Biol 106 L Kingdorm Fungi
Kingdom: Fungi
Characteristics of Fungi
• The fungi live by absorptive nutrition, secreting
digestive enzymes that break down large food molecules
and absorbing the breakdown products.
• Some are saprobes (feeding on dead matter); others are
parasites.
• A few have mutually beneficial (symbiotic) relationships
with other organisms. Mycorrhizae are mutualistic
associations of fungi and plant roots. The fungus obtains
organic compounds, while the plant is provided with water
and soil minerals.
• Lichens are symbiotic associations of a fungus with a
cyanobacterium, a unicellular photosynthetic eukaryote
(algae), or both.
Characteristics of Fungi
• The production of chitin is a shared derived trait for
fungi, choanoflagellates, and animals. Chitin is a
complex polysaccharide found in the exoskeletons
of arthropods (insects) and some Protists. The
presence of chitin in fungi is evidence that all fungi are
more closely related to animals than to plants.
• The kingdom Fungi consists of four phyla:
Chytridiomycota, Zygomycota, Ascomycota, and
Basidiomycota.
• The four phyla are primarily distinguished by their
methods and structures of reproduction. If fungi are
determined to reproduce only asexually the placed in a
group temporarily called the Deuteromycota. This is
not a phylum but a temporary “holding area” and when
they are linked by biochemical similarities to one of the
4 major phylum, they are added to the phylum to which
they are most similar.
Characteristics of Fungi
Characteristics of Fungi
• Unicellular forms are
found in all of the
fungal phyla.Those of
the Zygomycota,
Ascomycota, and
Basidiomycota are
called yeasts. Yeasts
may reproduce by
budding, fission, or
sexual means.
Characteristics of Fungi
• The vegetative body of a multicellular fungus is called
the mycelium (plural mycelia). This compose the
majority of the fungi and can cover large areas!
• The mycelium is composed of threadlike filaments of
cells called hyphae (singular hypha).
• Within the hyphae of two clades, cell-like compartments
are formed by incomplete cross-walls called septa
(singular septum). Fungi which have the cross-walls are
called Septate fungi.
• Pores in septa allow free movement of organelles,
sometimes even nuclei, and other materials.
• Some hyphae with out the septa and are like a
continous tube of chitin. They are described as
coenocytic—they have no internal separations (septa) ,
therefore no compartments. Fungi which are coenocytic
are called Aseptate fungi.
Characteristics of Fungi
Aseptate vs. Septate
Characteristics of Fungi
• The hyphae may be widely dispersed to forage for
nutrients or they may be clumped together in a cottony
mass to exploit a rich nutrient source.
• Sometimes the mycelium becomes reorganized into a
fruiting (reproductive) structure, such as a
mushroom.
• Rhizoids are modified hyphae, which anchor
Chytridiomycota to a substrate. These rhizoids are not
homologous to the rhizoids of plants because they are
not specialized to absorb water and nutrients. Throughout
the mycelium (except in fruiting structures), all the hyphae
are very close to their environmental food source.
• Fungi are tolerant to highly hypertonic environments.
(Can grow on materials which have a high sugar
concentration, when bacteria can not.)
• Many can tolerate temperatures as low as 5–6C below
freezing. Some can tolerate temperatures as high as 50
C or more.
Characteristics of Fungi
• The majority of fungi are saprobes, living on dead
organisms.
• Saprobic fungi (along with bacteria) are Earth’s primary
decomposers.
• Fungi are the principal decomposers of cellulose and
lignin.
• Facultative parasites can attack living organisms but
they can also be grown on defined media.
• Obligate parasites grow only on their specific host.
• Most predatory fungi secrete sticky substances from the
hyphae. Trapped prey are penetrated by hyphae and
eventually killed.
• Some predatory species form a ring with modified
hyphae that constricts around nematodes (small round
worms). The crawling nematode triggers these rings to
swell and trap the worm. Hyphae quickly invade and
digest the worm.
