Fungi
Fungi
Kingdom:
Fungi (Eumycota)
•  Sphongos (Greek: ): “spongy”
-> Fungus (Latin): “mushroom”
•  Mycos (Greek): “mushroom”
•  Mycology: the study of fungi
Kingdom:
Fungi (Eumycota)
•  Eukaryotic
Kingdom:
•  Multicellular (most) with limited differentiation
•  Chitinous cell walls
Fungi (Eumycota)
Fungal mycelium (body) is comprised of
many hyphae (tubular filaments)
Reproductive structure
Hyphae
•  ~100,000 named species
§ 
~ a third with unclear taxonomy
Spore-producing
structures
•  Heterotrophic with external digestion
•  Haploid life history
60 µm
Mycelium (a mass of hyphae)
Kingdom: Fungi
Hyphae are septate or coenocytic
Kingdom:
Fig. 31.2
Fungi
Heterotrophic
Absorb nutrients from environment
Secrete exoenzymes for external digestion
Most are saprobic
Major decomposers
Many are parasitic
Many are mutualistic symbionts
Some are predatory!
Heyer
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Fungi
Penicillium
Symbiotic Fungi
1.5 µm
Saprobic Fungi
• Hyphae penetrate soil or decaying tissues
• Erect sporangia to disperse spores
• Present in many symbiotic (incl. parasitic) species
• Specialized branches off of hyphae
• Note: penetrate cell wall, but not plasma membrane
Haploid Life History
Predatory Fungi
Key
Haploid (n)
Heterokaryotic
(unfused nuclei from
different parents)
Diploid (2n)
KARYOGAMY
(fusion of nuclei)
SEXUAL
REPRODUCTION
Zygote
Mycelium
Digestive hyphae have removed
all the worm tissue from this
empty cuticle
• Hyphae specialized into adhesive nets or
constricting slip-rings
• Prey are nematodes (soil round worms)
General Lifecycle of Fungus
• Only zygote is diploid
• Zygote immediately undergoes meiosis
to form haploid daughter cells
- usually as spores (meiospores)
MEIOSIS
GERMINATION
Spores
Spore-producing
structures
• Source of protein to supplement calories
obtained from decomposing cellulose
Haploid Life History
& karyogamy
Haploid Life History Plasmogamy
may be separated by
Key
Haploid (n)
Heterokaryotic
(unfused nuclei from
different parents)
Diploid (2n)
Fig. 31.5
hours to decades!
Key
Haploid (n)
Heterokaryotic
(unfused nuclei from
different parents)
Diploid (2n)
PLASMOGAMY
(fusion of cytoplasm)
Heterokaryotic
stage
PLASMOGAMY
(fusion of cytoplasm)
KARYOGAMY
(fusion of nuclei)
SEXUAL
REPRODUCTION
Zygote
Mycelium
General Lifecycle of Fungus
GERMINATION
• 
Haploid spores form haploid hyphae
• 
May mate with haploid hyphae from
Spores
another mycelium
• 
Same species, but different mating type
• 
Prevent mating with its own hyphae
• 
Attracted by pheromones
Heyer
KARYOGAMY
(fusion of nuclei)
SEXUAL
REPRODUCTION
Zygote
Mycelium
MEIOSIS
Spore-producing
structures
Fig. 31.5
General Lifecycle of Fungus
GERMINATION
*  Mating divided into two steps
1.  Plasmogamy: fusion of plasma membranes
Spores
• 
Produces heterokaryotic cell
• 
Divide to form heterokaryotic hyphae
2.  Karyogamy: fusion of dikaryotic nuclei
• 
Produce diploid zygote
MEIOSIS
Spore-producing
structures
Fig. 31.5
2
Fungi
Haploid Life History
Key
Haploid (n)
Heterokaryotic
(unfused nuclei from
different parents)
Diploid (2n)
Heterokaryotic
stage
PLASMOGAMY
(fusion of cytoplasm)
KARYOGAMY
(fusion of nuclei)
Spore-producing
structures
Spores
ASEXUAL
REPRODUCTION
SEXUAL
REPRODUCTION
Fungal
Phyla
(Divisions)
Zygote
Mycelium
MEIOSIS
GERMINATION
General Lifecycle of Fungus
• Most fungi can also produce spores
asexually (conidiospores)
• (Many only produce spores asexually)
GERMINATION
Spores
Spore-producing
structures
Fig. 31.5
Zygomycota
Zygomycota
Fig. 31.12
•  >1,000 spp.
Hyphae are coenocytic
Rhizopus sp.
Rhizopus sp.
Zygomycota
Zone of
Mycelium #1 &
Mycelium #2
mating –
zygosporangia
formation
fused hyphae
zygosporangium
Rhizopus sp.
