2. GENERALCHARACTERISTICS:
• Members ,belonging to this class of Fungi, possess septate
mycelium and reproduce by means of asexual
spores(conidia) only.
• Hence the name “fungi imperfecti”(fungi that lack a perfect
or the sexual stage).
• Except the unicellular yeast-like members of blastomycetes,
almost all the remaining deuteromycotina have a true
mycelium,consisting of well-developed, well-branched,
septate hyphae.
3. • The mycelium is usually intercellular or intracellular, and
each cell contains many nuclei.
• The septa of all the species resemble largely that of
Ascomycotina. A simple central pore is present in each
septum.
• Sexual reproduction is completely absent.
• Reproduction takes place chiefly by the formation of special
asexual spores called conidia.
• The conidia are non-motile structures which develop
exogenously on the conidiophores, and therefore
deuteromycotina resemble ascomycotina.
4. • The conidia are highly variable in shape, size, colour etc.
• They are hyaline or variously coloured, unicellular or
multicellular, and transversely septate or contain both
transverse as well as longitudinal septa.
• They may be oval, elongated, spherical, star-shaped, curved,
threadlike, disc-shaped, coiled, and of other shape.
• The conidia are produced either directly on the
conidiophores or in some special types of fruiting bodies
such as synnemota, acervuli, sporodochia or pycnidia.
5. • These fruiting bodies are
pseudo-parenchymatous
structures within which, or
on which ,conidia are
produced.
• Sutton(1973) recognized
only three types of the
fruiting bodies, viz.,
pycnidia, acervuli, and
stromata.
7. PARASEXUAL CYCLE
• It is a process in which plasmogamy, karyogamy and
haploidization takes place, but not in particular place in the
thallus nor at any specific period during its life cycle.
• FORMATION OF HETEROKARYOTIC MYCELIUM:
Heterokaryon formation refers to the condition by which
genetically different nuclei are associated in a common
cytoplasm.
8. • OCCASIONAL KARYOGAMY:
Following initial fusion of hyphal cells, to form a genetically
different cell, mitotic division perpetuates the cell and
mycelium that is made up of genetically, different nuclei is
formed.
• HAPLOIDIZATION:
This haploidization is NOT meiosis.
It is in fact, a series of errors in mitosis.
A sequential loss of chromosomes will eventually give rise
to a haploid nucleus.
9.
10. EXAMPLES OF DEUTEROMYCOTINA
• Aspergillus niger
causes black mold;common food contaminant
• Trichophyton sp.
causes athlete's foot
• Penicillium notatum
source of penicillin
12. CLASS HYPHOMYCETES
• Hyphomycetes are asexual reproductive structures produced
directly on their substrate without any kind of enclosing tissues.
• The most common function of hyphomycetes is reproduction and
dispersal, although in some species the conidia may act as
gametes or "spermatia" that can fertilize an incipient dikaryon.
• Hyphomycetes come in a staggering variety of forms.
• This immense diversity reflects the role these forms play in the
dispersal of the fungus producing them.
13. • Each species grows in a particular habitat.
• When the nutrients in this habitat are exhausted the fungus
must ensure that its offspring find their way to a similar
source of nutrition.
• Getting their conidia to this new place, often a very small
target, requires precise dispersal mechanisms.
• Dispersal mechanisms includes:
-Air dispersal
-Water dispersal
-Dispersal by insects and small other animals.
14. AIR DISPERSAL:
-Epicoccum nigrum and Nigrospora
sphaerica, are examples of fungi that
actually propel their conidia into the
air using mechanisms that force the
conidium away from its subtending
cell.
• The large black conidium is still
attached to its cell awaiting lift-off.
• There are two cells that have
already discharged their conidia.
• The tube that directed water
pressure up against the bottom of
the conidium, shooting it away.
15. • WATER DISPERSAL:
Many hyphomycetes are dispersed
by water rather than air. Some of
these species actually live out their
lives in water while others only use
water as a means of dispersing their
conidia.
Fungi often grow in habitats that
are periodically flooded but are
usually dry. When water levels rise
the conidia are able to float away.
These conidia are not as likely to
trap air but will become attached to
bubbles of foam.
Conidia of aquatic hyphomycetes are
easy to collect and observe under the
microscope. They often collect and
concentrate in the foam of running
streams.
16. Dispersal by insects and small animals:
• Air currents do not dislodge the
conidia nor are they likely to come
in contact with water.