Parasitic and Predatory Fungi
Impact of Fungal Parasites
• Fungal pathogens are a major cause of death among
people with compromised immune systems.
• Most patients with AIDS die of fungal diseases such as
Pneumocystis carinii.
• Candida albicans and other yeasts also cause severe
diseases in those with AIDS.
• Other less severe and common diseases include
ringworm and athlete’s foot.
• Plant diseases include black stem rust, smuts, blights,
mildews, and others. Many are responsible for extensive
crop and forest damage. The American Chestnut blight
is due to a fungal parasite that was introduced
accidentally to the U.S. from China. This parasitic fungi
is responsible for the loss of thousands of chestnut trees
on the eastern coast of the U.S.
Fungal Asexual Reproduction
• Asexual reproduction among the fungi
includes:
– The production of haploid spores within
sporangia.
– The production of naked spores at the tips of
hyphae (not within sporangia) called conidia.
– Cell division by unicellular fungi—either equal
division (fission) or production of a daughter
cell (budding).
– Simple breakage of the mycelium.
Fungal Sexual Reproduction
• Such fungi have some unusual sexual
reproduction features:
– There are no gamete cells, just gamete
nuclei.
– The hyphae are neither diploid (2n) or haploid
(n), but dikaryotic (n + n). Each hyphae
carries copies of each nucleus of the donor
parental cells.
Fungal Sexual Reproduction
• Sexual reproduction involves fusion between different
mating types.
• Some fungi have more than two mating types.
• Mating types cannot be distinguished morphologically.
• Mating can occur only between different mating types,
which prevents self-fertilization.
• Fungi reproduce sexually when hyphae (or motile cells in
chytrids) of different mating types meet and fuse.
• In many fungi, the zygote nuclei are the only diploid
nuclei of the life cycle.
• These nuclei undergo meiosis, producing haploid nuclei.
• Haploid spores divide mitotically to form haploid hyphae.
• This type of life cycle is called a haplontic life cycle and
is a characteristic of many protists.
Phylum: Chytridiomycota (Water molds)
•
•
•
•
•
•
The chytrids (phylum
Chytridiomycota) are the
earliest diverging fungal
lineage.
They are aquatic
microorganisms, formerly
classed with protists but now
classed with fungi because of
the chitin in their cell walls.
They are the only fungi that
have flagella at any stage of the
life cycle.
Chytrids are parasitic or
saprobic, but some are found in
the rumen of ruminants. Most
live in fresh water or moist soil;
some are marine.
Some are unicellular; others
have coenocytic hyphae.
They reproduce both sexually
and asexually.
Phylum: Zygomycota (Terrestrial Molds)
•
•
•
•
•
Zygomycetes (phylum
Zygomycota) have
coenocytic hyphae; they have
only one diploid cell, the
zygote.
Most form occasional stalked
reproductive structures called
sporangiophores.
Sporangiophores may have
one or many sporangia.
One group are the fungal
species in the most common
mycorrhizal associations.
Black bread mold is Rhizopus
stolonifer.
Phylum: Ascomycetes (Sac fungi)
•
•
•
The ascomycetes (phylum Ascomycota) are a large and diverse
group with septate hyphae, and distinguished by the production of asci
(singular ascus).
The ascus contains the products of meiosis.
There are two groups of ascomycetes:
– Those with an ascocarp are called euascomycetes (“true ascomycetes”).
Euascomycetes reproduce asexually by means of conidia that form at the
tips of specialized hyphae. Sexual reproduction of euascomycetes includes
formation of a dikaryon.
- Those without are called hemiascomycetes (“half ascomycetes”).
Most hemiascomycetes are microscopic and some are unicellular.
Baker’s or brewer’s yeast (Saccharomyces cerevisiae) is an
ascomycete. Hemiascomycete yeasts reproduce asexually by budding
or fission.
Penicillium is a genus of green molds. Some species produce the
antibiotic penicillin.
P. roquefortii and P. camembertii provide the flavors to the cheeses
Roquefort and Camembert. Aspergillus tamarii is used to ferment
soybeans to make soy sauce. A. oryzae is used in brewing the
Japanese alcoholic beverage sake.
