Fungal Growth and Fungal Growth and Sporulation Sporulation
Dec 15, 2015
From: Fischer-Parton et al. 2000. J. Microscopy 198 (3): 246-259
Exocytosis—enzymes (pectinases, cellulases, proteases) to degrade compounds in the environment
Endocytosis—removal of excess plasma membrane, recycling membrane proteins, transport of membrane proteins & lipids to vacuole for degradation, uptake of molecules, etc.
?
Mannoproteins
Glucan synthase
Wall-lytic enzymes, protease activators
Chitosomes (chitin synthase)
Multivesicular bodies
Wall substrates
Enzyme activators (GTP), inhibitor
Delivered from cytosol?
Components probably delivered by membrane-bound vesicles
Delivered from cytosol?
plasmalemma
wall
Components of wall synthesis at hyphal tip. Modified from Deacon (2006). Fungal Biology.
Asexual SporulationAsexual Sporulation
Sporangiospores formed by cleavage of Sporangiospores formed by cleavage of protoplasm in a multinucleate sporangium protoplasm in a multinucleate sporangium (Chytridiomycota, Zygomycota, Oomycota)(Chytridiomycota, Zygomycota, Oomycota)
Conidia develop directly from hyphae or Conidia develop directly from hyphae or from modified hyphal cells called from modified hyphal cells called conidiogenous cells (Ascomycota conidiogenous cells (Ascomycota including Deuteromycetes, some including Deuteromycetes, some Basidiomycota)Basidiomycota)
Control of asexual sporulationControl of asexual sporulation
May be triggered by changes in carbon:nitrogen May be triggered by changes in carbon:nitrogen ratio in growth mediumratio in growth medium
May require light trigger, e.g. near-ultraviolet May require light trigger, e.g. near-ultraviolet lightlight
Under control of sporulation genes:Under control of sporulation genes: One group involved in switch from somatic growth to One group involved in switch from somatic growth to
sporulationsporulation A second group regulates developmental stages of A second group regulates developmental stages of
sporulationsporulation A third group regulates secondary aspects including A third group regulates secondary aspects including
spore colorspore color
DeuteromycetesDeuteromycetes““deuterdeuter-” Gk., meaning “second”-” Gk., meaning “second”
> 20,000 species of fungi in 2600 genera > 20,000 species of fungi in 2600 genera have no known sexual state have no known sexual state
Most belong in phylum AscomycotaMost belong in phylum AscomycotaThese fungi are also called:These fungi are also called:
Anamorphic fungiAnamorphic fungiMitosporic fungiMitosporic fungiConidial fungiConidial fungi Imperfect fungiImperfect fungiFungi imperfectiFungi imperfecti
Asexual propagulesAsexual propagules
ChlamydosporeChlamydospore 1-celled spore (usually 1-celled spore (usually
thick-walled) designed for thick-walled) designed for perennation; formed perennation; formed inside existing cellinside existing cell
Sclerotium (pl. sclerotia)Sclerotium (pl. sclerotia) Rounded mass of hyphae, Rounded mass of hyphae,
often differentiated into often differentiated into rind and medullarind and medulla
Asexual propagulesAsexual propagules
Conidium (pl. conidia)Conidium (pl. conidia) Non-motile spore Non-motile spore
designed for dispersaldesigned for dispersal Wide range of shape, Wide range of shape,
size, color and size, color and septation among taxaseptation among taxa
Saccardoan Spore TypesSaccardoan Spore Types
P.A. Saccardo (1845-P.A. Saccardo (1845-1920)1920) ““Sylloge Fungorum” Sylloge Fungorum”
(1882-1972)--names & (1882-1972)--names & descriptions of all descriptions of all known fungiknown fungi
Developed system of Developed system of classifying fungi based classifying fungi based on type of spore on type of spore (shape, septation, (shape, septation, color)color)
Saccardoan Spore TypesSaccardoan Spore Types
ColorColor Hyaline or bright (hyalo-)Hyaline or bright (hyalo-) Pigmented (phaeo-)Pigmented (phaeo-)
Shape and septationShape and septation 1-celled—amerospore1-celled—amerospore 2-celled—didymospore2-celled—didymospore Multicelled—phragmosporeMulticelled—phragmospore Muriform—dictyosporeMuriform—dictyospore Filiform—scolecosporeFiliform—scolecospore Helical—helicosporeHelical—helicospore Branched--staurospore Branched--staurospore
Saccardoan Spore TypesSaccardoan Spore Types
amerosporestaurospore
helicospore
scolecospore
dictyospore
didymospore
phragmospore
SynanamorphSynanamorph
Two or more types of Two or more types of asexual spores asexual spores formed by the same formed by the same fungusfungus
Example:Example: Ceratocystis fibriataCeratocystis fibriata
Conidiogenous CellsConidiogenous Cells
A cell that forms one A cell that forms one or more conidiaor more conidia
May be formed on a May be formed on a specialized simple or specialized simple or branched hypha branched hypha called a conidiophorecalled a conidiophore
Conidial Development (Ontogeny)Conidial Development (Ontogeny)
