Transcript Fungi (ch 31) Campbell PPT

What is the biggest organism
in this Oregonian forest?
Hint, it is pictured
The honey mushroom fungus
Fun-gi vids
FUNGI REPRODUCTION
• growing mold time-lapse
BAD FUNGI
• parasitic fungi time-lapse
GOOD FUNGI
• pig decomposition time-lapse
LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 31
Fungi
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Key ideas
• Unique life cycle
• Role as a symbiont, parasitically,
commensalistically, and mutualistically
• Role as a pioneer species
• Role as a decomposer
Concept 31.1: Fungi are heterotrophs that
feed by absorption
• Fungi are heterotrophs and absorb nutrients from
outside of their body
• Fungi use enzymes to break down a large variety
of complex molecules into smaller organic
compounds
• Fungi exhibit diverse lifestyles
– Decomposers
–
rabbit decomposing
– Parasites
–
previously shown, with new bonus mushroom and slime mold time-lapse
– Mutualists
© 2011 Pearson Education, Inc.
Animation: Fungal Reproduction and Nutrition
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Anatomy basics
• Fungi consist of mycelia, networks of
branched hyphae adapted for absorption
• A mycelium’s structure maximizes its surface
area-to-volume ratio
• Fungal cell walls contain chitin
© 2011 Pearson Education, Inc.
Figure 31.2
Reproductive structure
Hyphae
Spore-producing
structures
60 m
Mycelium
TWO FORMS OF HYPHAE
Nuclei
Cell wall
Cell wall
Pore
Septum
(a) Septate hypha
Nuclei
(b) Coenocytic hypha
How much hyphae did she eat?
1 pinch of soil can contain 1 km of hyphae
Nematode
Some
unique
fungi have
specialized
hyphae
called
haustoria
that allow
them to
penetrate
the tissues
of their host
Hyphae
25 m
(a) Hyphae adapted for trapping and killing prey
Fungal hypha
Plant
cell
wall
Plant cell
Haustorium
(b) Haustoria
Plant cell
plasma
membrane
• Mycorrhizae are mutually beneficial
relationships between fungi and plant roots,
which most vascular plants have
– Ectomycorrhizal fungi form sheaths of hyphae over
a root and also grow into the extracellular spaces of
the root cortex
– Arbuscular mycorrhizal fungi extend hyphae
through the cell walls of root cells and into tubes
formed by invagination of the root cell membrane
• Which is pictured  ?
• Which is pictured on the previous slide?
© 2011 Pearson Education, Inc.
Concept 31.2: Fungi produce spores
through sexual or asexual life cycles
• Fungi propagate themselves by producing vast
numbers of spores, either sexually or asexually, or
both
© 2011 Pearson Education, Inc.
Fungi life cycle paths can be funky
Key
Haploid (n)
Heterokaryotic
Diploid (2n)
Spore-producing
structures
Spores
Mycelium
ASEXUAL
REPRODUCTION
GERMINATION
Fungi life cycle paths can be funky
Key
Haploid (n)
PLASMOGAMY
Heterokaryotic
Heterokaryotic
stage
Diploid (2n)
Spore-producing
structures
Spores
Mycelium
ASEXUAL
REPRODUCTION
GERMINATION
KARYOGAMY
SEXUAL
REPRODUCTION
Zygote
Fungi life cycle paths can be funky
Key
Haploid (n)
PLASMOGAMY,
Heterokaryotic
based on pheromone compatibility
Heterokaryotic
stage
Diploid (2n)
Spore-producing
structures
KARYOGAMY
Spores
Mycelium
ASEXUAL
REPRODUCTION
GERMINATION
SEXUAL
REPRODUCTION
Zygote
GERMINATION
MEIOSIS
Spores
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Asexual Reproduction
• In addition to sexual reproduction, many fungi
can reproduce asexually
• Molds produce haploid spores by mitosis and
form visible mycelia
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Figure 31.7
CHECK-IN Q
• Yeast are unicellular and reproduce by
budding. Then what makes them fungi?
10 m
Parent
cell
Bud
Concept 31.3: The ancestor of fungi was an
aquatic, single-celled, flagellated protist
• DNA evidence suggests that
– Fungi are most closely related to unicellular
nucleariids
– Animals are most closely related to unicellular
choanoflagellates
• Based on this, did fungi and animals split before or after
the emergence of multicellularity?
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The Move to Land
• If fungi are heterotrophic, how does it make
sense that they were among the first land
colonizers?
© 2011 Pearson Education, Inc.
The Move to Land
• If fungi are eukaryotic, how does it make sense
that they were among the first land colonizers?
