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.



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.



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



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



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




Summary of Parasexual.


Two hyphae of

the same speciesof fungi that are genetically different comeinto contact.


HeterokaryonHeterokaryonFormationFormation:Plasmogamy of hyphal cells fromgenetically,differentindividuals.


Diploidization:Formation ofdiploids fromkaryogamy ofnuclei.Heterozygous diploid nuclei

provide genetic recombination .


Mitotic crossingMitotic crossingover:over: Can be seenas a more

vigorous growth inmycelium colony:Sectoring.

SectoringSectoring


Haploidization:Thegradual reductionof chromosomenumber to thehaploid state.

Many aneuploidsfrom non-disjunctive mitosisalso generated.




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?

detromycetes , deutromycota hendra unesa

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