenesis is abundant (for recent reviews see refs 33–38 ), permitting evolutionary genomic analyses of the origins of hyphae. Hyphal morphogenesis builds on cell polarization networks 39 , the exo-and endocytotic machinery 40 , long range vesicle transport as well as fungal-specific traits such as cell wall synthesis and assembly 41 , and the selection of branching points and sites of septation 42 , among others.…”

Phosphatidic acid produced by phospholipase D is required for hyphal cell-cell fusion and fungal-plant symbiosis

“…Fimbrin localised to actin patches at the endocytic collar, where it is known to crosslink with actin filaments. These filaments coat endocytic vesicles and provide mechanical force for membrane invagination (Riquelme et al, 2018, Aghamohammadzadeh & Ayscough, 2009). In the DpldB deletion strains, the Fimbrin-GFP fusion protein, while also detected at the endocytic collar, was found to collect at the hyphal tip more often than in WT hyphae.…”