© 2011 Pearson Education, Inc.
Concept 31.4: Fungi have radiated into a
diverse set of lineages
• Molecular analyses have helped clarify
evolutionary relationships among fungal groups,
although areas of uncertainty remain
© 2011 Pearson Education, Inc.
Figure 31.11
Hyphae
25 m
Fungal hypha
25 m
Chytrids (1,000 species)
Zygomycetes (1,000 species)
Glomeromycetes (160 species)
Ascomycetes (65,000 species)
Basidiomycetes (30,000 species)
Chytrids
• Chytrids (phylum Chytridiomycota) are found in
freshwater and terrestrial habitats
• They can be decomposers, parasites, or
mutualists
– Chytrids are unique among fungi in having flagellated
spores, called zoospores
© 2011 Pearson Education, Inc.
Video: Allomyces Zoospore Release
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Video: Phlyctochytrium Zoospore Release
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Zygomycetes
• The zygomycetes (phylum Zygomycota) include
fast-growing molds, parasites
– The life cycle of black bread mold (Rhizopus stolonifer) is fairly
typical of the phylum
– Its hyphae are coenocytic
– Asexual sporangia produce haploid spores
© 2011 Pearson Education, Inc.
Figure 31.UN02
Chytrids
Zygomycetes
Glomeromycetes
Ascomycetes
Basidiomycetes
ZYGOMYCETES LIFE CYCLE
PLASMOGAMY
Mating
type ()
Mating
type ()
Gametangia with
haploid nuclei
100 m
Rhizopus
growing
on bread
Young
zygosporangium
(heterokaryotic)
SEXUAL
REPRODUCTION
Dispersal and
germination
Zygosporangium
KARYOGAMY
Flagellum
Sporangia
Sporangium
ASEXUAL
REPRODUCTION
Diploid
nuclei
MEIOSIS
Key
Dispersal and
germination
50 m
Mycelium
Haploid (n)
Heterokaryotic (n  n)
Diploid (2n)
Figure 31.14
0.5 mm
Pilobolus aiming its sporangia toward light as that is
where edible vegitation would be growing (grass).
Grass is eaten, spores spread in feces.
Glomeromycetes
• The glomeromycetes (phylum Glomeromycota)
were once considered zygomycetes
• They are now classified in a separate clade
• Glomeromycetes form arbuscular mycorrhizae
© 2011 Pearson Education, Inc.
Figure 31.UN03
Chytrids
Zygomycetes
Glomeromycetes
Ascomycetes
Basidiomycetes
Arbuscular mycorrhizae
2.5 m
Ascomycetes
• Ascomycetes (phylum Ascomycota) produce
sexual spores in saclike asci contained in fruiting
bodies called ascocarps
– Ascomycetes are commonly called sac fungi
– Ascomycetes vary in size and complexity from
unicellular yeasts to elaborate cup fungi and morels
© 2011 Pearson Education, Inc.
Figure 31.UN04
Chytrids
Zygomycetes
Glomeromycetes
Ascomycetes
Basidiomycetes
Figure 31.16
Morchella esculenta,
the tasty morel
Tuber melanosporum, a truffle
Figure 31.17
Conidia;
mating type ()
Key
Dispersal
Germination
Haploid (n)
Dikaryotic (n  n)
Diploid (2n)
Mating
type ()
ASEXUAL
REPRODUCTION Hypha
PLASMOGAMY
Ascus
(dikaryotic)
Conidiophore
Mycelia
Dikaryotic
hyphae
Mycelium
Germination
Dispersal
Asci
Ascocarp
SEXUAL
REPRODUCTION
Eight
ascospores
KARYOGAMY
Diploid nucleus
(zygote)
Four
haploid
nuclei
MEIOSIS
Basidiomycetes
• Basidomycetes (phylum Basidiomycota) include
mushrooms, puffballs, and shelf fungi,
mycorrhizae, and plant parasites
– The phylum is defined by a clublike structure called a
basidium, a transient diploid stage in the life cycle
– The basidiomycetes are also called club fungi
– Many basidiomycetes are decomposers of wood
© 2011 Pearson Education, Inc.
