无效的SQL语句: insert into `kwd` set keyword='韩国演艺圈悲惨37好看'
Mysql error description: Duplicate entry '' for key 'PRIMARY'
Mysql error number: 1062
Script: http://www.9wo.cc//
Referer: http://www.9wo.cc//Ascomycota, Ascomycetes & Sac Fungi
&ascomycetes.htm&
&Index to Mycology&
The Basics
Mycology & The Fungi
For educational
quote cited references only:--
True Fungi (Eumycophyta<span style='color:#
Ascomycota (Ascomycetes, Ascomycotina)
-- Sac Fungi
Sub-Class; Series:
Plectomycetes
illustrations to enlarge
All members of the Ascomycota produce an that contains .
The class includes the largest group and
most successful of all fungi, with over 44,000 known species.
The group has existed for many millions of
years and there is some evidence that they took their origin from
Zygomycotous forms.
The Ascomycota
are highly important in the break down of organic matter in the soil, as
plant pathogens and for the production of antibiotics and other industrial
substances.
Many species are purely
some are obligate parasites and others facultatively saprophytic
or parasitic.
Most species have a
well-developed septate mycelium, and septations contain a septal pore or perforate septum.
Cells primarily have only a single nucleus per cell but there
are some with more than one nucleus per cell.
Those species known as yeasts are distinguished by not
forming mycelia and individual cells multiply by fission or budding
processes.
The yeasts are not primitive
organisms but special forms that evolved from a retrogressive process in
evolution.
A large proportion of the Ascomycetes have one or more
means of vegetative reproduction.
This imperfect stage produces conidia but never any zygospores.
The perfect or sexual stage produces asci,
which is the cardinal feature of the entire class.
The production of asci terminates the relatively complicated
sexual process.
Asci occur in a spore
sac, which may take various shapes.
The number of ascospores is variable, but 8 per ascus
are typical in 98 percent of species.
Typically, ascospores are forcibly discharged (sporangiospores are
The ascus is the seat of
meiosis, which is not true in sporangia.
In 99 percent of cases the ascus is also the site of nuclear fusion.
In contrast to sporangiospore formation by progressive
cleavage, ascospores are delimited in a process known as &Free-cell Formation&.
This results in a leaving of cytoplasm in
the ascus, which is called .
Ascospores are almost always uninucleate
(haploid with a single nucleus per spore), but the genus Neurospora is
an exception with 2-4 nuclei per spore.
The epiplasm largely disappears when the ascospores mature, which
suggests that it serves to nurture the spores.
ascus develops there is a large 2N nucleus that divides to form 8
These nuclei develop
Cytoplasmic radiations form
walls around each nucleus thereby delimiting ascospores.
Fruiting bodies () whose walls
consist of closely interwoven hyphae may form various shapes.
In contract there are no fruiting bodies
in the Zygomycota.
all of the Ascomycota produce fruiting bodies.
There are none in the small sub-class Hemiascomycetes while all
members of the much larger subclass Euascomycetes produce fruiting bodies (=
ascocarps).
Please refer to the
following plates for characteristic structures in the Ascomycota:
Ascomycota
Plate 102Phyllosticta,
Dendrophoma, Monopodium, Verticillium, Aspergillus,
Penicillium &
Isariopsis.
Septoria, Marssonia, Epicoccum & Arthrobotryum.
Pyronema omphalodes.
Globose, Ovate, Septate, Clavate, Cylindrical.
Gelasinospora autosteira
Two discussed orders in the
are: Endomycetales & Taphrinales Three families in the order Endomycetales
Ascoidaceae, Endomycetaceae
& Spermophtoraceae.
The Here the mycelium consists of multinucleate cells and thee is no
imperfect stage.
Asci are formed as
Two gametangia arise on adjacent cells and nuclei
migrate to gametangia where crosswalls are formed.
The female portion usually enlarges and gametangia
The fusion cell enlarges into a
sac, which is a transformed fused gametangium with many nuclei.