• Instead they stick to the bodies of
insects and mites that are moving
about in their habitat.
• The conidia are sticky because of
the liquid they are borne in.
Eventually the animal will move on
to a new habitat and the fungus
with be rubbed off and begin to
grow there.
17. • The class hphomycetes is classified into 4 orders based on
the presence or absence of conidia and degree of the
aggregation of the conidiophores into specialized structures
called synnetama.
• Orders:
• Hyphomycetales
• Stilbellables
• Tuberculariales
• Agonomycetales
18. • The disease caused by
hyphomycetes is called as
HYALOHYPHOMYCOSIS. It is
caused by a number of
hyaline(non-dematiaceous)
hyphomycetes where the
tissue morphology of the
causitive organism is
mycelial.
19. CLASS COELOMYCETES
• Coelomycetes are asexual Dikarya that produce their conidia
inside some kind of enclosing structure.
• The fungal hyphae germinate from conidia and form an
aggregated mass until they form a fertile layer of densely
packed conidiophores.
• Conidiophores are simple or branched hyphae that develop
specialized cells (conidiogenous) from which asexual conidia
are produced. It is this mass of hyphae that create the
fruiting structure known as a conidiomata.
20. • If this structure completely surrounds the conidia it is called
a pycnidium; if the conidia are borne in a more open
structure with a wall only around the lower part it is an
acervulus.
• The pycnidium is very light coloured where it is sunken in the
host tissues but dark on top.
• This is a common phenomenon among pycnidial fungi.
• Most pycnidia release their spores in a wet mass that is
extruded out through the apical pore (ostiole). These often
collect in large amounts and are either transported away by
insects or will flow along with rain water.
21. • Pycnidia resemble the fruiting structures of ascomycetes
called ascomata
• The second main type of conidomata are acervuli.
• Like pycnidia, acervuli also produce a mat of closely packed
conidiophores but instead grow in a raised mass.
• Unlike pycnidia, acervuli are typically open and cup-shaped
and the opening by which conidia are released is much larger
than that of a pycnidium.
22.
23. • More commonly these fungi grow on living and dead plants.
• Some pycnidia and acervuli can be highly complex and be
composed of several cavities.
• Orders:
• Melanconiales (producing spores in acervuli)
• Sphaeropsidales (producing spores in pycnidia)
• Pycnothyriales (produces pycnothyrial conidiomata.)
26. CLASS BLASTOMYCETES
• Members of this form-class are characterized by yeast-like
cells which propagate by budding.
• A pseudomycelium may or may not be formed.
• True mycelium is either lacking or is not well developed.
• Most of the members are saprobes occuring on
flowers,wood, leaves, and barks.
• Some of them occur on fresh and sea water.
• Some associated with the plant disease like powdery
mildews, rusts and smuts.
27. • Anamorphic yeasts can be
recovered from most
ecological niches—animals,
plants and their surfaces,
fresh and marine water,
soils, and environments such
as manufacturing plants,
tanning fluids, and mineral
oils.
28. • They comprises anamorphic (asexual or imperfect) yeast
fungi that lack fruit bodies (conidiomata), have no
dikaryophase, and are usually unicellular rather than
filamentous.
• The thallus consists of individual cells.
• Approximately 80 genera comprising about 600 species are
recognized.
• Blastomycetes are of great economic importance in two
respects: the production of products and the spoilage of raw
materials and products.
29. • Blastomycetes are also recognized pathogens in medicine.
• Both Candida, causing candidiasis or candidosis, and
Cryptococcus, causing cryptococcosis, are opportunistic
pathogens that cause systemic infections only in individuals
with lowered resistance.
• Blastomyces dermatitidis is the causal agent of
blastomycosis, an invasive and often serious fungal infection
found occasionally in humans and other animals in regions
where the fungus is endemic.
• The causal organism is a fungus living in soil and wet,
decaying wood, often in an area close to a waterway such as
a lake, river or stream.
30. • Blastomycosis is generally
readily treatable with
systemic antifungal drugs
once it is correctly
diagnosed; however,
delayed diagnosis is very
common except in highly
endemic areas.
31.
32. BIBILIOGRAPHY
AN INTRODUCTION TO MYCOLOGY:
• Alexopoulos, Mims,Blackwell
AN INTRODUCTION TO MYCOLOGY
• R.S Mehrotra,KR Aneja
• Classes of deuteromycotina-website.nbm-mnb.ca › Home › Diversity
and classification