Heyer
Mycelium #1
Asexual
sporangia from
Mycelium #1
Asexual
sporangia from
Mycelium #2
Mycelium #2
Rhizopus sp.
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Fungi
Ascomycota (sac fungi)
Ascomycota (sac fungi)
Fig. 31.16
•  >65,000 spp.
Cultures of soil ascomycetes
Hyphae are usually
septate & haploid
Ascomycota (sac fungi)
Basidiomycota (club fungi)
Fig. 31.18
Yeasts —
•  Single-celled
ascomycetes
Mushroom
Hyphae are usually
septate & dikaryotic
Basidiomycota (club fungi)
Basidiomycota (club fungi)
~30,000 spp.
Fruiting Bodies
Mushroom
Shelf Fungus
Heyer
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Fungi
“Fairy Rings”
Spores
Basidium
Transient fruiting bodies
(basiocarps) where the
periphery of one mycelium
encounters & mates with
surrounding mycelia.
Mushroom Gill
Ecological Importance
Decomposers
Able to decompose usually nondigestible polymers,
e.g., cellulose, lignin, waxes, chitin, keratin, etc.
Ecological Importance
Cause of disease: in animals (mycosis)
Yellow-legged frogs killed by chytrid infection
Athlete’s foot
Dermatophytosis
(“ringworm”)
Ecological Importance
Cause of disease: in plants
~30% of known fungal species are plant pathogens
Entamapathogenic fungus
Ecological Importance
Mutualistic Endophytic (within plants) Fungi
Found within the cell walls of nearly all plants, esp. in leaves.
•  Resistance to osmotic or temp stress
•  Produce toxins against consumers, esp. insects
•  Provide pathogen resistance
Endophyte Plant
Soil
Temp.
(Curvularia)
+ or –
# New
Mass (g) Shoots
Results
Endophyte not present; pathogen present (E−P+)
Leaf mortality (%)
E+
30
35°C
(b) Tar spot
fungus
on maple
leaves
(a) Corn smut on corn
20
40°C
Without endophytes
10
E–
E+
E–
E+
Leaf area damaged (%)
E–
16.2
30°C
Both endophyte and pathogen present (E+P+)
22.8
15
32
60
21.7
28.4
43
60
08.8
22.2
5
10
37
10
E–
00.0
00
45°C
0 Redman et al., Thermotolerance
E+
15.1
0
R. S.
generated
by plant/fungal24
symbiosis, E−P+
Science 298:E+P+
1581 (2002).
E−P+
E+P+
With endophytes
(c) Ergots on rye
Heyer
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Fungi
Ecological Importance
Symbiotic relationships: mycorrhizae
Mycorrhizae
• Decompose organic
matter in soil
– Free up inorganic
nitrogen &
phosphorus
compounds
• Produce organic
acids
– Dissolve minerals
from soil particles
• Increase surface
area to absorb water
& inorganic nutrients
Mycorrhizae
Ecological Importance
Ectomycorrhiza & Endomycorrhiza
Rhizosphere: special root environment
• Roots secrete substances • stimulate germination of
mycorrizzal spores & attract
growing mycorrizzal hyphae
• Mycorrizza secrete substances • stimulate growth of root tips
• Mycorrizza secrete volatile
organics • stimulate growth of beneficial
soil bacteria
Symbiotic relationships: lichens
Symbiotic relationships: lichens
Human Uses
Food
Heyer
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Fungi
Human Uses
Human Uses
Food Processing
Food
Warning:
Edible & poisonous
varieties are difficult
to distinguish!
Death cap, Amanita phalloides
>50% of mushroom poisonings
Destroying angel,
A. bisporiga
Even more deadly, but rarer
Esp. genus
Amanita
Fly agaric, A. muscaria
Insecticidal & hallucinogenic
Human Uses – Myco-Pharmaceuticals
Antibiotics
Penicillium
Zone of
inhibited
growth
Human Uses – Myco-Pharmaceuticals
Psycho-active mushrooms
• psilocybin / psilocin (serotonin analogs)
• adrenalin-like rush
• visual/auditory hallucinations
• Mesoamerican
mushroom stones
Bacteria
(Staphylococcus)
• Psilocybe zapotecorum.
Jalisco, Mexico
Human Uses – Myco-Pharmaceuticals
Statins
• Lower blood cholesterol
Human Uses
Bioremediation (Mycoremediation)
Clean up contaminated environments
• Decompose organic toxins
– petroleum, pesticides, plastics, etc.
• Accumulate inorganic toxins
– heavy metals, incl. radioactive wastes
• Lovastatin from Aspergillus terreus and Pleurotus ostreatus (oyster
mushroom)
Heyer
Oyster mushrooms used to clean up
2007 fuel oil spill in San Francisco Bay
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