Kingdom Fungi
Chapter 21
LEARNING OBJECTIVE 1
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Describe the distinguishing
characteristics of the kingdom Fungi
Fungi
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Eukaryotes that lack chlorophyll and are
heterotrophic
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Absorb predigested food through the cell
wall and plasma membrane
WAYS FUNGI AFFECTS LIVING
THINGS
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Cause food spoilage
Make food products better
Provides a food source
Provide medicine
Cause plant disease
Damage property
Cause disease
Examples of foods made
possible by fungi
Yeast
• Beer and Wine
• Bread
Mushrooms
• White button,
crimini,portabella
• Truffles, chanterelles
Mycoprotein
(food additive like tofu)
Cheese
•Rennin,
•blue cheese
Soy sauce
Tempeh
Citric acid
(soft drinks)
Evolutionary History of Fungi
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•
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Fungi appeared around 1.5 billion years
ago.
Earliest fungi were aquatic.
Fungi are more closely related to animals
than plants.
Fungi probably evolved from a flagellated
protist.
KEY TERMS
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CHITIN
•
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A nitrogen-containing polysaccharide that
forms cell walls of many fungi
HYPHA
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One of the threadlike filaments composing the
mycelium of a fungus
KEY TERMS
•
MYCELIUM
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Vegetative (nonreproductive) body of most
fungi, consisting of a branched network of
hyphae
Other fungi (yeasts) are unicellular
Filamentous Fungi
Hyphae
(c)
(d)
(e)
(a) A fungal mycelium (b) Electron micrograph
growing on agar in a of a mycelium.
culture dish. In
nature, fungal
mycelia are rarely
so symmetrical.
(c) A hypha divided into cells by
septa; each cell is monokaryotic.
In some fungi the septa are
perforated (as shown).
(d) A septate hypha in which
each cell is dikaryotic (has
two nuclei).
(e) A coenocytic hypha.
Fig. 21-1, p. 407
LEARNING OBJECTIVE 2
•
Explain the fate of a fungal spore that
lands on an appropriate food source
KEY TERMS
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SPORE
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A reproductive cell that gives rise to individual
offspring in fungi and certain other organisms
Spores
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Fungi reproduce by spores
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May be produced sexually or asexually
When a fungal spore comes into contact
with an appropriate food source, the spore
germinates and begins to grow a
mycelium
Germination: Spore to Mycelium
Spore
Hypha
Mycelium
Fig. 21-2, p. 407
LEARNING OBJECTIVE 3
•
List distinguishing characteristics and
give examples of each of the following
fungal groups: chytridiomycetes,
zygomycetes, glomeromycetes,
ascomycetes, and basidiomycetes
Major Phyla of Fungi
Basidiomycetes
Ascomycetes
Zygomycetes
Chytrids
Glomeromycetes
Evolution of
ascospores
Evolution of
basidiospores
Evolution of
dikaryotic stage
Loss of flagellum
Common
flagellated
ancestor
Fig. 21-3, p. 408
KEY TERMS
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CHYTRID (chytridiomycetes)
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A fungus characterized by production of
flagellated cells at some stage in its life
history
A parasitic chytrid is partly responsible for
declining amphibian populations
A Chytrid
KEY TERMS
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ZYGOMYCETE
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A fungus characterized by production of
nonmotile, asexual spores and sexual
zygospores
Black bread mold is a zygomycete
A Zygomycete
Life Cycle: Black Bread Mold
7 Spores germinate and
produce haploid mycelia.
Spore germinates
1a In asexual reproduction,
ASEXUAL
certain hyphae form
REPRODUCTION
sporangia in which clusters
(by spores)
of black, asexual, haploid
Haploid (n)
spores develop. When
released, they give rise
Sporangia to new hyphae.
Spores
+
-
Sporangium
containing
spores
produced
by mitosis
6 Meiosis occurs
and zygospore
germinates;
hypha develops
sporangium at
its tip.
SEXUAL REPRODUCTION
HAPLOID (n)
STAGE
Germination of
zygospore
DIPLOID (2n)
STAGE
Mature zygospore Gametangia
within zygosporangium
Meiosis
5 Zygospore develops
from zygote; it is
encased by thick-walled,
black zygosporangium.
1b Hyphae of (+)
and (-) mating
types grow
toward one
another.
Karyogamy
+
-
+
-
2 When (+) and (-)
hyphae meet,
they form
Plasmogamy
gametangia.
3 Plasmogamy occurs
as gametangia fuse.
4 Karyogamy occurs with nuclei
fusing to form diploid zygote.
Fig. 21-6, p. 410
Microsporidium Infection
Microsporidian cell
Polar tube
Host cell
1 Spore of
microsporidium
has coiled
polar tube.
2 Spore ejects
its polar tube
and penetrates
host cell.
3 Infective
cytoplasm is
injected into
host cell.
Fig. 21-7, p. 411
Microsporidian cell
Polar tube
Host cell
1. Spore of
microsporidium
has coiled
polar tube.
2. Spore ejects
its polar tube
and penetrates
host cell.