Fusion nuclei fuse but others disintegrate.
Meiosis takes place to produce many
Ascospores are delimited from
each of the many nuclei.
The family All species form asci as a result of
but there is only a single nucleus per
gametangium.
Gametangia fuse and the
nuclei fuse to produce one diploid nucleus.
Meiosis occurs and the number of spores varies between 4 and 8.
There is no degeneration of the nuclei and
the duration of the 2N nucleus is short except in Saccharomyces cerevisiae.
Various species show distinct behaviors.
In the Genus there is only a perfect stage.
has an imperfect stage
In this species arthrospores
are formed by disarticulation of hyphal cells.
The process begins at the apex of hypha that have stopped
growing and continues posteriorly.
Arthrospores germinate directly or they may form crosswalls and
multiply by fission.
In blastospores
are formed in a budding process.
blastospore gives rise to hypha that may produce secondary blastospores and
are thus difficult to distinguish from yeasts.
and Saccharomyces are yeasts that grow primarily in
single-celled form.
They multiply by
In Schizosaccharomyces asci
formation occurs when two cells come together (gametangia), fusion occurs and
eight ascospores are delimited in one ascus.
a budding yeast, and S. cerevisiae is one of the most important
species that is used for rising bread.
There are individual cells and multiplication is accomplished by the
formation of buds.
A single nucleus
divides with one nucleus going to the bud.
In the sexual stage every vegetative cell under the right conditions
can form ascospores within, and typically four are delimited.
This process appears to be parthenogenetic
but it is not.
Details on
Characteristics of Yeasts
Yeasts are not
regarded as primitive and they multiply either by fission or budding.
The many different types are distinguished
as being sporogenous (produce asci), asporagenous (do not produce asci as in
the Deuteromycota), haplobiontic, budding, apiculate, ,
film-forming, oxidative, diplobiontic, illegitimate diploid and multipolar.
A typical yeast
A septum separates the cell, and a cell
may function as a gametangium, which fuse to form an ascus.
Fusion of nuclei occurs in the developing
ascus, and meiosis follows to produce 8 haploid nuclei.
An example of a (multipolar)
yeast is .
It is intermediate between haplobiontic and diplobiontic and budding is the
process of multiplication.
multipolar budding type where a bud may appear on any side of the cell.
Diploid cells result from the budding
process after fusion of &A& and &B& asci.
Four ascospores are delimited in a cell
Ascospores multiply by a budding process, but are
haploid and much smaller than the diploid cells.
Under ordinary circumstances two of the haploid cells come
together and fuse.
Half of the
ascospores in an ascus are of the &A& Type and half of the &B&
When two or one types fuse the
result is an &.&
The budding of fused ascospores produces
diploid cells:
S. cerevisiae is of great importance because
under conditions of low aeration it can produce alcohol without the
intervention of Oxygen, even though the yeast cells will not grow.
-----------&#9658; CO2 + C2H5OH
Various strains are used in the fermentation of beer,
wine, etc.
The most tolerant strains
will not tolerate more than 13-15 percent alcohol.
Taxes from the sale of alcohol can surpass 6 billion dollars
per year in North America, and the baking industry uses yeast for leavening
and carbon dioxide.
An estimated 300
tons of yeast cake is used daily in North America
If Oxygen is present, the reaction will be:
-----------&#9658; CO2 + H2O
The medium
is acidified and aerated to stimulate rapid multiplication.
In about 12 hours the yeast will multiply
to five times its original volume.
Yeasts cannot use starch so they must have sugar.
Sugar sources are usually molasses or
grain mash (acid hydrolysis or enzyme or another microorganism breaks down
the starch into sugar).
Yeasts are rich in protein and there is a possibility
of using sawdust, etc. as a food source for yeasts, which are substituted for
high protein diets.
extensively used for livestock.
