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Fun-gi vids
• pig decomposition time-lapse• fungus time-lapse• growing mold time-lapse• parasitic fungi time-lapse
LECTURE PRESENTATIONSFor CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
© 2011 Pearson Education, Inc.
Lectures byErin Barley
Kathleen Fitzpatrick
Fungi
Chapter 31
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.
© 2011 Pearson Education, Inc.
Animation: Fungal Reproduction and Nutrition Right-click slide / select “Play”
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.
TWO FORMS OF HYPHAE
(a) Septate hypha (b) Coenocytic hypha
NucleiCell wall
Pore
Septum Nuclei
Cell wall
Some unique fungi have specialized hyphae called haustoria that allow them to penetrate the tissues of their host
(a) Hyphae adapted for trapping and killing prey
(b) Haustoria
Fungal hypha Plantcellwall
Plant cell
Plant cellplasmamembraneHaustorium
NematodeHyphae 25 m
• 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)
Spores
Spore-producingstructures
ASEXUALREPRODUCTION
GERMINATION
Mycelium
PLASMOGAMY
Key
Haploid (n)
Heterokaryotic
Diploid (2n)
Spores
Spore-producingstructures
ASEXUALREPRODUCTION
SEXUALREPRODUCTION
GERMINATION
Zygote
Heterokaryoticstage
KARYOGAMY
Mycelium
Fungi life cycle paths can be funky
PLASMOGAMY, based on pheromone compatibility
Key
Haploid (n)
Heterokaryotic
Diploid (2n)
Spores
Spore-producingstructures
ASEXUALREPRODUCTION
SEXUALREPRODUCTION
GERMINATIONGERMINATION MEIOSIS
Spores
Zygote
Heterokaryoticstage
KARYOGAMY
Mycelium
Fungi life cycle paths can be funky
Asexual Reproduction
• In addition to sexual reproduction, many fungi can reproduce asexually
• Molds produce haploid spores by mitosis and form visible mycelia
© 2011 Pearson Education, Inc.
Figure 31.7
10 m
Parentcell
Bud
CHECK-IN Q•Yeast are unicellular and reproduce by budding. Then what makes them fungi?
• 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?
© 2011 Pearson Education, Inc.
Concept 31.3: The ancestor of fungi was an aquatic, single-celled, flagellated protist
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 31.11Chytrids (1,000 species)
Zygomycetes (1,000 species)
Glomeromycetes (160 species)
Ascomycetes (65,000 species)
Basidiomycetes (30,000 species)
Hyphae 25 m
25 mFungal hypha
Chytrids
• Chytrids (phylum Chytridiomycota) are found in freshwater and terrestrial habitats
• They can be decomposers, parasites, or mutualists
• Molecular evidence supports the hypothesis that chytrids diverged early in fungal evolution
• Chytrids are unique among fungi in having flagellated spores, called zoospores
© 2011 Pearson Education, Inc.
Zygomycetes
• The zygomycetes (phylum Zygomycota) exhibit great diversity of life histories
• They include fast-growing molds, parasites, and commensal symbionts
• 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 31.13
Rhizopusgrowingon bread
Flagellum
Matingtype () Mating
type ()
Gametangia withhaploid nuclei
Youngzygosporangium(heterokaryotic)
PLASMOGAMY
100 m
50 m
ZygosporangiumKARYOGAMY
SEXUALREPRODUCTION
Diploidnuclei
Key
Haploid (n)
Diploid (2n)
Heterokaryotic (n n)
Sporangium
MEIOSIS
Dispersal andgermination
Dispersal andgermination
ASEXUAL REPRODUCTION
Mycelium
Sporangia
• The zygomycetes are named for their sexually produced zygosporangia
• Zygosporangia are the site of karyogamy and then meiosis
• Zygosporangia, which are resistant to freezing and drying, can survive unfavorable conditions
• Some zygomycetes, such as Pilobolus, can actually “aim” their sporangia toward conditions associated with good food sources
© 2011 Pearson Education, Inc.
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.
Ascomycetes
• Ascomycetes (phylum Ascomycota) live in marine, freshwater, and terrestrial habitats
• Ascomycetes 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.
• Ascomycetes include plant pathogens, decomposers, and symbionts
• Ascomycetes reproduce asexually by enormous numbers of asexual spores called conidia
• Conidia are not formed inside sporangia; they are produced asexually at the tips of specialized hyphae called conidiophores
• Neurospora crassa, a bread mold, is a model organism with a well-studied genome
© 2011 Pearson Education, Inc.
Conidia;mating type ()
Mating type ()
DispersalGermination
ASEXUALREPRODUCTION Hypha
Conidiophore
Mycelium
Germination
Ascocarp
Dispersal
Asci
Mycelia
Eightascospores
SEXUALREPRODUCTION
Fourhaploidnuclei MEIOSIS
Diploid nucleus(zygote)
KARYOGAMY
Dikaryotichyphae
Ascus(dikaryotic)
PLASMOGAMY
Key
Haploid (n)
Diploid (2n)
Dikaryotic (n n)
Figure 31.17
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.
• The life cycle of a basidiomycete usually includes a long-lived dikaryotic mycelium
• In response to environmental stimuli, the mycelium reproduces sexually by producing elaborate fruiting bodies called basidiocarps
• Mushrooms are examples of basidiocarps• The numerous basidia in a basidiocarp are
sources of sexual spores called basidiospores
© 2011 Pearson Education, Inc.
Key
Haploid (n)
Diploid (2n)
Dikaryotic (n n) Mating type ()
Mating type ()
Haploidmycelia
SEXUALREPRODUCTION
Dispersal andgermination
Basidiospores(n)
Basidium withfour basidiospores
Basidium containingfour haploid nuclei
Basidium
Basidiospore1 m
MEIOSIS
Diploidnuclei
KARYOGAMY
Basidia (n n)
Basidiocarp (n n)
Gills linedwith basidia
DikaryoticmyceliumPLASMOGAMY
Figure 31.19
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.
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– Most endophytes are ascomycetes
© 2011 Pearson Education, Inc.
Figure 31.21
Endophyte not present; pathogen present (EP)
Both endophyte and pathogen present (EP)
EP EPEP EP
30
20
10
0
15
10
5
0
Lea
f m
ort
alit
y (%
)
Lea
f ar
ea d
amag
ed (
%)
RESULTS
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.
• 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.
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
SixtyLakeBasin
Yellow-legged frogskilled by B. dendrobatidisinfection
KeyBoundary of chytrid spread
Lake status in 2009:
Frog population extinct
Treatment lake: frogstreated with fungicidesand released
N
2004
2005
2006
20082007
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.
Figure 31.UN06
FungalPhylum
Distinguishing Features ofMorphology and Life Cycles
Chytridiomycota(chytrids)
Flagellated spores
Zygomycota(zygote fungi)
Resistant zygosporangiumas sexual stage
Glomeromycota(arbuscularmycorrhizalfungi)
Arbuscular mycorrhizaeformed with plants
Ascomycota(ascomycetes, orsac fungi)
Sexual spores (ascospores)borne internally in sacscalled asci; vast numbersof asexual spores (conidia)produced
Basidiomycota(basidiomycetes,or club fungi)
Elaborate fruiting body(basidiocarp) containingmany basidia thatproduce sexual spores(basidiospores)