Mycology (Bio 594, Special Topics)
M. Marshall 2013
Shippensburg University
(See last slide for credits)

Ascomycete anamorphs
Have mitospore types that are produced on hyphal conidiophores, or on or in structures made from aggregated hyphae = conidiomata

Most micro-fungi are first encountered as the imperfect stage
Although many fungi may in fact be the imperfect asexual
( anamorphic ) form of a fungus with an perfect
( teleomorph ) stage, usually the production of the latter stage requires two opposite mating types to unite on specific substrates and/or under limited conditions. Years may elapse between the discovery of an asexual isolate and its sexual form. So many fungi that are important in human affairs are known only by their asexual designation.
Some later prove to have a sexual stage and some not.

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“ deuter” Gk., meaning “ second ”
• > 20,000 species of fungi in 2600 genera that have no known sexual state
• Most belong in phylum Ascomycota
• These fungi are also called:
 Anamorphic fungi
 Mitosporic fungi
 Conidial fungi
 Imperfect fungi
 Fungi imperfecti

• Chlamydospore
– 1-celled spore (usually thickwalled) designed for perennation; formed inside an existing hyphal cell
• Sclerotium (pl. sclerotia)
– Rounded mass of hyphae, often differentiated into rind and medulla. Usually melanized

Asexual propagules II Conidia
Conidium (pl. conidia)
– Non-motile spore designed for dispersal
– Wide range of shape, size, color and septation among taxa (details discussed in later slides).

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• P.A. Saccardo (1845-
1920)
– “ Sylloge Fungorum ”
( 1882 -1972)--names & descriptions of all known fungi
– Developed system of classifying fungi based on type of spore (shape, septation, color)

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• Hyphomycetes — fungi that produce conidia from conidiogenous cells free on their mycelia ( on conidiophores).
– May be formed on the surface of synnemata l or sporodochia l types of conidiomata
• Coelomycetes — fungi that produce conidia from conidiogenous cells formed in closed or semi-closed
conidiomata such as an ascervulus or pycnidium

Variations of Deuteromycete grouping
As with all things mycological, the Saccardoan system has been modified over the years (there are different versions) and other systems have been proposed as well:

@ Saccardoan Hyphomycete (form) Families
• Moniliaceae—conidiophores formed singly , hyphae and conidia pale-colored
• Dematiaceae—conidiophores formed singly , hyphae and/or conidia dark-colored
• Tuberculariaceae—conidiophores aggregated on cushion-like sporodochium (pl. sporodochia)
• Stilbaceae—conidiophores aggregated in a synnema
(pl. synnemata), an erect bundle with conidia formed at apex

An alternative, Saccardoan Form Orders according to
Barnett*
Moniliales – Conidia directly on mycelium, on conidiogenous cells or conidiophores which may be separate, in clusters, or tightly packed groups. The largest and most commonly represented group.
Sphaeropsidales – Conidia produced in well defined pycnidia
Melanconiales – Conidia naturally produced in acervuli ; in culture possibly singly or in compact groups resembling sporodochia of the Moniliales.
Mycelia Sterilia – No conidia production. Form sclerotia or other survival structures.
Some authors include the conidial Oomycetes (old: Phycomycetes) here also because of their superficial similarity to the true fungi imperfects.

Barnett’s Saccardoan Families and Sections of the Moniliales I
Moniliales – Conidia directly on mycelium, on conidiogenous cells or conidiophores which may be separate, in clusters, or tightly packed groups. The largest and most commonly represented group.
Moniliaceae – hyaline conidia
Dematiaceae – darkly pigmented conidia (either singly or en mass).
Both have conidiophores single and separate or in loose clusters.
Sections:
Amerosporae – conidia one-celled = amerospores
Didymosporae – conidia two-celled = didymospores
Phragmosporae – conidia with transverse septa only = phragmospor e
Dictyosporae – conidia with both transverse and oblique septation
= dictyospore
Scolecosporae – conidia filiform = scolecospore
Staurosporae – conidia stellate or branched = staurospore
Helicosporae – conidia coiled = helicospore
The prefixes Hyalo- or Phaeo- are sometimes used with the above spore names to indicate hyaline or darkly pigmented respectively

Barnett’s* Saccardoan Families and Sections of the Moniliales II
Tubiculariaceae – Conidiophores compacted into a rounded or flat sporodochium which may not be produced in culture.
Stilbaceae – Conidiophores compacted into synnemata , but may also produce single conidiophores of the Moniliaceous or demateaceous type (previous slide).
* H.L. Barnett was an accomplished mycologist who worked at west Virginia University. At various times he was President of the American Phytopathological
Society and the Mycological Society of America. His book, Illustrated genera of Imperfect Fungi has gone through 4 editions and is still a major “Imperfect” reference today.