Yeasts also are high in Vitamin B complexes and Vitamin D
(Ergosterol).
yeasts are
exemplified by the Genus ,
which is found on ripening fruits (apple, grapes).
They may also occur on dust, leaves in the soil, etc.
These yeasts multiply in the juice and
carry on a kind of fermentation that is known as &Spontaneous Generation Fermentation.&
However, the alcohol content produced is
low, in the range of 5-6 percent.
the commercial production of wine, the juice is first sterilized and then
inoculated with a desired strain of yeast.
The insect Genus Drosophila feeds mainly on the yeasts although
the initial attraction may involve the alcohol.
The apiculate yeasts bud only at the poles and are thus
&bipolar.&
The Genus typifies
film-forming yeasts.
elongated cells in a chain known as a pseudomycelium.
They occur on the surface of liquids such
as pickle brine and are poor in the ability to carry on alcoholic
fermentation.
In some cases they may
actually be .
Characteristics of the family Spermophthoraceae There is a
mycelium and some species are the cause of &Cotton Stigmatomycosis,& which damages the
cotton boll.
The Genus Nematospora
is single-celled and causes &.&
All these genera produce Rhiboflavin in large amounts.
Eremothecium exceeds all others in
production, but following the placing of a patent, several strains of Ashbya
have been found that almost equal it in production.
Ascomycota:
Endomycetales
sp. & Endomycopsis sp.
Schizosaccharomyces
octosporus
Saccharomyces
cerevisiae; & Structures of Hanseniaspora sp., Pichia sp.
Endomycetales:
Endomyces sp., Schizosaccharomyces
octosporus &
Endomycopsis sp.
Endomycetales:
Saccharomyces
sp. & Ashbya gossypii.
Taphrinaceae and Protomycetaceae.
Asci arise from a proascus, not from two gametangia as in the
Endomycetales.
No fruiting bodies are
The family Taphrina deformans causes
&&, T. communis
and T. pruni cause &.&
Also various species of Taphrina
occur on many wild hosts of which about one-third are pathogens on ferns.
A naked layer, ,
bears asci on the surface.
be subcuticular, breaking the host cuticle on emergence or they may reside in
the epidermal cell interspaces.
arises from a .
The mycelium is intercellular (= &High Type& parasite) and there are no
haustoria.
All cells have two nuclei
(= ), and this is
the only place in all the Ascomycota where this occurs. In the Basidiomycota
a dikaryoti thus, the similarity.
Ascospore budding may begin inside the
ascus, which resembles a yeast on agar (Saccharomyces).
exemplifies
the family.
Hyphae accumulate
underneath the host cuticle and are called proasci.
Nuclei fuse in the proascus to give a diploid
condition.
The diploid cell pushes up through the host cuticle and
forms a crosswall.
The bottom cell is
now the && and the top one the
Meiosis occurs
in the ascus and subsequent mitotic divisions produce an ascus with 8 haploid
Each nucleus forms an ascospore and these may be
forcibly discharged from the ascus.
The ascospores
bud until reaching an optimum substrate, where they stop budding and send out
a germ tube between the epidermal cells.
Hyphae may occur throughout the leaf tissue.
deformans is a homothallic organism and there is no imperfect stage.
There are at least two heterothallic
species of Taphrina in Europe.
In this case &A& and &B& ascospores are
and &B& ascospores fuse and
&A & B& nucleus is formed.
Other differences among the species of Taphrina
may include the presence of foot cells, and the size of the ascus varies
(e.g., T. coerulescens are very large).
Budding may also occur in the ascus.
Taphrina species may affect the host by causing
hypertrophy with or without hyperplasia (e.g., ferns show little
hypertrophy).
There may be a failure
of tissue differentiation as in the case of the disease known as &Plum
The family These are plant invaders that incite gall
production on ragweed.
Thick-walled
cells arise on the mycelium (= proasci).
Intervening
hyphae break down leaving only the proasci.
These are located down in the plant tissue.
