Fungal Diversity

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Fungal Diversity

• Reading Chap. 31
• I. Introduction
• A. What is a fungus?
• B. What does a fungus do?
• C. Basic fungal life cycle
• D. Who cares about fungi?
• II. Fungal Phyla
• A. Overview
• B-E. Life cycles of the phyla
• III. Fungal mutualisms
• A. Lichens
• B. Mycorrhizae

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A. What is a fungus?

• The humongous fungus

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A. What is a fungus?

• The parts

Fig. 31.1
Cell walls - made of chitin. Same material that
is in the external skeletons of arthropods -
insects, arachnids, and crustaceans.
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A. What is a fungus?

• Also yeasts - single-celled
• e.g., Saccharomyces cerevisiae
• Candida albicans

31.15
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B. What does a fungus do?

• Absorptive heterotroph
• Such as

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Also eat - wood in houses, boats, fences -
food - other materials - cloth, paint, leather,
waxes, jet fuel, petroleum, paper, wire
insulation, photographic film, - to name a few.
What do all of these materials have in common?
They are all C-based.
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C. Basic fungal life cycle
1. Zygotic - haploid phase is dominant
fig. 13.5b
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C. Basic fungal life cycle
2. Fertilization doesnt happen all at once
Plasmogamy - fusion of cytoplasm Karyogamy -
fusion of nuclei (gametes) heterokaryotic dikaryo
tic
fig. 31.2
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C. Basic fungal life cycle
3. Usually not identifiable male and female
individuals
draw
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D. Who cares about fungi?

• 1. Decomposers

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D.2. Agricultural pests
ergot
Stem rust
Pink ear rot
Parasites
Food spoilage
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D.3. Food - morels, truffles, shitakes, common
button mushrooms
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D.4. Medicinals

• Penicillium, etc.
• and hallucinogens
• - Psilocybin
• - ergot (LSD)

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D.5. Yeast for brewing and baking Saccharomyces
cerevisiae
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II. Fungal Phyla

• A. Overview
• 1. Common eukaryotic ancestor with animals

fig. 28.8
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II. Fungal Phyla

• A. Overview
• 2. Four phyla of fungi

fig. 31.4
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B. Zygomycota

• 1. No dikaryotic growth
• 2. Both sexual and asexual sporangia

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B. Zygomycota

• 3. Examples
• - Rhizopus (fig. 31.6)

31.8
Pilobolus
Many endomycorrhizae, too (e.g., Glomus)
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C. Ascomycota sac fungi or cup fungi
Scarlet cup
Morels
Truffles
Many lichen fungi too!
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C. Ascomycota - Life cycle
1. Dikaryotic growth 2. Fruiting body
ascocarp 3. Fertile layer with asci 4. Eight
ascospores per ascus (sac) 5. Asexual
reproduction via conidia
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D. Basidiomycota - club fungi
Hygrophorus
Shelf or bracket fungus
31.11
Stinkhorn fungus
Many mushrooms are ectomycorrhizal.
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D. Basidiomycota - Life cycle
1. Dikaryotic growth 2. Fruiting body
basidiocarp 3. Fertile layer on gills with
basidia (clubs) 4. Four spores per
basidium 5. Asexual reproduction is rare
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D. Basidiomycota - structure
2. Fruiting body basidiocarp 3. Fertile layer on
gills with basidia (clubs) 4. Four spores
per basidium
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E. Deuteromycota - fungi imperfecti

• 1. Not a true phylum (not a natural group)
  polyphyletic
• 2. Fungi with no known sexual reproduction
• 3. Asexual reproduction by conidia

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III. Fungal mutualisms
Definitions Symbiosis - 2 organisms living
together in intimate physical contact Mutualism
- both organisms benefit from the
relationship Parasitism - one benefits, one
loses Commensalism - one benefits, other not
affected
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III. Fungal mutualisms

• Questions
• 1. Definition of mutualism vs. symbiosis
• 2. What fungal and photosynthetic partners are
  involved?
• 3. What is the currency of the mutualism? How
  do the partners benefit?
• 4. What is the structure and/or morphology of the
  organismal interaction?
• 5. What is the ecological importance?

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A. Lichens
1. Partners a. Fungal partner - gives
protection - mostly Ascomycetes (25,000
spp.) - only found in lichens (not
free-living) b. Photosynthetic partner -
gives fixed carbon (sugars) - green alga or
cyanobacterium - can be free-living
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A. Lichens
a. most of lichen body is fungal hyphae b.
photosynthetic partner in a distinct layer c.
sexual reproduction of fungal partner only d.
asexual reproduction soredia, fragmentation
2. Anatomy
medulla
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A. Lichens
3. Morphology
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A. Lichens

• 4. Importance
• a. rock weathering, soil formation in primary
  succession
• - acid secretion
• - trapping particulates
• - nitrogen fixation (cyanobacteria)

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A. Lichens

• 4. Importance
• b. winter food for caribou and reindeer in Arctic

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A. Lichens

• 4. Importance
• c. Indicators susceptible to pollutants

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B. Mycorrhizae

• mycor fungus, rhizae root
• 1. Partners
• a. Fungus
• - gets fixed carbon (sugars)
• - both Zygomycetes and Basidiomycetes (a few
  Ascos)
• - relatively few Zygos not plant species
  specific
• - many Basidios fairly plant species specific

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B. Mycorrhizae

• 1. Partners
• b. Plant
• - gets nutrients (mostly P) and water
• - about 80 of all plant species are mycorrhizal!!

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B. Mycorrhizae

• 2. Structure two types of fungal/plant contact
• a. external (ectomycorrhizae)
• - fungal sheath around root
• - Basidiomycetes and about
• 5000 plant species (mostly woody)

Smith 1999
Fig. 31.18
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B. Mycorrhizae

• 2. Structure two types of fungal/plant contact
• b. internal (endomycorrhizae)
• - hyphae penetrate root cells
• - Zygomycetes
• - 80 of all plants (many herbaceous)

Smith 1999
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B. Mycorrhizae

• 2. Structure fungal mycelium
• - dramatic increase in root surface area
• 10,0001

Raven et al. 1999
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B. Mycorrhizae
No mycorrhizae
With mycorrhizae

• 3. Benefits - is it worth it?

No mycorrhizae
With mycorrhizae
Fig. 31.19