Phylum: Ascomycota
Phylum: Basidiomycota (Club Fungi)
•
•
•
•
•
•
•
•
•
•
•
About 25,000 species of basidiomycetes (phylum Basidiomycota)
have been described.
They produce a wide variety of fruiting structures (basidiocarps):
puffballs, mushrooms, and giant bracket fungi.
There are more than 3,250 species of mushrooms.
Agaricus bisporus is the common edible one; some Amanita
mushrooms are deadly poisonous.
Bracket fungi are tree parasites.
Smut fungi parasitize cereal grains.
Basidiomycetes have septate hyphae. Basidia, swollen cells at the
tips of hyphae, are the sexual reproductive structures.
Meiosis gives rise to four haploid nuclei, incorporated into
basidiospores on the outside of the basidium.
Basidiospores give rise to haploid hyphae. Hyphae of different
mating types meet and fuse, forming dikaryotic hyphae.This stage
may persist for years, decades, or even centuries.
Eventually, the dikaryotic mycelium produces a fruiting body called a
basidiocarp. These are what you typically recognize as or call a
mushroom.
Some basidiocarps are topped with a cap called a pileus.
Phylum: Basidiomycota
Lichens
•
•
•
•
•
•
•
•
Lichens are a meshwork of two different
organisms. One is a fungus, and the other is
a photosynthetic organism.
Lichens can survive harsh environments.
In spite of this hardiness, lichens are sensitive
to air pollution because they cannot excrete
toxic substances. Hence they are good
biological indicators of air pollution.
The fungi of most lichens are ascomycetes.
The photosynthetic component may be either
a cyanobacterium or a unicellular green alga.
The fungal components cannot grow
independently of their photosynthetic
partners.
Lichen growth forms include crustose,
foliose, and fruticose.
Lichens reproduce simply by fragmentation of
the vegetative body called the thallus.
They can also reproduce by means of
specialized structures called soredia
(singular soredium).
Characteristics of Fungi
• The fungi live by absorptive nutrition, secreting
digestive enzymes that break down large food molecules
and absorbing the breakdown products.
• Some are saprobes (feeding on dead matter); others are
parasites.
• A few have mutually beneficial (symbiotic) relationships
with other organisms. Mycorrhizae are mutualistic
associations of fungi and plant roots. The fungus obtains
organic compounds, while the plant is provided with water
and soil minerals.
• Lichens are symbiotic associations of a fungus with a
cyanobacterium, a unicellular photosynthetic eukaryote
(algae), or both.
Characteristics of Fungi
• The production of chitin is a shared derived trait for
fungi, choanoflagellates, and animals. Chitin is a
complex polysaccharide found in the exoskeletons
of arthropods (insects) and some Protists. The
presence of chitin in fungi is evidence that all fungi are
more closely related to animals than to plants.
• The kingdom Fungi consists of four phyla:
Chytridiomycota, Zygomycota, Ascomycota, and
Basidiomycota.
• The four phyla are primarily distinguished by their
methods and structures of reproduction. If fungi are
determined to reproduce only asexually the placed in a
group temporarily called the Deuteromycota. This is
not a phylum but a temporary “holding area” and when
they are linked by biochemical similarities to one of the
4 major phylum, they are added to the phylum to which
they are most similar.
Characteristics of Fungi
Characteristics of Fungi
• Unicellular forms are
found in all of the
fungal phyla.Those of
the Zygomycota,
Ascomycota, and
Basidiomycota are
called yeasts. Yeasts
may reproduce by
budding, fission, or
sexual means.
Characteristics of Fungi
• The vegetative body of a multicellular fungus is called
the mycelium (plural mycelia). This compose the
majority of the fungi and can cover large areas!
• The mycelium is composed of threadlike filaments of
cells called hyphae (singular hypha).
• Within the hyphae of two clades, cell-like compartments
are formed by incomplete cross-walls called septa
(singular septum). Fungi which have the cross-walls are
called Septate fungi.