Ascospores bud on being released from the ascus.
However, there is some doubt as to whether
or not these are proasci.
Cytological
behavior in the &ascus& is quite unlike that of other members of
the Ascomycota.
Please refer to the following plates for characteristic
structures and Life Cycles in the Taphrinales:
Ascomycota:
Taphrinales
deformans &Peach Leaf Curl.&
Taphrina spp.
Ascomycota:
Taphrinales
In the Sub-Class,
Series: three orders discussed
Plectascales, Myriangiales and
Erysiphales.
In the Series:
Pyrenomycetes seven orders discussed are Hypocreales, Sphaeriales,
Pseudosphaeriales, Dothideales, Hemisphaeriales, Laboulbeniales and
Hysteriales.
In the Series:
Discomycetes four orders are Helotiales, Lecanorales, Pezizales and
Tuberales.
The Euascomycetes show different developmental
patterns, but are generally similar throughout.
Asci are produced in aggregates and formed in connection with a
fruiting body, the ascocarp.
process involving a female ascogonium and a male antheridium or spermatium
initiates asci formation.
Gametangia
fuse followed by a transfer of nuclear material to the ascogonium.
The ascogonium gives rise to ascogenous
hyphae in which nuclei are paired (= dikaryon).
Conjugate nuclear division is carried out in the ascogenous
hyphae and these hyphae re dikaryotic.
A ascogenous hypha branch bends over in a crozier.
Three kinds of cells are formed:
(1) ultimate, (2) penultimate and
(3) antepenultimate.
The penultimate cell becomes the ascus.
The ultimate cell
may fuse with the antepenultimate cell to form a dikaryon and another
This may then form another
Sterile hyphae are induced to grow and branch
underneath the sexual structure.
These sterile structures either form the main part of the ascocarp or
the system of ascogenous hyphae may simply give rise to a structure of
sterile hyphae below the sexual structures, which is still an ascocarp,
Three types of
ascocarps are found in the three respective groups of the Euascomycetes, or
series ().
In the Family These are karotinophilic fungi that grow
on feathers, hair, hoofs, nails, maize, etc.
They are similar to Dermophytes in the Deuteromycota, and they can
produce a mild skin disease in humans that is not as serious as in the
Deuteromyccota.
They have a where the hyphae are racquet-shaped.
Two kinds of vegetative reproduction are by conidia or
chlamydospores.
The conidia occur in
long chains at the ends of branched or unbranched conidiophores.
The Deuteromycota have a genus Paescilomyces
that produces conidia in the same manner.
During sexual
reproduction antheridia and ascogonia fuse.
Ascogenous hyphae branch out from the ascogonium and the ascus forms
as a result of crozier formation from the ascogenous hyphae.
Many asci are produced, which are
typically naked, each with 8 ascospores.
There is no real ascocarp although there may be a weak suggestion of
In the Genus Gymnoascus a sexual process initiates the
building the building up of a weak wall, and spines occur on the tips of
swelled hyphae.
These are considered
to be a &weft of specialized hyphae.&
Characteristics of Euascomycetes
Asci are clustered and borne in a fructification
(ascocarp).
The asci are formed in
connection with an ascogenous hyphal system.
Ascogenous hyphae arise as outgrowths of an ascogonium.
Nuclei pass from an antheridium to an
ascogonium but do not fuse.
conjugate nuclear division increases each nucleus respective to set up a
dikaryotic phase in the ascogenous hyphal system.
The dikaryophase is ended when the asci form, which involves a
Classification of the groups (series) is based on the
form of the ascocarp, the form of the asci and the distribution of asci in
the ascocarp.
The Plectomycetes have
a closed fructification (),
scattered asci and globular asci.
Pyrenomycetes have a flask-shaped fructification (),
asci occur in a definite layer (hymenium) and they are elongated.
The Discomycetes have an open
fructification (), asci occur in a
definite layer and they are also elongated.
The order Plectascales is the most characteristic order
in the group.
