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Mycology: the study of Fungi
I. What is a mushroom?
A. Heterotrophic - lack chlorophyll
B. Reproduce via spores
C. Mushroom is the fleshy, fruiting
body
D. Many fungi do not produce fleshy
fruiting bodies
1. Athlete’s foot
2. Bread mold
3. Yeasts
E. Mushrooms belong to two
subdivisions:
1. Basidiomycetes
2. Ascomycetes
II. Mushroom Anatomy
A. Basidia (basidium) - microscopic
club-shaped cell bearing spores on
the exterior
B. Asci (ascus) - sac like mother cell
containing spores
C. Gilled Mushrooms
1. Cap
2. Gills
3. Stalk
4. Veil (annulus)
5. Mycelium - vegetative structure
Basidia “club-like”
Ascus “sac-like”
III. Fungi and the Environment
A. Parasitic fungi - feed on living
organisms
B. Saprophytic fungi - subsist on dead or
decaying matter
C. Mycorrhizal fungi - form a symbiiotic
relationship with plant roots
1. Mycelium forms a sheath of
hyphae around the rootlets where
nutrient exchange takes place
2. Host specificity
What do fungi “eat?”
• Decomposers break down complex molecules
into sugars or consume sugars found in
environment
Examples:
• common bread mold (eats carbs in bread)
• shelf fungi on logs (eats carbs in cell wall of wood)
• white button mushrooms in store (eats sugars and
cellulose in dung)
What do fungi “eat?”
• Symbiotic fungi receive their energy
(carbohydrates) directly from a plant or algal partner
Examples:
• mycorrhizal fungi (live on plant roots)
• lichens (contain algae)
What else do fungi “eat?”
• Predatory fungi, catch and
digest other organisms
(like nematodes)
But still absorptive nutrition! Just have to catch it
first…
Summary: What do fungi eat?
• Heterotrophs (cannot make their own food like
plants)
• Extracellular, absorptive nutrition secrete enzymes
outside of their bodies, “digest” the food outside of
their cells and then absorb the molecules into their
cells.
• Live in their substrate (food)
How is this similar to us? What consequences/
advantages does it have?
Lichens
Fungi are made of hyphae
(cells joined in thread-like strands)
Mushrooms are for sexual reproduction (~flowers)
Mycelium = body of the fungus
Hyphae = the “bricks” from which the mushroom
is built
Why should you care about fungi?
A few reasons:
• They make foods we like to eat
• Mycorrhizae are responsible for plant life on land and
high productivity rates
• They decompose wood and organic matter
• Penicillin and other medicines
• They’re just really cool!
Mycorrhizae
• “myco” = fungus and “rhiza” = root
• Symbiotic association between plant roots
and fungi
• Several different types of association (defined
by structure of fungus:plant interface)
Fungi can access more of the soil because
1. Hyphae are smaller than plant roots
Root Hair
Hyphae are
1/500th the
diameter of a
plant root hair
hyphae
Recap of mycorrhizal benefits
Fungi increase the water and
nutrients available to their plant
partners leading to:
•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
Fungi are important decomposers!
Fungi are the only organisms that can completely
decompose lignin (what makes wood hard)
Lignin must be broken down before any other
decomposition can occur (no fungi = no decomposition
by anyone).
Fungi also decompose
cellulose to glucose and play
a major role in the global carbon
cycle.
Penicillium
• growth of the bacteria
Staphylococcus aureus is inhibited in
the area surrounding the invading
penicillin-secreting Penicillium mold
colony.
• 1928 Dr. Andrew Fleming working at
St. Mary’s Hospital in London
noticed that mold growing on staph
bacterial culture plates had killed the
pathogen
Mushroom Poisoning
• Out of several thousand different kinds of wild
mushrooms in North America, only five or six are
deadly poisonous!
• Most cases of “mushroom poisoning” are a result
of allergies, overindulgence, or food poisoning
Amanita Toxins
• extremely serious; 50% fatality
• symptoms are delayed by 6-24
hours
• liver and kidney damage
• violent vomiting, bloody
diarrhea, and severe
abdominal cramps
• no known antidote
Muscimol
• one of the oldest
endotoxicants
• Symptoms appear 30
minutes - 2 hours
• Nausea and vomiting,
confusion, mild euphoria,
loss of muscular
coordination, sweating,
chills, hallucinations, or
convulsions
Psilocybin
•
hallucinogenic mushroom
played an important role in
religious rites of natives of
Mexico and Central America
•
symptoms similar to LSD
•
heightened color perception,
visual distortion, and
hallucinations; profound anxiety
Bread Mold – a
Zygomycete Fungi
Cup Fungi – Ascomycete Fungi
Note the cup shapes and
orange peel colour
Kingdom Fungi – you must know 5 Major Phyla
1. Phylum Zygomycota = the Bread Molds
Rhizopus – black bread mold
2. Oomycota = the Water Molds
Water mold, potato blight, mildew
3. Phylum Ascomycota = the Sac Fungi
Yeast, morels, truffles
4. Phylum Basidiomycota = the Club Fungi
Mushrooms, puffballs, bracket fungi, rusts, smuts,
toadstools
5. Phylum Deuteromycota = the Fungi Imperfecti
Zygomycota (Rhizopus) the Common
Molds
-are primarily decomposers
-asexual spores may be produced in sporangia
-sexual reproduction occurs between + and – strains forming
a 2n zygote; a zygospore develops and may lie dormant for a
long period of time; meiosis occurs just before germination
-only the zygote is diploid; all hyphae and asexual
spores are haploid
Zygomycota – common molds
The fungal mass of
hyphae, known as the
MYCELIUM
penetrates the bread
and produces the
fruiting bodies on top
of the stalks
Mycelia = a mass of hyphae or
filaments
Rhizoids = root-like hyphae
The zhizoids meet underground and mating occurs between
hyphae of different molds (SEXUAL REPRODUCTION)
Zygomycota (Rhizopus)
Basidiomycete or Club Fungi
Life Cycle of Basidiomycete Fungi
Bracket Fungi
Puff Balls
Basidiomycete Fungi that all
produce Basiospores
Jelly Fungi
Mushrooms
Other Basidiomycetes Rusts and Smuts
Rust
infecting
wheat leaves
Rust infecting
a Leaf
Whitrot Smut
digesting old wood
Deuteromycota – the Fungi Imperfecti
• Resemble Ascomycetes,
but their reproductive cycle
Penicillium fungi
has never been observed
• Different from
Ascomycetes because
there is a definite lack of
sexual reproduction, which
is why they are called
Imperfect Fungi
Up Close
Fruticose
Crustose
Foliose
Mycorrhizae
Mycorrhizae means “fungus-root”;
mutualistic relationship between
plant and fungi
The plant photosynthesizes while
the fungus more efficiently takes
up nutrients and water from the
rhizosphere than the roots would
alone.
Plant benefits include:
•Improved nutrient/water
uptake
•Improved root growth
•Improved plant growth and
yield
•Improved disease resistance
•Reduced transplant shock
•Reduced drought stress