Transcript Introduction to the Fungi

Introduction to the Fungi
Some things you should know……
Goals for today
•What are fungi?
• How do fungi interact with other
organisms?
•Why should you care about fungi?
Think for a minute, then write down your
opinion of fungi on the slip of paper you
were given when you came in
•
Discussion
Question
Which of the
following is
most closely
related to a
mushroom
(fungus)?
Why do you think
so?
Kingdom comparison
Challenge
Energy
Water/ avoid
Desiccation
Reproduction
Cells
Plants
Fungi
Animals
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
Absorptive nutrition makes lichens
good indicators of air quality
Small Group Discussion
Question
The white mushrooms comprise how
many fungal individuals?
•
•
•
one
42
420
What is the same
in these two
photos?
What does
a fungus
body look
like?
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
Recap: Definition of fungus
• Single or multi-celled eukaryote with
heterotrophic, absorptive nutrition,
chitinous cell walls, and which stores
energy as glycogen
• Live in food source or go dormant in low
humidity
Discussion Question
How big are fungi?
A. Microscopic (too small to see)
B. Small (can hold in your hand)
C. About as big as people
D. Larger than a house
Example of a “humungous
fungus”
• Armillaria bulbosa – a
mushroom producing
wood decomposer
• Covers at least 38 acres in
a forest in Michigan
• Estimated to weigh 100
tons (size of a blue whale)
• Estimated to be at least
1500 yrs old
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!
Examples of foods made
possible by fungi
Yeast
• Beer and Wine
• Bread
Mushrooms
• White button,
crimini,portabella
• Truffles, chanterelles
Mycoprotein
(food additive like tofu)
Cheese
•Rennin,
•blue cheese
Soy sauce
Tempeh
Citric acid
(soft drinks)
Why should you care about fungi?
A few reasons:
• They make foods we like to eat
• Mycorrhizae (plant:fungal symbioses
that forms on plant roots) 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)
seedling weight (g)
seedling height (cm)
% survival
Do pine seedlings grow better with a
mycorrhizal (fungal) partner?
Advantages to fungi
• Plants are a dependable and
abundant source of
carbohydrates
Advantages to plant
•
Fungi are better than plants at acquiring
mineral nutrition (P,K, N) from the soil.
•
Fungi improve a plant’s access to water
Because fungi
– can access greater soil volume
– can break molecules down into useable
forms
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
and fungi expand the surface area
available for nutrient uptake
Fungi are better at acquiring
nutrients because
2. Fungi have digestive enzymes that
plants do not (remember absorptive
nutrition)
– Can turn inorganic phosphorus and
nitrogen into forms usable by plants
Because fungi secrete their enzymes
outside of their cells (into the soil) they
can use “dangerous” enzymes which
produce too many free radicals to use
inside cells
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
What would happen if
a mycorrhizal fungus
grew from one plant
to another forming
mycorrhizae with
both?
Hyphae are long
“tubes” fungi are
good at acquiring
and moving
compounds
around.
Simard et al. (Nature 1997)
experimental setup
These connections can form
forest-wide networks!
Implication of fungal networks
• If mycorrhizae can move significant
amounts of carbon (sugar) between
different plant species, this could reduce
competition and contribute to the
stability and diversity of ecosystems.
Inadvertent “Parenting” in fungi
• Mycorrhizal connections also may move carbon from
dominant trees to shaded seedlings (based on the
same source sink relationship)
Are mycorrhizal
interactions between
plants and fungi
rare
or
common?
Almost ALL plant species depend
on mycorrhizae to some extent
2 of 6 Types of
mycorrhizae
Plant partners
Vesicular-arbuscular
(VAM)
~150 species of
fungi
Nearly all terrestrial plants
(200,000 species including
grasses, crops, flowering
plants, and flowering trees
not listed below)
Conifer trees, oaks, birches,
beeches, Eucalyptus)
(~2000 species of trees)
Ectomycorrhizae
~5,000-10,000
species of fungi
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!
What would happen if wood was
not decomposed?
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.
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!
Penicillium
WWI, bacterial
infections killed
more soldiers than
bullets.
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
zone of dead
bacteria
Penicillin kills bacteria by interfering with
their ability to synthesize cell wall.
Why do fungi make antibiotics?
Fungi produce
antibiotics for the
same reason we
need them:
to fight off
bacterial
infections
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 antibiotics
• They’re just really cool!
• This power point will be posted on my website for your
studying convenience.
• Please write down on your scrap paper
your “new” opinion of fungi
• Please turn in scrap paper answers as
you exit.