Presentation on theme: "Ascomycete Anamorphs and the Imperfect Fungi"— Presentation transcript:
1Ascomycete Anamorphs and the Imperfect Fungi Mycology (Bio 594, Special Topics)M. Marshall 2013Shippensburg University(See last slide for credits)
2Ascomycete anamorphsHave mitospore types that are produced on hyphal conidiophores, or on or in structures made from aggregated hyphae = conidiomata
3Most 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.
4Deuteromycetes “deuter-” Gk., meaning “second” @Deuteromycetes “deuter-” Gk., meaning “second”> 20,000 species of fungi in 2600 genera that have no known sexual stateMost belong in phylum AscomycotaThese fungi are also called:Anamorphic fungiMitosporic fungiConidial fungiImperfect fungiFungi imperfecti
5Asexual Propagules I – Other than Conidia Chlamydospore1-celled spore (usually thick-walled) designed for perennation; formed inside an existing hyphal cellSclerotium (pl. sclerotia)Rounded mass of hyphae, often differentiated into rind and medulla. Usually melanized
6Asexual propagules II Conidia Conidium (pl. conidia)Non-motile spore designed for dispersalWide range of shape, size, color and septation among taxa (details discussed in later slides).
7Saccardoan Spore Types & Imperfect Classification @Saccardoan Spore Types & Imperfect ClassificationP.A. Saccardo ( )“Sylloge Fungorum” ( )--names & descriptions of all known fungiDeveloped system of classifying fungi based on type of spore (shape, septation, color)
8Types of Deuteromycetes @Types of DeuteromycetesHyphomycetes—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 conidiomataCoelomycetes—fungi that produce conidia from conidiogenous cells formed in closed or semi-closed conidiomata such as an ascervulus or pycnidium
9Variations 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:
10Saccardoan Hyphomycete (form) Families @Moniliaceae—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
11An 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 pycnidiaMelanconiales – 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.
12Barnett’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 conidiaDematiaceae – darkly pigmented conidia (either singly or en mass).Both have conidiophores single and separate or in loose clusters.Sections:Amerosporae – conidia one-celled = amerosporesDidymosporae – conidia two-celled = didymosporesPhragmosporae – conidia with transverse septa only = phragmosporeDictyosporae – conidia with both transverse and oblique septation = dictyosporeScolecosporae – conidia filiform = scolecosporeStaurosporae – conidia stellate or branched = staurosporeHelicosporae – conidia coiled = helicosporeThe prefixes Hyalo- or Phaeo- are sometimes used with the above spore names to indicate hyaline or darkly pigmented respectively
13Barnett’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.
14Conidiophores Hyphae bearing conidiogenous cells @ConidiophoresHyphae bearing conidiogenous cellsMorphologically differentiated from vegetative hyphae (=macronematous)Morphologically not differentiated (=micronematous)
16Closed Conidiomata (Coelomycetes) Acervulus PycnidiumConidium 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.
18Open conidiomata: Synnemata @Open conidiomata: SynnemataConidiophores 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.
19Open Conidiomata: Sporodochium @Open Conidiomata: 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)
23Arrangement of conidia at locus @Arrangement of conidia at locusSolitary Catenate = true chainsSeriate = false chains, spore headsDry sporesWet spores (gleoid)
24@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)
25@SynanamorphTwo or more types of asexual spores formed by the same fungusExample:Ceratocystis fibriata
26Conidiogenous Cells A cell that forms one or more conidia @Conidiogenous CellsA cell that forms one or more conidiaMay be formed on a specialized, simple, or branched hypha called a conidiophore
28Conidial Development (Ontogeny) @Conidial Development (Ontogeny)Blastic—blowing out of conidial initial prior to formation of delimiting septumThallic—conversion of segment of existing hyphae into conidia
29Blastic versus thallic @Blastic versus thallicCole, 1986
30Blastic 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.
31Blastic Anamorph and Hyphomycete (imperfect) examples
32Blastic 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 .
33Blastic development Holoblastic Enteroblastic @Blastic developmentHoloblasticsingle 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
36Enteroblastic development detail Phialidic—a basipetal succession of conidia is formed from a fixed locus on the conidiogenous cell (phialide)collarette
37Enteroblastic 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)
38More Enteroblastic development @More Enteroblastic developmentTretic—the inner wall of the conidiogenous cell blows out through a hole (pore) in the outer wall like a balloon to form a conidium.
39Thallic 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.
40Arrangement of conidia at locus @Arrangement of conidia at locusSolitary Catenate = true chainsSeriate = false chains, spore headsDry sporesWet spores (gleoid)
41@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)
42CreditsThis 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.