Most ascocarps are very
small although the family Elaphomycetaceae is an exception (some doubt about
its classification).
The family Gymnoascaceae has poorly developed ascocarps
(thin wefts of hyphae), but all other typical features of Euascomycetes are
A scattered group of more or
less globular asci each containing from 6-8 spores is formed.
The genus Byssochlamys has
relatively undeveloped ascocarps.
family also has karytinophilis forms.
It is related to a group of Fungi Imperfecti (Dermatophytes) ecause of
the peculiarity of the racquet mycelium.
The family The asci are
globular, scattered in the ascocarp with 8 ascospores per ascus, and thus are
similar to the Gymnoascaceae.
The Genus has
a characteristic pattern in the conidial stage.
A conidiophore arises anywhere on the mycelium and forms a
bulbous structure at its apex (= vesicle).
Sterigmata are formed, and conidia are produced in chains at the ends
of the sterigmata.
Sometimes there
are secondary sterigmata also.
Similar forms in the Fungi Imperfecti bear the name Aspergillus,
but they never possess the added names of Eurotium, Emericella,
and Sartorya.
Members of the genus possess the ability to grow where
there is a high osmotic concentration (high sugar, salt, etc.).
Species that best represent the genus are Aspergillus
ametelodami, with both sexua and Aspergillus
niger, A. fumigatus and A. flavus that do not have a
perfect stage.
Examples of species with economic importance are Aspergillus
alliaceus (Bulb Rot of Onion), A. flavus (starch-digesting
enzyme), A. fumigatus (causes Aspergillosis), A. niger
(produces citric acid.)
The Genus is a companion genus of Aspergillus, both occurring in the
However, Penicillium exceeds
Aspergillus in abundance.
ascocarpic stage is similar to Aspergillus, but the conidial stage
Here conidiophores do not
form a vesicle, instead a of where
there are three types ().
The structure bearing the chains of
conidia are called sterigmata.
The abundance of Penicillium spp. In nature is
extensive.
They are primarily
saprophytic forms and plan an important role in the breakdown of organic
They also may spoil many
foodstuffs.
There is no perfect
Penicillium chrysogenum
secretes penicillin.
It acts on
gram-positive organisms, which are very common in nature.
Although other species also produce
antibiotics, P. chrysogenum is widely used for antibiotics production
due to its secretions being low mammalian toxicity.
Other species are P. expansum (Apple Rot), P.
digitatum and P. italicum (Citrus Fruit Rot), P. roqueforti
(Blue Cheeses).
occurs in the soil and was once erroneously thought to be pathogenic
on tobacco.
The disease
&Thielaviopsis& was actually caused by one of the Fungi
Imperfecti.
Ascocarps are similar to Aspergillus
and Penicillium, but they are dark and football shaped.
The ascospores spill out into the cavity
of the cleistothecium and the ascus is evanescent.
the disease &.&
This name was derived from a misjudgment
as it was once believed that the scattered ascospores occurred in one large
The family
They are the size
of a hickory nut and hypogenous.
are associated with tree roots and believed to be a mycorrhizal fungus by occurring
on tree roots.
The Genus Elaphomyces may actually be a highly modified
Discomycete.
Ascomycota:
Plectascales
Aspergillus sp.
Penicillium
thomii, P. lanoso-coeruleum & P. wortmanni.
Byssochlamys sp.
Aspergillaceae:
Penicillium
vermiculatum
Aspergillaceae:
Aspergillus
is no typical cleistothecium.
in the genus are parasitic on
scale insects.
They build a dense
mass of compacted hyphae (stroma), which flatten out to form capsules.
The whole structure is stromatic.
The asci are borne scattered in the
The ascospores are muriform
where multicellular spores appear as bricks in a wall.
The Genus also
has a stromatic form.
Ascospores are
scattered through an undifferentiated stromatic layer.