Blastic—blowing out of conidial initial prior Blastic—blowing out of conidial initial prior to formation of delimiting septumto formation of delimiting septum
Thallic—conversion of segment of existing Thallic—conversion of segment of existing hyphae into conidiahyphae into conidia
Blastic developmentBlastic development
HoloblasticHoloblasticsingle conidium is formed from conidiogenous single conidium is formed from conidiogenous
locus, all wall layers involved in formation of locus, all wall layers involved in formation of conidium wallconidium wall
EnteroblasticEnteroblasticmore than one conidium formed from locus, more than one conidium formed from locus,
only the inner wall layer(s) involved in only the inner wall layer(s) involved in formation of conidium wallformation of conidium wall
Enteroblastic developmentEnteroblastic development
PhialidicPhialidic—a basipetal —a basipetal succession of conidia succession of conidia is formed from a fixed is formed from a fixed locus on the locus on the conidiogenous cell conidiogenous cell (phialide)(phialide)
collarette
Enteroblastic developmentEnteroblastic development
AnnellidicAnnellidic—a —a basipetal succession basipetal succession of conidia formed by of conidia formed by repeated percurrent repeated percurrent proliferation of proliferation of conidiogenous locus, conidiogenous locus, leaving the distal end leaving the distal end of locus with of locus with transverse scars transverse scars (annellations)(annellations)
Enteroblastic developmentEnteroblastic development
TreticTretic—the inner wall —the inner wall of the conidiogenous of the conidiogenous cell blows out through cell blows out through a hole (pore) in the a hole (pore) in the outer wall like a outer wall like a balloon to form a balloon to form a conidium.conidium.
Arrangement of conidia at locusArrangement of conidia at locus
Solitary Solitary Catenate = true chainsCatenate = true chainsSeriate = false chains, spore headsSeriate = false chains, spore heads
Dry sporesDry sporesWet spores (gleoid)Wet spores (gleoid)
Succession of conidiaSuccession of conidia
Basipetal Basipetal = a chain of conidia in which new = a chain of conidia in which new spores are formed at the base, the oldest spores are formed at the base, the oldest conidia are at the apexconidia are at the apex
AcropetalAcropetal = a chain of conidia with the new = a chain of conidia with the new spores formed at the end of the chain, oldest spores formed at the end of the chain, oldest spores are at the base. In order for this type of spores are at the base. In order for this type of conidial formation to occur, the conidia must conidial formation to occur, the conidia must function as conidiogenous cells (e.g., function as conidiogenous cells (e.g., AlternariaAlternaria, , CladosporiumCladosporium))
ConidiophoresConidiophores
Hyphae bearing conidiogenous cellsHyphae bearing conidiogenous cellsMorphologically differentiated from vegetative Morphologically differentiated from vegetative
hyphae (=macronematous)hyphae (=macronematous)Morphologically not differentiated Morphologically not differentiated
(=micronematous)(=micronematous)
Types of DeuteromycetesTypes of Deuteromycetes
HyphomycetesHyphomycetes—fungi that produce —fungi that produce conidia from conidiogenous cells free on conidia from conidiogenous cells free on their myceliatheir myceliaMay be formed on the surface of May be formed on the surface of synnematasynnemata
or or sporodochiasporodochiaCoelomycetesCoelomycetes—fungi that produce conidia —fungi that produce conidia
from conidiogenous cells formed in from conidiogenous cells formed in conidiomataconidiomata
SynnemataSynnemata
Conidiophores united Conidiophores united at baseat base
Conidiogenous cells Conidiogenous cells at apexat apex
SporodochiumSporodochium
A compact, cushion-A compact, cushion-like aggregation of like aggregation of hyphae on which hyphae on which conidiophores are conidiophores are formed in a dense formed in a dense layerlayer
The aggregation of The aggregation of hyphae is called a hyphae is called a stroma (pl. stromata)stroma (pl. stromata)
HyphomycetesHyphomycetes
MoniliaceaeMoniliaceae—conidiophores formed singly, —conidiophores formed singly, hyphae and conidia pale-coloredhyphae and conidia pale-colored
DematiaceaeDematiaceae—conidiophores formed singly, —conidiophores formed singly, hyphae and/or conidia dark-coloredhyphae and/or conidia dark-colored
TuberculariaceaeTuberculariaceae—conidiophores aggregated —conidiophores aggregated on cushion-like sporodochium (pl. sporodochia)on cushion-like sporodochium (pl. sporodochia)
StilbaceaeStilbaceae—conidiophores aggregated in a —conidiophores aggregated in a synnema (pl. synnemata), an erect bundle with synnema (pl. synnemata), an erect bundle with conidia formed at apexconidia formed at apex