3 From: Fischer-Parton et al. 2000. J. Microscopy 198 (3): 246-259 Exocytosis—enzymes (pectinases, cellulases, proteases) to degrade compounds in the environmentEndocytosis—removal of excess plasma membrane, recycling membrane proteins, transport of membrane proteins & lipids to vacuole for degradation, uptake of molecules, etc.
4 ?MannoproteinsGlucan synthaseWall-lytic enzymes, protease activatorsChitosomes (chitin synthase)Multivesicular bodiesWall substratesEnzyme activators (GTP), inhibitorDelivered from cytosol?Components probably delivered by membrane-bound vesiclesplasmalemmawallComponents of wall synthesis at hyphal tip Modified from Deacon (2006). Fungal Biology.
5 Asexual SporulationSporangiospores formed by cleavage of protoplasm in a multinucleate sporangium (Chytridiomycota, Zygomycota, Oomycota)Conidia develop directly from hyphae or from modified hyphal cells called conidiogenous cells (Ascomycota including Deuteromycetes, some Basidiomycota)
6 Control of asexual sporulation May be triggered by changes in carbon:nitrogen ratio in growth mediumMay require light trigger, e.g. near-ultraviolet lightUnder control of sporulation genes:One group involved in switch from somatic growth to sporulationA second group regulates developmental stages of sporulationA third group regulates secondary aspects including spore color
8 Deuteromycetes “deuter-” Gk., meaning “second” > 20,000 species of fungi in 2600 genera have no known sexual stateMost belong in phylum AscomycotaThese fungi are also called:Anamorphic fungiMitosporic fungiConidial fungiImperfect fungiFungi imperfecti
9 Asexual propagules Chlamydospore Sclerotium (pl. sclerotia) 1-celled spore (usually thick-walled) designed for perennation; formed inside existing cellSclerotium (pl. sclerotia)Rounded mass of hyphae, often differentiated into rind and medulla
10 Asexual propagules Conidium (pl. conidia) Non-motile spore designed for dispersalWide range of shape, size, color and septation among taxa
21 Blastic development Holoblastic Enteroblastic single conidium is formed from conidiogenous locus, all wall layers involved in formation of conidium wallEnteroblasticmore than one conidium formed from locus, only the inner wall layer(s) involved in formation of conidium wall
23 Holoblastic/synchronous Holoblastic/sympodialFrom Hawksworth et al., 1995
24 Enteroblastic development Phialidic—a basipetal succession of conidia is formed from a fixed locus on the conidiogenous cell (phialide)collarette
25 Enteroblastic development Annellidic—a basipetal succession of conidia formed by repeated percurrent proliferation of conidiogenous locus, leaving the distal end of locus with transverse scars (annellations)
26 Enteroblastic development Tretic—the inner wall of the conidiogenous cell blows out through a hole (pore) in the outer wall like a balloon to form a conidium.
27 Arrangement of conidia at locus Solitary Catenate = true chainsSeriate = false chains, spore headsDry sporesWet spores (gleoid)
28 Succession of conidiaBasipetal = a chain of conidia in which new spores are formed at the base, the oldest conidia are at the apexAcropetal = a chain of conidia with the new spores formed at the end of the chain, oldest spores are at the base. In order for this type of conidial formation to occur, the conidia must function as conidiogenous cells (e.g., Alternaria, Cladosporium)
34 Types of Deuteromycetes Hyphomycetes—fungi that produce conidia from conidiogenous cells free on their myceliaMay be formed on the surface of synnemata or sporodochiaCoelomycetes—fungi that produce conidia from conidiogenous cells formed in conidiomata
35 SynnemataConidiophores united at baseConidiogenous cells at apex
36 SporodochiumA compact, cushion-like aggregation of hyphae on which conidiophores are formed in a dense layerThe aggregation of hyphae is called a stroma (pl. stromata)
37 HyphomycetesMoniliaceae—conidiophores formed singly, hyphae and conidia pale-coloredDematiaceae—conidiophores formed singly, hyphae and/or conidia dark-coloredTuberculariaceae—conidiophores aggregated on cushion-like sporodochium (pl. sporodochia)Stilbaceae—conidiophores aggregated in a synnema (pl. synnemata), an erect bundle with conidia formed at apex