Ascomycete Anamorphs and the Imperfect Fungi

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1 Ascomycete Anamorphs and the Imperfect Fungi
Mycology (Bio 594, Special Topics) M. Marshall 2013 Shippensburg University (See last slide for credits)

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

3 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.

4 Deuteromycetes “deuter-” Gk., meaning “second”
@ Deuteromycetes “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

5 Asexual Propagules I – Other than Conidia
Chlamydospore 1-celled spore (usually thick-walled) designed for perennation; formed inside an existing hyphal cell Sclerotium (pl. sclerotia) Rounded mass of hyphae, often differentiated into rind and medulla. Usually melanized

6 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).

7 Saccardoan Spore Types & Imperfect Classification
@ Saccardoan Spore Types & Imperfect Classification P.A. Saccardo ( ) “Sylloge Fungorum” ( )--names & descriptions of all known fungi Developed system of classifying fungi based on type of spore (shape, septation, color)

8 Types of Deuteromycetes
@ Types of Deuteromycetes Hyphomycetes—fungi that produce conidia from conidiogenous cells free on their mycelia ( on conidiophores). May be formed on the surface of synnematal or sporodochial types of conidiomata Coelomycetes—fungi that produce conidia from conidiogenous cells formed in closed or semi-closed conidiomata such as an ascervulus or pycnidium

9 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:

10 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

11 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.

12 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 = phragmospore 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

13 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.

14 Conidiophores Hyphae bearing conidiogenous cells
@ Conidiophores Hyphae bearing conidiogenous cells Morphologically differentiated from vegetative hyphae (=macronematous) Morphologically not differentiated (=micronematous)

15 Conidiophores

16 Closed Conidiomata (Coelomycetes)
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.

17 Pycnidium details

18 Open conidiomata: Synnemata
@ Open conidiomata: Synnemata 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.

19 Open Conidiomata: Sporodochium
@ 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)

20 Saccardoan Spore Types
staurospore helicospore scolecospore dictyospore didymospore phragmospore amerospore

21 More Saccardoan Spore Type Terminology
@ More Saccardoan Spore Type Terminology Color (prefixes) Hyaline or bright (hyalo-) Pigmented (phaeo-) Shape and septation 1-celled —amerospore 2-celled —didymospore Multicelled —phragmospore Muriform —dictyospore (with both vert. & horiz. cross walls) Filiform —scolecospore (hair-like) Helical — helicospore Branched — staurospore (see also slide 11)

22 @

23 Arrangement of conidia at locus
@ Arrangement of conidia at locus Solitary  Catenate = true chains Seriate = false chains, spore heads Dry spores Wet spores (gleoid)

24 @ Succession of conidia 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)

25 @ Synanamorph Two or more types of asexual spores formed by the same fungus Example: Ceratocystis fibriata

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

27 @ From D. Malloch

28 Conidial Development (Ontogeny)
@ Conidial Development (Ontogeny) Blastic—blowing out of conidial initial prior to formation of delimiting septum Thallic—conversion of segment of existing hyphae into conidia

29 Blastic versus thallic
@ Blastic versus thallic Cole, 1986

30 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.

31 Blastic Anamorph and Hyphomycete (imperfect) examples

32 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 .

33 Blastic development Holoblastic Enteroblastic
@ Blastic development 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

34 Holoblastic

35 Enteroblastic

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

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

38 More Enteroblastic development
@ More 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.

39 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.

40 Arrangement of conidia at locus
@ Arrangement of conidia at locus Solitary  Catenate = true chains Seriate = false chains, spore heads Dry spores Wet spores (gleoid)

41 @ Succession of conidia 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)

42 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.

43 Fungal symbiosies