Detromycetes , Deutromycota Hendra UNESA
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Transcript of Detromycetes , Deutromycota Hendra UNESA
8/2/2019 Detromycetes , Deutromycota Hendra UNESA
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DeuteromycotaDeuteromycota Phylum: DeuteromycotaPhylum: DeuteromycotaCommonly referred to as the Fungi Imperfecti or imperfect fungi.
Classification based on asexual stagebecause:
Sexual reproduction rare, occurs onlyin narrow environmental parameters.Sexual phase of life cycle no longerexist.
Phylum: DeuteromycotaPhylum: Deuteromycota
Only asexual reproduction occurs,typically conidiaconidia borne onconidiophoresconidiophores.Classified according to conidia color,shape, size and number of septa.FormForm taxontaxon:: An artificial classificationscheme.When sexual reproduction discovered,usually an Ascomycota or less often
Basidiomycota.
Phylum: DeuteromycotaPhylum: Deuteromycota
When mycelial septate.
Thallus also may be yeast or dimorphic.
When sexual reproduction discovered,usually an Ascomycota or less oftenBasidiomycota.
Purpose of DeuteromycotaPurpose of Deuteromycota
Division was erected to accommodateconidia producing fungi with unknownsexual cycle.
When sexual stage discovered,species would be reclassifiedaccording to sexual stage.
In practice this concept did not work.
Purpose of DeuteromycotaPurpose of Deuteromycota
Instead, recall example of Emericella variecolor (=Aspergillus variecolor ).
Emericella variecolor , the sexual
stage is the telomorphtelomorph.Aspergillus variecolor , the asexualstage is the anamorphanamorph.
Thus, sexual stage is often present.
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DefiningDefining TaxaTaxa in Deuteromycotain Deuteromycota
Taxonomy of Deuteromycota basedmostly on spore morphology
SaccardoanSaccardoan System of sporeSystem of sporeclassificationclassification.
Oldest system of defining taxa infungi.
Artificial means of classification.No longer used in other taxa.
SaccardoanSaccardoan System ofSystem ofSpore Classification.Spore Classification.
Amerosporae: Conidia one celled,sphaerical, ovoid to elongate or
short cylindric.Allantosporae:Conidia bean-shaped, hyalineto dark.Hyalosporae:Conidia hyalinePhaeosporae:
Conidia dark.
Didymosporae: Conidia Ovoidto oblong, one septate
Hyalodidymospore:Conidia Hyaline.
Phaeodidymospore:Conidia dark.
Phragmosporae: Conidia oblong,two to many transverse septa
HyalophramosporeHyalophramospore:Conidia hyaline.
PhaeophramosporePhaeophramospore:Conidia dark.
Dictyosporae: Conidia ovoid tooblong, transversely andlongitudinally septate.
Hyalodictyospore:Conidia hyaline.
Phaeodictyospore:Conidia dark.
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Scolecosporae: Conidia threadliketo wormlike, septate or not,
hyaline or dark
Staurosporae: Conidia stellate,septate or not, hyaline or dark
Helicosporae: Conidia helical,septate or not, hyaline or dark
Classification of DeuteromycotaClassification of Deuteromycota
We will recognize a single class:DeuteromycetesDeuteromycetes, with four orders:
MonilialesMoniliales
SphaeropsidalesSphaeropsidales
MelanconialesMelanconiales
MyceliaMycelia SterilisSterilis
MonilialesMoniliales
Conidia and conidiophores borne onmycelium.
Yeast or dimorphic.
Not produce in pynidium or acervulus.
MonilialesMonilialesOrder: Moniliales (Alternaria tenuis )
conidiophore
conidium
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MonilialesMonilialesOrder: Moniliales (Alternaria tenuis )
MonilialesMonilialesOrder: Moniliales (Sporobolomyces )
Example of an asexual yeast.
MonilialesMonilialesOrder: Moniliales (Aureobasidium )
An example of adimorphic genus.
Conidia budbuddirectly fromhyphal cells, andbud off otherconidia, i.e.
yeast cells.
SphaeropsidalesSphaeropsidales
Conidia produced in a pycnidiumpycnidium(pl.=pycnidiapycnidia).
An asexual fruiting body. Variable in shape : globose, flask-shaped, cup-shaped, irregular or stromatic. Withostiole or not.
Variation like that of ascocarps, butproduce conidia and conidiophore.
SphaeropsidalesSphaeropsidalesPycnidia of Phoma on agar.
OstioleOstiole
PycniPycnidiumdium
ConidiaConidia
Pycnidium as seenthrough
microscope.
MelanconialesMelanconialesTwo genera of acervulusacervulus producing fungi:
Flattened stroma
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Mycelia Mycelia Sterilia Sterilia
Order in which conidia andconidiophores are not produced.
Other characteristics are utilized toclassify genera.
Often sclerotiumsclerotium stage is present andits morphology is utilized to classifythese fungi.
Mycelia Mycelia Sterilia Sterilia Sclerotium rolfsii
SclerotiumSclerotium
Mycelia Mycelia Sterilia Sterilia Rhizoctonia solani
Mycelia characteristic used todefine genus
Genetic RecombinationGenetic RecombinationMany species are thought to haveevolved away sexual reproduction.
How is this possible?How is this possible?
Shouldn’t Deuteromycota becomeextinct?
A means of genetic recombination occurs: TheThe Parasexual CycleParasexual Cycle.
Genetic RecombinationGenetic Recombination
Parasexual Cycle: Mechanismdiscovered by Pontecorvo and Roper
(1952) in septate, mycelial fungi bywhich genetic recombination is not based on sexual reproduction.
Parasexual CycleParasexual Cycle
Essential features of process:
HeterokaryonHeterokaryon formationformation
DiploidizationDiploidization
Mitotic CrossingMitotic Crossing--overover
HaploidizationHaploidization
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Parasexual CycleParasexual Cycle
Summary of Parasexual.
Parasexual CycleParasexual Cycle
Two hyphae of
the same speciesof fungi that are genetically different comeinto contact.
Parasexual CycleParasexual Cycle
HeterokaryonHeterokaryonFormationFormation:Plasmogamy of hyphal cells fromgenetically,differentindividuals.
Parasexual CycleParasexual Cycle
Diploidization:Formation ofdiploids fromkaryogamy ofnuclei.Heterozygous diploid nuclei
provide genetic recombination .
Parasexual CycleParasexual Cycle
Mitotic crossingMitotic crossingover:over: Can be seenas a more
vigorous growth inmycelium colony:Sectoring.
SectoringSectoring
Parasexual CycleParasexual Cycle
Haploidization:Thegradual reductionof chromosomenumber to thehaploid state.
Many aneuploidsfrom non-disjunctive mitosisalso generated.
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Parasexual CycleParasexual Cycle
The frequency of genetically,recombined, haploid nuclei formedwas very low.Many mycologist feel that this ismerely a laboratory phenomenon anddoes not play an important role innature.How else can we explain the successof the Deuteromycota in nature?