The genus includes pathogens of cultivated
plants and causes &&
especially in tropical regions.
imperfect stages is referred to as &Sphaceloma.
A stroma appears as a layer on or under
the host epidermis.
Ascospores are
not muriform but are simply divided by a few crosswalls.
Ascomycota:
Myriangiales
Elsinoe sp.
Aspergillus
amstelodami, Penicillium Byssochlamys
Aspergillus fumigatus, Byssochlamys nivea,
Elaphomyces
sp., Elsinoe wisconsinensis, Monascus sp., Myriangium sp.
,The mycelium is largely, if not entirely,
confined to the surface of the suscept organ involved and may be either white
or dark colored.
There are both
obligate parasites, as in the Erysiphaceae, or forms merely growing as
saprophytes on honeydew that is deposited by insects.
The ascocarps are mostly cleistothecia.
The family ErysiphaceaeAll are common parasites.
The mycelium is primarily superficial on leaves, stems and even fruit,
but may be internal also.
anchor the mycelium to epithelial cells, which forms a whitish powdery mass
with profusion of conidia.
mycelium is composed of short, uninucleate cells, and the haustoria are
bulbous usually with a single nucleus.
They may be elongated or they may even occur uncommonly in the subepidermal
layer. The Meliolaceae and Capnodiaceae have a dark superficial mycelium, and
these forms are common in the tropics.
The Erysiphaceae incite a great variety of diseases of
cultivated and wild plants.
industry in France was threatened before with the surge of the Downy Mildews
(Zygomycota).
Dusting with sulfur
onto the vines successfully controlled the infection that was the first
successful use of a fungicide.
humid areas the powdery mildews may be reduced by moisture on the leaf
The Genus is only one of the six common genera in North America.
It has both a superficial and an internal
There is no form with only
an internal mycelium.
There is an Oidium Imperfect Stage, where the fungus
bears unbranched, upright conidiophores with catenulate conidia.
The conidiophore typically has only one nucleus.
The nucleus keeps dividing in the
conidiophore and migrates to the terminus to form a new conidium with an
indefinite number of conidia.
species the conidia are seldom found in long chains (e.g., Clover
Spores are carried by wind
to a new host where they may germinate without water being present.
This explains why powdery mildews thrive
under dry conditions.
Spraying with
water may even control these fungi.
The Ascocarpic Stage has a diagrammatic cleistothecia
with a well-defined wall of interwoven hyphae.
The color is usually dark.
Appendages grow out from the outside layer.
A delicate inner layer is present and there is usually
only one ascus inside the ascocarp with less than 8 ascospores.
Although there were originally also 8
nuclei the others disintegrate.
Alternatively there may be several asci in a hymenium.
Ascocarps are the overwintering structures and they are
produced in abundance toward the end of the growing season of plants.
The cleistohecium may explode in the
spring followed by an explosion of the asci, which aides in scattering the
Taxonomy is based on
appendages and the number of asci per ascocarp as is shown in Fig 292:
The Genus has
a Perfect Stage with distinctive characteristics.
Many speci and an ascogonium and
antheridium are each produced on separate hyphae.
Each possesses a single nucleus.
The male nucleus passes into the ascogonium through a
pore to form the dikaryophase.
ascocarpic wall begins to form by sterile hyphae moving out from either adjacent
cells, the ascogonium or even the antheridium.
This process begins before fusion of nuclei (karyogamy).
As the cell grows it digests the hyphae that are in the
interior of the fructification.
hyphae are the .
There are eight nuclei in the ascospore,
but not all may develop into ascospores.
When more than one ascus is delimited, the ascogonium
has previously sent out a system of ascogenous hyphae.
The families
They are not closely related to the Erysiphaceae
and are uncommon in North America, being rather more tropical in
distribution.
Information about them
is scanty.
The mycelium is largely
superficial but there may be a partial internal mycelium that produces
haustoria.
The mycelium is always
dark in color.
There are no obligate
parasites and some species even grow as saprophytes on insect honeydew.