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Hyphae bearing conidiogenous cells
– Morphologically differentiated from vegetative hyphae (= macronematous )
– Morphologically not differentiated
(= micronematous )

Acervulus Pycnidium
Conidium containing structures that rupture through host epithelium.
An acervulus is more open, not within walls of fungal tissue. The pycnidium is perithecium like, but contains short conidiophores and mitosporic conidia, not asci. In some ascomycete fungi the pycnidial walls develop into stroma within which true perithecia develop.

Pycnidium details

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Open conidiomata: Synnemat a
• Conidiophores united at base grow in parallel to give a “tree trunk” like configuration.
• Conidiogenous cells at apex.
• Conidia may be produced dry or formed in a liquid matrix.

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Open Conidiomata: Sporodochium
• A compact, cushion-like aggregation of hyphae on which conidiophores are formed in a dense layer
• The aggregation of hyphae is called a stroma (pl. stromata)

scolecospore amerospore staurospore helicospore dictyospore phragmospore didymospore

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• Color (prefixes)
– Hyaline or bright ( hyalo-)
– Pigmented ( phaeo -)
• Shape and septation
– 1-celled — amerospore
– 2-celled — didymospor e
– Multicelled — phragmospore
– Muriform — dictyospore (with both vert. & horiz. cross walls)
– Filiform — scolecospore (hair-like)
– Helical — helicospore
– Branched — staurospore
(see also slide 11)

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• Solitary
• Catenate = true chains
• Seriate = false chains, spore heads
– Dry spores
– Wet spores (gleoid)

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• Basipetal = a chain of conidia in which new spores are formed at the base , the oldest conidia are at the apex
• Acropetal = 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)

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• Two or more types of asexual spores formed by the same fungus
• Example:
– Ceratocystis fibriata

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• A cell that forms one or more conidia
• May be formed on a specialized, simple, or branched hypha called a conidiophore

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From D. Malloch

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• Blastic —blowing out of conidial initial prior to formation of delimiting septum
• Thallic —conversion of segment of existing hyphae into conidia

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Cole, 1986

Blastic vs thallic conidiogenesis & spore separation
Blastic = cross wall follows “budding”, thallic = cross wall defines the spore as separate.
Schizolytic separation = septae split ; rheolytic = wall of basal cell splits.

Blastic Anamorph and Hyphomycete (imperfect) examples

Blastic types: precurrent, phialidic, and retrogrssive
Precurrent = leaves ring-like scar on conidiogenous cell (Venturia).
Phialidic = Conidia pushed out of end of conidiogenous phialid
(Penicillium, Aspergilous).
Retrogressive = sepatate form down the conidiophore underneath the first (?)
Basauxic retrogressive-like alternative = chain of blaststic conidia where new growth is added from a mother cell below .

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• Holoblastic
– single conidium is formed from conidiogenous locus, all wall layers involved in formation of conidium wall
• Enteroblastic
– more than one conidium formed from locus, only the inner wall layer(s) involved in formation of conidium wall

• Phialidic —a basipetal succession of conidia is formed from a fixed locus on the conidiogenous cell
(phialide) collarette

• Annellidic —a basipetal succession of conidia formed by repeated percurrent proliferation of conidiogenous locus, leaving the distal end of locus with transverse scars (annellations)

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• 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.

Thallic arthric, alt. arthric, and solitary
Arthric = growth stops hyphae divided up by arrising septae. Fracture at sepatae.
Alternate-arthric = some intervening cells in the arthric chain degenerate to release the others as conidia.
Solitary = single large spores develop, may be multicellular.

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• Solitary
• Catenate = true chains
• Seriate = false chains, spore heads
– Dry spores
– Wet spores (gleoid)

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• Basipetal = a chain of conidia in which new spores are formed at the base, the oldest conidia are at the apex
• Acropetal = 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)

Credits
This presentation has been modified from one posted on the web by Dr. Lori Carris, Washigton State University
Plant Pathology Dept. from her course: Plant Path 521,
Mycology.

Fungal symbiosies