Transcript DISCOMYCETES PB 372 - GENERAL MYCOLOGY LECTURE 24 Tuesday, November 18, 2003

DISCOMYCETES
PB 372 - GENERAL MYCOLOGY
LECTURE 24
Tuesday, November 18, 2003
DISCOMYCETES
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Most have apothecial ascomata
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Hymenium is exposed at maturity
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Ascomata usually take the form of a cup or
saucer or are cushion shaped
Ascospore discharge is generally forcible
Hypogeal forms have closed ascomata,
passive discharge & dispersal by mammals
& some insects
DISCOMYCETES
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Ascomata range from minute to large &
showy
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Asci are arranged in a hymenial layer and
interspersed with paraphyses
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Asci are ovoid to cylindrical with either an
apical pore, slit or operculum
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Ascospores may be hyaline or pigmented, 0
to several septate
DISCOMYCETES
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Symbionts in lichens
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Mycorrhizal
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Endophytic in conifer associations
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Saprobes on ligno-cellulosic substrates
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Some have nematode trapping anamorphs
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Many fruit after fires
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Some are common on herbivore dung
APOTHECIUM
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Hymenium - is the layer of asci that lines
the surface or hollow part of the disc.
It is made up of club shaped or cylindrical
asci, usually with paraphyses interspersed.
Paraphyses may be as long as the asci or
shorter or longer.
The tips of the paraphyses may be
branched, knob-shaped, covered in gel
and/or united above the hymenium to form
an epithecium.
Asci &
paraphyses
in hymenial
layer.
APOTHECIUM
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The hypothecium is a thin layer of
interwoven hyphae located immediately
below the hymenium.
The excipulum is the fleshy part of the
ascoma that supports the hypothecium &
hymenium (ectal excipulum/medullary
excipulum).
The ascoma may be stalked (with stipe) or
sessile.
Excipulum Tissue Types
SYSTEMATICS
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Type of ascus dehiscence operculate or inoperculate
Ascomal development and
morphology
Staining reaction (IKI) of the
ascus tip (although not always
reliable)
RHYTISMATALES
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Produce ascomata in black stromata.
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Asci are inoperculate.
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Ascus tips may or may not blue in IKI.
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Ascospores range in shape from ovoid to
filiform; are hyaline or brown, often with a
gelatinous sheath; are often septate and
asymmetrical with the upper portion
broader than the lower portion.
tar spot of maple
Rhytisma acerina
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Causes tar spot of maple.
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Overwinters in fallen, dead maple leaves.
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Flat circular, black tar-like stromata
that bear the apothecia within them,
give the disease its name.
The surface of the mature stroma has ß
along which the stroma splits above the
apothecia each spring.
Rhytisma acerina
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When the stroma splits open, long needleshaped ascospores, each with a gelatinous
sheath are released in great numbers from
the apothecia by a puffing action that
liberates visible clouds of spores to be
picked up by air currents and dispersed.
After reaching a susceptible host, the
ascospores adhere to the underside of the
leaf by their sheath and germinate by
germ tubes.
Rhytisma acerina
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Mycelium of R. acerina grows
within the upper epidermal cells
and forms compact hyphal
masses that form the ascomata
primordia.
See the handout for further
details of development.
CYTTARIALES
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Sole genus of the order, Cyttaria, is known
only from species of Nothofagus, the
Southern Hemisphere beech, and is found
in southern S.A., Australia and New
Zealand.
The bright orange or yellow fleshy
stromata of Cyttaria are edible and eggyolk to golf-ball sized stromata are
regularly sold in markets in southern Chile.
CYTTARIA
Ascomata embedded in fleshy,
globose stromata produced in large
clusters that fuse secondarily.
 Asci have a wide amyloid (IKI+) pore.
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Cyttaria
Cyttaria
Cyttaria
Cyttaria
LEOTIALES (HELOTIALES)
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Cup, disc, or tongue-shaped apothecia
Asci inoperculate, with a pore and only
slightly thickened at the apex
Ascospores may be septate and can be
round, elliptical, elongated, or more rarely,
thread-like
Saprobic on soil, dead wood, dung, plant
debris; parasitic on plants
Approximately 10 families
Sclerotinia (Monilinia)
fructicola
Sclerotinia (Monilinia)
fructicola
http://biologi.uio.no/bot/ascomy
cetes/Taxa/Sclerotinia.html
Sclerotinia
tetrasporum
http://biologi.uio.no/bot/ascom
ycetes/Taxa/Sclerotinia.html
Sclerotium
Mitrula (Geoglossaceae)
Leotium (Leotiaceae)
Aquadiscula
PEZIZALES
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Large order that contains operculate
discomycetes as well as derived hypogeous
forms that have evanescent asci with
ascospores spread by mycophagy
Most are saprobic, living on dead wood, soil
or humus; a number of species are
ectomycorrhizal.
http://www.herbaria.harvard.edu/discomyc
etes/
Pyronema (Pezizales)
Pyronema (Pezizales)
Pyronema (Pezizales)
Pyronema (Pezizales)
Pezizales
Pezizales
operculate asci
Pezizales
Peziza
Peziza
Sarcocypha coccinea
Sarcocypha coccinea
Urnula (Devil’s Cup)
Morchella esculenta
Morchella
Morchella
Giant Morel
Gyromitra (false morel)
Tuber melanosporum
(truffle)
Tuber - asci and ascospores
Stephensia shanori (local
truffle)
La femme, tes
truffes, et ton
jardin,
garde-les bien de
ton voisin.
DISCOMYCETES
Rhytismatales - Rhytismataceae - Rhytisma
Helotiales
Sclerotiniaceae - Monilinia, Sclerotinia
Geoglossaceae - Geoglossum (earth
tongues)
Pezizales
Pezizaceae - Pyronema, Peziza,
Ascobolus
Sarcocyphaceae - Sarcocypha, Urnula
Morchellaceae - Morchella
Helvellaceae - Verpa, Helvella,