When on fruit they can disfigure the
Meliolaceae is the most
important family of sooty molds and is one of the most common maladies in
tropical areas.
The term &Sooty Molds& may also be applied to
other fungal groups as well.
North-central North America the most prevalent &sooty mold& is a Pyrenomycete
Key To The Common Genera of Erysiphaceae
(Plate 200)
Please refer to
the following plates for characteristic structures and Life Cycles in the Erysiphales
Ascomycota:
Erysiphales
Host cells & mycelia relationships.
Taxonomic characteristics.
Spaerotheca sp.
In the Sub-Class Euascomycetes, the Series Pyrenomycetes is a large group with few stable,
ordinal characteristics.
classification has been in a continuous state of flux with various new
alignments being proposed.
changes which have been suggested from time to time originate from the
continuing attempt to make classification of the fungi as natural as
possible.They produce perithecia or perithecia-like hyphae.
A perithecium possesses a peridium while
the &perithecium-like& forms are without such a peridium.
The ostiole is an opening in the
perithecium.
Among the gametes the female is the ascogonium and the
male the antheridium or spermogonium.
The spermogonium produces small, uninucleate cells at its base, which
are termed spermatia.
These will
generally not germinate but act rather as non-motile male gametes.
Inside the
perithecium there may occur two kinds of elongated asci.
Most asci are initiated by crozier formation, and they are always
formed at the base of the perithecium as a hymenium.
Sterile hyphae will often project between
the asci on the hymenium.
vary in shape and length.
Others may
occur just under the ostiole and project into the opening.
The basal structures are termed paraphyses
and the apical ones periphyses.
Pseudoparaphyses are sterile hyphae that are joined to the perithecial
wall basally and apically.
Two stages that occur generally in the Pyrenomycetes
are a perfect one that allows for a recombination of characteristics, and an
imperfect one, which does not allow for character combination.
Two orders in the Pyrenomycetes, Huypoceales and
Sphaeriales, constitute the &core& of the Pyrenomycetes.
Previously the genera of both of these
orders have been classified on the basis of the color of their ascocarps, and
so they will be treated here:
Hypocreales = bright- soft, waxy,
rarely brittle.
Sphaeriales = black
leathery and brittle.
This is an old order
that some authorities have contended should be merged with the
Sphaeriales.
Generally the members of
these two groups are basically much alike.
They have been segregated primarily on the basis of what some feel are
unimportant characters:
principally
differences in the color and texture of the ascocarps.
The Sphaerailes as traditionally defined
have ascocarps that are brown to black and carbonaceous to leathery in
Morphologically similar
forms with softer, bright-colored fructifications have been assigned to the
Hypocreales.
In both orders the
ascocarp is an ostiolate perithecium and in either the perithecia may be
borne singly on the mycelium or they may be produced in dense clusters,
seated upon or imbedded within a stroma.
In the latter case the color and texture of the stroma are usually
similar to that of the perithecial walls.
Whatever the groupings are there is in the large assemblage of forms
producing dark and bright-colored true perithecia the core group of the
Pyrenomycetes. The perithecium is typically flask-shaped with a
well-developed peridium.
found grouped or distributed over the mycelium.
Elongated asci are usually cylindrical, which at maturity
contain 8 ascospores arranged linearly inside the asci.
At maturity of the ascospores the neck of
the perithecium becomes dark.
Here there are simple
conidiophores and the conidia are suspended in a drop of slime at the apex of
the conidiophore:
Perithecia may
be borne singly on the mycelium or in a stroma.
The family
Species of the Genus are saprophytes on twigs and branches although some are also
parasitic.
The mycelium is
distributed over the host bark and small patches of stroma form under the
bark surface.
The bark ruptures, exposing orange, cushion-shaped
The Fusarium Imperfect
Stage forms on top of the stroma.
Perithecia
develop on the stroma at the end of summer, with the youngest perithecia
appearing at the apex.
completely cover the stroma.