3. Infective
cytoplasm is
injected into
host cell.
Stepped Art
Fig. 21-7, p. 411
Animation: Zygomycete Life
Cycle
CLICK
TO PLAY
KEY TERMS
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GLOMEROMYCETE
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A fungus that forms a distinctive branching
form (arbuscular mycorrhizae) of
endomycorrhizae with roots of most trees and
herbaceous plants
Glomeromycetes
Cells of
root cortex
Root epidermis
Soil
Vesicle
Root hair
Arbuscule
Spore
Cortex
cell
Hyphae of fungus
Fig. 21-8, p. 412
KEY TERMS
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ASCOMYCETE
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A fungus characterized by production of
nonmotile, asexual conidia and sexual
ascospores
Ascomycetes include yeasts, cup fungi,
morels, truffles, pink and green molds
Conidia
Conidia
Fig. 21-9, p. 412
Life Cycle: Ascomycetes
In asexual reproduction,
hyphae produce haploid
conidia.
Conidia
Germinating
conidium
ASEXUAL
9 When
REPRODUCTION
released,
(by spores)
ascospores
Conidiophore
Haploid (n)
germinate and
1 Haploid mycelia
form new
(–)
mating
type
of opposite mating
haploid
types both produce
mycelia.
coenocytic sexual
8 Each nucleus
hyphae.
becomes
(–) mating type
incorporated
Plasmogamy
into an
2 Plasmogamy
ascospore.
Nuclei
occurs as hyphae
migrate.
SEXUAL REPRODUCTION of the two mating
Mature ascus
HAPLOID (n) types fuse and
has eight
STAGE
haploid
nuclei are exchanged.
3 Dikaryotic
ascospores.
DIKARYOTIC
hyphae form
Second meiotic
STAGE
and produce
division
7 Mitosis
(n
+
n)
asci.
produces
First
eight haploid
DIPLOID Developing
meiotic
nuclei.
(2n)
ascus with
division
n + n nuclei
STAGE
6 Meiosis occurs,
Zygote
4 Hyphae form
forming four
Nuclei
an ascocarp.
Meiosis
haploid nuclei.
fuse
Ascocarp
5 Karyogamy occurs in
Karyogamy
each ascus. Two haploid nuclei
fuse, forming a diploid zygote
nucleus.
Mycelium
Fig. 21-10, p. 414
Sexual Reproduction in
Ascomycetes
Penicillium. The mold Penicillium
produces penicillin, which inhibits the
growth of Gram-positive bacteria.
Penicillium
WWI, bacterial
infections killed
more soldiers than
bullets did directly.
1928 Dr. Fleming working
at St. Mary’s Hospital in
London noticed that mold
growing on staph bacterial
culture plates had killed
the pathogen
zone of dead
bacteria
Penicillin kills bacteria by interfering with their
ability to synthesize cell wall.
In this sequence, Escherichia coli were incubated in
penicillin for 30 minutes. The bacteria lengthen, but cannot divide.
Eventually the weak cell wall ruptures (last panel).
Animations
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Mode of action of Pennicillin:
http://www.microbelibrary.org/microbeli
brary/files/ccImages/Articleimages/Spe
ncer/spencer_cellwall.html
Development of Antibiotic resistance:
http://www.sumanasinc.com/scienceinf
ocus/sif_antibiotics.html
KEY TERMS
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BASIDIOMYCETE
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A fungus characterized by production of
sexual basidiospores
Basidiomycetes include mushrooms, puffballs,
rusts, smuts
Basidiomycete Fruiting Bodies
Sexual Reproduction in
Basidiomycetes
Cap
Gill, bearing basidia
Basidiospore
Basidium
Gills
Button
stage
Stalk
Fruiting body
(Basidiocarp)
Base
Mycelium
(a) Compacted hyphae form the basidiocarp
commonly called a mushroom. Numerous
basidia are borne on the gills.
(b) Each basidium produces
four basidiospores, which are
attached to the basidium.
Fig. 21-13, p. 417
Life Cycle: Basidiomycetes
1 Basidiospores germinate
and form primary mycelia.
Basidiospores
released
2 Plasmogamy occurs
with the fusion of two
(n) hyphae of
different mating
types.
Basidiospores
forming
Plasmogamy
HAPLOID (n)
STAGE
Second meiotic
division
First meiotic
division
6 Meoisis occurs,
producing four
haploid nuclei
that become
basidiospores.
Meiosis
DIPLOID
(2n)
STAGE
Zygote nucleus
3 Fast-growing
secondary
mycelium is
DIKARYOTIC
produced,
STAGE
composed of
(n + n)
dikaryotic
(n + n) hyphae.
Karyogamy
5 Basidia form along gills of
basidiocarps. In each
basidium karyogamy
occurs, producing a
zygote nucleus.
Gills
4 Basidiocarps
periodically
develop from
secondary
mycelium.