• Pores in septa allow free movement of organelles,
sometimes even nuclei, and other materials.
• Some hyphae with out the septa and are like a
continous tube of chitin. They are described as
coenocytic—they have no internal separations (septa) ,
therefore no compartments. Fungi which are coenocytic
are called Aseptate fungi.
Characteristics of Fungi
Aseptate vs. Septate
Characteristics of Fungi
• The hyphae may be widely dispersed to forage for
nutrients or they may be clumped together in a cottony
mass to exploit a rich nutrient source.
• Sometimes the mycelium becomes reorganized into a
fruiting (reproductive) structure, such as a
mushroom.
• Rhizoids are modified hyphae, which anchor
Chytridiomycota to a substrate. These rhizoids are not
homologous to the rhizoids of plants because they are
not specialized to absorb water and nutrients. Throughout
the mycelium (except in fruiting structures), all the hyphae
are very close to their environmental food source.
• Fungi are tolerant to highly hypertonic environments.
(Can grow on materials which have a high sugar
concentration, when bacteria can not.)
• Many can tolerate temperatures as low as 5–6C below
freezing. Some can tolerate temperatures as high as 50
C or more.
Characteristics of Fungi
• The majority of fungi are saprobes, living on dead
organisms.
• Saprobic fungi (along with bacteria) are Earth’s primary
decomposers.
• Fungi are the principal decomposers of cellulose and
lignin.
• Facultative parasites can attack living organisms but
they can also be grown on defined media.
• Obligate parasites grow only on their specific host.
• Most predatory fungi secrete sticky substances from the
hyphae. Trapped prey are penetrated by hyphae and
eventually killed.
• Some predatory species form a ring with modified
hyphae that constricts around nematodes (small round
worms). The crawling nematode triggers these rings to
swell and trap the worm. Hyphae quickly invade and
digest the worm.
Parasitic and Predatory Fungi
Impact of Fungal Parasites
• Fungal pathogens are a major cause of death among
people with compromised immune systems.
• Most patients with AIDS die of fungal diseases such as
Pneumocystis carinii.
• Candida albicans and other yeasts also cause severe
diseases in those with AIDS.
• Other less severe and common diseases include
ringworm and athlete’s foot.
• Plant diseases include black stem rust, smuts, blights,
mildews, and others. Many are responsible for extensive
crop and forest damage. The American Chestnut blight
is due to a fungal parasite that was introduced
accidentally to the U.S. from China. This parasitic fungi
is responsible for the loss of thousands of chestnut trees
on the eastern coast of the U.S.
Fungal Asexual Reproduction
• Asexual reproduction among the fungi
includes:
– The production of haploid spores within
sporangia.
– The production of naked spores at the tips of
hyphae (not within sporangia) called conidia.
– Cell division by unicellular fungi—either equal
division (fission) or production of a daughter
cell (budding).
– Simple breakage of the mycelium.
Fungal Sexual Reproduction
• Such fungi have some unusual sexual
reproduction features:
– There are no gamete cells, just gamete
nuclei.
– The hyphae are neither diploid (2n) or haploid
(n), but dikaryotic (n + n). Each hyphae
carries copies of each nucleus of the donor
parental cells.
Fungal Sexual Reproduction
• Sexual reproduction involves fusion between different
mating types.
• Some fungi have more than two mating types.
• Mating types cannot be distinguished morphologically.
• Mating can occur only between different mating types,
which prevents self-fertilization.
• Fungi reproduce sexually when hyphae (or motile cells in
chytrids) of different mating types meet and fuse.
• In many fungi, the zygote nuclei are the only diploid
nuclei of the life cycle.
• These nuclei undergo meiosis, producing haploid nuclei.
• Haploid spores divide mitotically to form haploid hyphae.
• This type of life cycle is called a haplontic life cycle and
is a characteristic of many protists.
Phylum: Chytridiomycota (Water molds)
•
•
•
•
•
•
The chytrids (phylum
Chytridiomycota) are the
earliest diverging fungal
lineage.