Pseudoparaphyses
occur in the perithecium.
contain 8, two-celled ascospores with a shape similar to Hypomyces.
The family
existence of intermediate forms makes separation on this basis difficult.
The Genus Hypomyces contain species that are parasites
of gill fungi (Agaricales).
gills fail to develop and there is a distortion of tissue.
A stroma completely covers the host with a
thin, orange-colored layer.
Perithecia are embedded in the stroma with their necks
projecting.
The ascospores are
two-celled.
The conidia that are
produced by the Fusarium Imperfect Stage show much variation in size,
shape, number of nuclei, etc.
The family A fascile, or bundle, of filamentous ascospores is
In many species crosswalls
may come in so that each ascospore may contain up to 150 cells.
Paraphyses disintegrate before the
ascospores mature.
The Genus has
over 200 species most of them parasitic on insects.
Coremia are usually found in the Imperfect Stage (Isaria
Erect, clavate or stalked
perithecial stromata also grow out from the mummified insect. When parasitic
on Elaphomyces an easy to locate the hypogenal ascocarps is to view
the brightly colored stromata that appear on the ground surface.
Perithecia occur
on the periphery of the stroma.
The larvae of
the June beetle are attacked and mummification ensues.
Perithecia
develop on the periphery of an apical club sent up from the host, but not all
stroma are club shaped here.
In the Isaria Imperfect Stage a pyramid
of hyphae with condiiophores branch off.
causes of rye,
wheat and wild grasses.
A mycelium
becomes established in the ovary of the host and may actually replace the
This mycelium will form a
highly convoluted stroma that will be slightly projected out of the ovary
Conidia are borne on this
&mycelium& and they are mixed with a sticky, sweet, nectar-like
secretion, which is attractive to insect vectors.
The mycelial mat hardens into a stroma, which takes a
spur-like form or a &.&
slightly longer than the grain pieces that it assimilates.
These drop to the ground in autumn and form the
overwintering stage.
In the spring
these sclerotia will germinate and send out tubes that form a stroma at their
apices, which in turn bears the perithecia.
The ascospores may be one-or two-celled.
With regards to the spur produced as the overwinter
stage, a toxic alkaloid is produced within, which causes a disease of humans
and animals called .
It causes constriction of the blood
vessels and results in a dropping-off of the extremities.
Spurs also produce the drug called Ergotin, which has been used in medicine to contract
the uterine muscles after childbirth.
The Genus causes
Some species are also parasitic on
A mycelium forms a stroma,
which extends around the stem.
perithecia are embedded in the stroma with their necks extruded.
In the conidia are densely packed on a stroma.
The Genus has
pink ascospores and a Fusarium Imperfect Stage.
The mycelium may or may not produce a
Dark blue perithecia are
produced singly and scattered over the stroma or mycelium. Gibberella zeae and closely related
species are important pathogens on cereals, inciting various rots.
Gibberella
fugihuroi was found to cause rice plants to grow up to
twice the size of normal plants.
took place without a distortion of tissues.
It is believed that this enlargement is due to both hyperplasia and
hypertrophy of the host tissue, but occurring evenly and without
distortion.
The research was
developed in Japan but halted during World War II.
A mixture of compounds is involved, and it is very effective at
1 ppm. on some host species.
genetic deficiency may be masked by applying the chemicals, as in the case of
dwarf peas returning to normal size and bush beans to pole beans.
Please refer to
the following plates for characteristic structures and Life Cycles in the Hypocreales:
Ascomycota:
Hypocreales
Nectria sinnabarina
Claviceps purpurea
Pyrenomycetes:
Hypocreales:
Claviceps, Cordyceps,
Epichloe, Gibberella,
Hypomyces, Nectria, Neocosmospora
Hypomyces, Nectria, Neocosmospora
purpurea, Gibberella zeae, Cordyceps
agariciformistyphina
Bibliography