Basidiocarp
Secondary
mycelium
Fig. 21-14, p. 418
Animation: Club Fungus Life
Cycle
CLICK
TO PLAY
LEARNING OBJECTIVE 4
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Explain the ecological significance of
fungi as decomposers
Decomposers
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Most fungi are decomposers
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Break down organic compounds in dead
organisms, leaves, garbage, and wastes into
simpler materials that can be recycled
Without continuous decomposition
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Essential minerals would be unavailable for
use by new generations of organisms
Life would cease
LEARNING OBJECTIVE 5
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Describe the important ecological role
of mycorrhizae
Mycorrhizae
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Mutualistic relationships between fungi
and roots of plants
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Fungus supplies minerals to plant
Plant secretes organic compounds needed by
fungus
KEY TERMS
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ENDOMYCORRHIZAL FUNGI
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Fungi that form mycorrhizae that extend into
plant roots
ECTOMYCORRHIZAL FUNGI
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Fungi that form mycorrhizae consisting of a
dense sheath over the root’s surface
Experiment: Mycorrhizae
Mycorrhizae
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“myco” = fungus and “rhiza” = root
Symbiotic association between
plant roots and fungi
Several different types of association
(defined by structure of fungus:plant
interface)
Mycorrhizae
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Endomycorrhizae:
Vesicular-Arbuscular Mycorrhizae (VAM, AM).
Most common type of mycorrhizae (textbook: ~240,000 plant species,
~6000 fungal species; Trappe, 1987: ~2/3 of all plant species).
Fungi = Zygomycetes, many kinds of plants (bryophytes, ferns,
gymnosperms, angiosperms) Important step in evolution of land plants?
VAM Fungi haven’t been cultured, can’t degrade complex organic matter,
rely on simple C compounds from plants. Survive as chlamydospores in soil
untilinfection. Plants can usually live without association, but not as well.
Important for P uptake, recently shown to transfer organic N to plant.
Vesicles: survival structures within plant. Fungus can grow along the inside
of the root as root grows.
Arbuscules: highly branched hyphae - transfer nutrients when arbuscules
are digested by plant.
Almost ALL plant species depend on
mycorrhizae to some extent
Types of
mycorrhizae
Plant partners
Vesicular-arbuscular
(VAM)
~150 species of
fungi
Nearly all terrestrial plants
(200,000 species including
grasses, crops, flowering
plants, and flowering trees
not listed below)
Conifer trees, oaks, birches,
beeches, Eucalyptus)
(~2000 species of trees)
Ectomycorrhizae
~5,000-10,000
species of fungi
Effect of mycorrhizal symbiosis (with a
fungus) on pine seedlings
LEARNING OBJECTIVE 6
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Characterize the unique nature of a
lichen
KEY TERMS
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LICHEN
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A compound organism consisting of a
symbiotic fungus and an alga or
cyanobacterium
Lichens have three main growth forms:
crustose, foliose, and fruticose
Lichens
Fruticose lichen (Ramalina)
Surface
layer
(fungal hyphae)
Soredia
Fungal hyphae
interwoven with
photosynthetic
organism
Loosely
woven hyphae
Rock or other surface
to which lichen is attached
(a)This cross section of a typical
lichen shows distinct layers. The
soredium, an asexual reproductive
structure, consists of clusters of
algal or cyanobacterial cells
enclosed by fungal hyphae.
Bottom layer
(fungal hyphae)
Crustose lichens
(Bacidia, Lecanora)
Foliose lichen
(Parmelia)
(b) Lichens vary in color, shape, and overall
appearance. Three growth forms–crustose, foliose,
and fruticose–are shown on a maple branch in
Washington State.
Fig. 21-16, p. 420
Recap of mycorrhizal benefits
• Greater plant
productivity
(larger profits in the timber,
fiber industries)
• Greater reproductive
success for plants
(higher yields for
agriculture)
• Greater ecosystem
stability
Left: No mycorrhizal fungi
Right: With mycorrhizal fungi
Economic Impact
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Foods:
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Food production:
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Mushrooms, morels, truffles
Beer, wine, bread, cheeses, soy sauce
Production of industrial chemicals:
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Citric acid
LEARNING OBJECTIVE 7
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Summarize some of the ways that fungi
impact humans economically
Economic Impact
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Foods:
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Food production:
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Mushrooms, morels, truffles
Beer, wine, bread, cheeses, soy sauce
Production of industrial chemicals:
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Citric acid
Fungal Food Products
Edible Ascomycetes
LEARNING OBJECTIVE 8
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Summarize the importance of fungi to
biology and medicine
Biology and Medicine 1
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Production of medications:
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Penicillin and other antibiotics
Cause important plant diseases:
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Wheat rust, Dutch elm disease, chestnut
blight
Biology and Medicine 2
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Opportunistic pathogens in humans:
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Ringworm, athlete’s foot, candidiasis,
histoplasmosis
Produce mycotoxins:
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Aflatoxins cause liver damage and cancer
The Destroying Angel
Ergot
Ergot
Fig. 21-20, p. 423
Fungal Parasite
Spore
Hypha
Epidermis
Stoma
Air space
Leaf
Haustoria
Fig. 21-21, p. 424
Fungal Plant Pathogens