Survey of Filamentous Ascomycetes
Filamentous Ascomycetes
Plectomycetes,
Plectomycetes cleistothecium
forming ascomycetes.
Eurotiales will be used as
representative of this group.
Species decomposer of food and
textile, mycotoxin formers, etc.
Concept of anamorph,
anamorph telomorph
and holomorph.
holomorph.
Lecture 4
Order: Eurotiales
Order: Eurotiales
Life cycle of Emericella variecolor
used to introduce terms.
Sexual part of life cycle produces
cleistothecia: Ascocarp is entirely
closed (approximately 1-1.5 mm).
The cleistothecium, itself, is made up
of thick-walled hülle cells.
cells
Order: Eurotiales
Order: Eurotiales
Cleistothecium of another species of
Eurotiales from prepared slide:
Asci and ascospores of Emericella
variecolor.
StarStar-shaped
ascospore Î
Ascus with
Í Ascospores
Ascus with
Í ascospores
within
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Order: Eurotiales
The cleistothecium, with asci and
ascospores, the sexual stage of the
life cycle is telomorph.
telomorph
The asexual stage also commonly
occurs and is referred to as the
anamorph.
Order: Eurotiales
A clearer
view of
structures
from previous
slide.
Order: Eurotiales
Anamorph of Emericella (=Aspergillus)
Chains of globose
conidia borne on a
swollen vesicle.
Order: Eurotiales
Summary of
Emericella
life cycle:
Í Conidia
Asexual
cycle
° ¬ Cleistothecium
°
Mycelium
© ­
Anamorph:
Anamorph: Aspergillus
Order: Eurotiales
Penicillium,
another
common
anamorph
stage in
Eurotiales.
Telomorph:
Telomorph: Emericella
Order: Eurotiales
Illustration
of Penicillium
Phialide Î
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How can a species have two
valid names?
Anamorph + Telomorph = Holomorph
Sordaria fimicola
Paraphyses disintegrates
and is absent at maturity.
Sordaria fimicola
Asci and
ascospores. Dark
brown, with typical
eight spores/ascus.
Sordaria fimicola
An example of a
Pyrenomycete that does not
produce a stroma.
Asci and ascospores are
produced, following widening
of perithecium cavity.
Sordaria fimicola
Actual picture of
Sordaria fimicola, a much
used tools in studying
haploid genetics.
Xylariales, Xylaria polymorpha
stroma
Í
L-Section
through Xylaria
stroma:
Perithecia are
Dark oval areas.
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Xylariales, Xylaria polymorpha
Variations In Xylariales Stroma
L-Section through a
single perithecium
of Xylaria, below,
showing Asci,
ascospores and
paraphysis.
Asexual stage
with conidia
produced on
white apical
portion of
stroma.
L-Section of
Xylaria stroma,
above, with
perithecia at
periphery. Ostioles
are opened at
surface of stroma.
Variations In Xylariales Stroma
Sexual stage.
Note erumpent
areas where
perithecia occur.
Xylaria hypoxylon
Discomycetes
Hypothecium
(subhymenium).
Medullary Excipulum.
Asexual stage with conidia produced on
white apical portion of stroma.
Sexual stage. Note erumpent areas
where perithecia occur.
Variations in Apothecia
Scuttelinia, left and Sarcocypha, rights
examples of typical apothecium shape.
Ectal Excipulum:
Variable in
appearance.
L-Section through typical apothecium.
Variations in Apothecia
Saddle-shaped apothecia of Gyromitra,
left, and capitate apothecia of Leotia,
right.
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Variations in Apothecia
Variations in Apothecia
Club-shaped apothecia of Trichoglossum,
left, and pitted apothecia of Mochella,
right.
Enclosed apothecia, Tuber melanosporum,
left, and Tuber magnatum, right.
Order: Pezizales
Loculoascomycetes
Why aren’t these cleistothecia?
Members of Tuberaceae are thought to
be derived from open apothecium.
Í Hollow cupulate apothecia,
opening by a pore or slit
More complex species, folding
Í inward of excipulum occurs.
Projections fuse as in typical
Í truffle.
Bitunicate Ascus
Ascostroma is a cavity that forms in a
stroma where asci and ascospores are
borne. An ascocarp wall is absent in an
ascostroma. Compare with perithecium on
right.
Ascostroma
More difficult
to observe
endo- and
exoascus in
live material.
Note: Ascostroma does not have to be
perithecioid, in shape. Can also be
cleistothecioid or apothecioid,in
appearance.
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Ascostroma
Determination of ascostroma from an
ascocarp that is similar in appearance is
often difficult.
What are ascocarps
on right?
Uniloculate ascostroma!
ascostroma!
Thus, bitunicate ascus is generally best
way to identify Loculoascomycetes.
Phylum: Basidiomycota
Unifying
characteristic is the
production of
basidia
(sing.=basidium) and
basidiospores during
sexual cycle.
Basidiospores
Sterigmata
(sing.=Sterigma)
Phylum: Basidiomycota
Phylum as diverse as Ascomycota, but not
as many species.
Thallus again mycelial, yeast or
dimorphic.
Fruiting body, when produced, a
basidiocarp.
basidiocarp
Recent molecular data has changed
traditional concepts of phylogeny, but
not as much as in Ascomycota.
Conidia produced during asexual
reproduction.
Phylum: Basidiomycota
Recent Classification, based on
molecular data and TEM of septa, has
led to a system where there are three
classes recognized:
Basidiomycetes
Uredinomycetes (Rusts)
Ustomycetes (Smuts)
Basidium
(pl.=Basidia
(pl.=Basidia))
Phylum: Basidiomycota
A single class, Basidiomycete is
recognized, with several orders that are
segregated according to basidium
morphology:
Phylum: Basidiomycota
Unicellular, club-shaped basidium of
Agaricales and Aphyllophorales:
Agaricales,
Agaricales Aphyllophorales and
orders of “puffballs” have unicellular,
club-shaped basidium.
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Phylum: Basidiomycota
Phylum: Basidiomycota
Remaining basidium types are septate or
deeply lobed:
Order: Dacrymycetales – Tunning
fork basidium.
basidium
Order: Tremellales – Cruciate
septate basidium.
basidium
Tunning
fork
basidium
Order: Auriculariales – Transversely
septate basidium.
basidium
Variations of basidium was once believed
to be of phylogenetic significance.
Phylum: Basidiomycota
CruciateCruciateseptate
basidium
Transversely
septate
basidium
Phylum: Basidiomycota
TEM picture of
Basidiomycete
dolipore septum.
Morphology varies
in each group.
Evidence presently indicates that
members with basidiocarps closely related
regardless of basidium morphology.
Will cover
Basidiomycota:
Basidiomycetes,
Ustomycetes and
Uredinomycetes,
next week.
ÍSeptal Swelling
ÍPore
SPCÒ
SPCÒ
ÍSeptum
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