Figure 31.UN05
Chytrids
Zygomycetes
Glomeromycetes
Ascomycetes
Basidiomycetes
Figure 31.18
Shelf fungi
Puffballs emitting
spores
Maiden veil fungus
(Dictyphora)
Figure 31.19
Key
Dikaryotic
mycelium
PLASMOGAMY
Haploid (n)
Dikaryotic (n  n)
Diploid (2n)
Mating
type ()
Mating
type ()
Haploid
mycelia
SEXUAL
REPRODUCTION
Gills lined
with basidia
Dispersal
and
germination
Basidiospores
(n)
Basidium with
four basidiospores
Basidium
Basidia
(n  n)
Basidium containing
four haploid nuclei
KARYOGAMY
MEIOSIS
1 m
Basidiospore
Diploid
nuclei
Basidiocarp
(n  n)
Figure 31.20
• Basidiomycetes can produce mushrooms
quickly
• Some species may produce “fairy rings”
Imagine a fungi-free world…
Concept 31.5: Fungi play key roles in
nutrient cycling, ecological interactions,
and human welfare
• Fungi interact with other organisms as
decomposers, mutualists, and pathogens
© 2011 Pearson Education, Inc.
Fungi as Decomposers/Nutrient recylers
• Fungi are efficient decomposers of organic
material including cellulose and lignin
• Fungi are also used in bioremediation projects
© 2011 Pearson Education, Inc.
Fungi as Mutualists
© 2011 Pearson Education, Inc.
Fungus-Plant Mutualisms
• Mycorrhizae are enormously important in natural
ecosystems and agriculture
– Plants harbor harmless symbiotic endophytes, fungi
that live inside leaves or other plant parts
– Endophytes make toxins that deter herbivores and
defend against pathogens
© 2011 Pearson Education, Inc.
Figure 31.21
RESULTS
Leaf area damaged (%)
Leaf mortality (%)
Endophyte not present; pathogen present (EP)
Both endophyte and pathogen present (EP)
30
20
10
0
EP
EP
15
10
5
0
EP
EP
Fungianimal
symbiosis
Lichens
• A lichen is a symbiotic association between a
photosynthetic microorganism and a fungus
– The photosynthetic component is green algae or
cyanobacteria
– The fungal component is most often an ascomycete
• The symbioses are so complete that lichens are
given scientific names
© 2011 Pearson Education, Inc.
Figure 31.23
A foliose
(leaflike) lichen
Crustose
(encrusting) lichens
A fruticose (shrublike) lichen
Lichen anatomy
Ascocarp of fungus
50 m
Fungal
hyphae Algal
layer
Fungal hyphae
Algal cell
Soredia
• Lichens are important pioneers on new rock and
soil surfaces
• Lichens may have helped the colonization of
land by plants 550–600 million years ago
© 2011 Pearson Education, Inc.
Fungi as Pathogens
• About 30% of known fungal species are parasites
or pathogens, mostly on or in plants
• Each year, 10% to 50% of the world’s fruit harvest
is lost due to fungi
• Some fungi that attack food crops are toxic to
humans
© 2011 Pearson Education, Inc.
Figure 31.25
(b) Tar spot
fungus
on maple
leaves
(a) Corn smut on corn
(c) Ergots on rye
Fungi caused Salem Witch Trials?
• Ergotism is characterized by gangrene, nervous
spasms, burning sensations, hallucinations, and
temporary insanity
– Ergots contain lysergic acid, the raw material for LSD
© 2011 Pearson Education, Inc.
Global amphibian populations are down due to fungal infection (mycosis)
California
Sixty
Lake
Basin
N
Yellow-legged frogs
killed by B. dendrobatidis
infection
Key
Boundary of chytrid spread
Lake status in 2009:
2007
Frog population extinct
Treatment lake: frogs
treated with fungicides
and released
Practical Uses of Fungi
• Humans eat many fungi and use others to
make cheeses, alcoholic beverages, and
bread
• Some fungi are used to produce antibiotics
for the treatment of bacterial infections
– For example, the ascomycete Penicillium
© 2011 Pearson Education, Inc.
Fungal production of antibiotic
Staphylococcus
Penicillium
Zone of
inhibited
growth
Figure 31.UN06
Fungal
Phylum
Distinguishing Features of
Morphology and Life Cycles
Chytridiomycota
(chytrids)
Flagellated spores
Zygomycota
(zygote fungi)
Resistant zygosporangium
as sexual stage
Glomeromycota
(arbuscular
mycorrhizal
fungi)
Arbuscular mycorrhizae
formed with plants
Ascomycota
(ascomycetes, or
sac fungi)
Sexual spores (ascospores)
borne internally in sacs
called asci; vast numbers
of asexual spores (conidia)
produced
Basidiomycota
(basidiomycetes,
or club fungi)
Elaborate fruiting body
(basidiocarp) containing
many basidia that
produce sexual spores
(basidiospores)
Figure 31.UN08
Figure 31.UN09
Figure 31.UN10