They are aquatic
microorganisms, formerly
classed with protists but now
classed with fungi because of
the chitin in their cell walls.
They are the only fungi that
have flagella at any stage of the
life cycle.
Chytrids are parasitic or
saprobic, but some are found in
the rumen of ruminants. Most
live in fresh water or moist soil;
some are marine.
Some are unicellular; others
have coenocytic hyphae.
They reproduce both sexually
and asexually.
Phylum: Zygomycota (Terrestrial Molds)
•
•
•
•
•
Zygomycetes (phylum
Zygomycota) have
coenocytic hyphae; they have
only one diploid cell, the
zygote.
Most form occasional stalked
reproductive structures called
sporangiophores.
Sporangiophores may have
one or many sporangia.
One group are the fungal
species in the most common
mycorrhizal associations.
Black bread mold is Rhizopus
stolonifer.
Phylum: Ascomycetes (Sac fungi)
•
•
•
The ascomycetes (phylum Ascomycota) are a large and diverse
group with septate hyphae, and distinguished by the production of asci
(singular ascus).
The ascus contains the products of meiosis.
There are two groups of ascomycetes:
– Those with an ascocarp are called euascomycetes (“true ascomycetes”).
Euascomycetes reproduce asexually by means of conidia that form at the
tips of specialized hyphae. Sexual reproduction of euascomycetes includes
formation of a dikaryon.
- Those without are called hemiascomycetes (“half ascomycetes”).
Most hemiascomycetes are microscopic and some are unicellular.
Baker’s or brewer’s yeast (Saccharomyces cerevisiae) is an
ascomycete. Hemiascomycete yeasts reproduce asexually by budding
or fission.
Penicillium is a genus of green molds. Some species produce the
antibiotic penicillin.
P. roquefortii and P. camembertii provide the flavors to the cheeses
Roquefort and Camembert. Aspergillus tamarii is used to ferment
soybeans to make soy sauce. A. oryzae is used in brewing the
Japanese alcoholic beverage sake.
Phylum: Ascomycota
Phylum: Basidiomycota (Club Fungi)
•
•
•
•
•
•
•
•
•
•
•
About 25,000 species of basidiomycetes (phylum Basidiomycota)
have been described.
They produce a wide variety of fruiting structures (basidiocarps):
puffballs, mushrooms, and giant bracket fungi.
There are more than 3,250 species of mushrooms.
Agaricus bisporus is the common edible one; some Amanita
mushrooms are deadly poisonous.
Bracket fungi are tree parasites.
Smut fungi parasitize cereal grains.
Basidiomycetes have septate hyphae. Basidia, swollen cells at the
tips of hyphae, are the sexual reproductive structures.
Meiosis gives rise to four haploid nuclei, incorporated into
basidiospores on the outside of the basidium.
Basidiospores give rise to haploid hyphae. Hyphae of different
mating types meet and fuse, forming dikaryotic hyphae.This stage
may persist for years, decades, or even centuries.
Eventually, the dikaryotic mycelium produces a fruiting body called a
basidiocarp. These are what you typically recognize as or call a
mushroom.
Some basidiocarps are topped with a cap called a pileus.
Phylum: Basidiomycota
Lichens
•
•
•
•
•
•
•
•
Lichens are a meshwork of two different
organisms. One is a fungus, and the other is
a photosynthetic organism.
Lichens can survive harsh environments.
In spite of this hardiness, lichens are sensitive
to air pollution because they cannot excrete
toxic substances. Hence they are good
biological indicators of air pollution.
The fungi of most lichens are ascomycetes.
The photosynthetic component may be either
a cyanobacterium or a unicellular green alga.
The fungal components cannot grow
independently of their photosynthetic
partners.
Lichen growth forms include crustose,
foliose, and fruticose.
Lichens reproduce simply by fragmentation of
the vegetative body called the thallus.
They can also reproduce by means of
specialized structures called soredia
(singular soredium).