Introduction to the Fungi

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Introduction to the Fungi
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Goals for today

• What are fungi?
• How do fungi interact with other organisms?
• Why should you care about fungi?
• Think for a minute, then discuss with your
  neighbor and write down whatever you can agree on

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• Small Group Discussion Question
• Which of the following is most closely related to
  a mushroom (fungus)?
• Why do you think so?

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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)

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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)

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What else do fungi eat?

• Predatory fungi, catch and digest other organisms
  (like nematodes)

But still absorptive nutrition! Just have to
catch it first
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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?

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Lichens
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Absorptive nutrition makes lichens good
indicators of air quality
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What is the same in these two photos?
What does a fungus body look like?
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Fungi are made of hyphae (cells joined in
thread-like strands)
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Mushrooms are for sexual reproduction
(flowers)Mycelium body of the fungus
Hyphae the bricks from which the mushroom is
built
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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

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Small Group Discussion Question

• How big are fungi?
• Microscopic (too small to see)
• Small (can hold in your hand)
• About as big as people
• Larger than a house

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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

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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
• Theyre just really cool!

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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)

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Why should you care about fungi?

• A few reasons
• They make foods we like to eat
• Mycorrhizae (plantfungal 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
• Theyre just really cool!

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Mycorrhizae

• myco fungus and rhiza root
• Symbiotic association between plant roots and
  fungi
• Several different types of association (defined
  by structure of fungusplant interface)

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Do pine seedlings grow better with a mycorrhizal
(fungal) partner?
seedling weight (g)
survival
seedling height (cm)
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Advantages to fungi

• Plants are a dependable and abundant source of
  carbohydrates

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Advantages to plant

• Fungi are better than plants at acquiring mineral
  nutrition (P,K, N) from the soil.
• Fungi improve a plants access to water
• Because fungi
• can access greater soil volume
• can break molecules down into useable forms

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Fungi can access more of the soil because

• Hyphae are smaller than plant roots

Root Hair
Hyphae are 1/500th the diameter of a plant root
hair
hyphae
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and fungi expand the surface area available for
nutrient uptake
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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
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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
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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.
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These connections can form forest-wide networks!
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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.

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Inadvertent Parenting in fungi

• Mycorrhizal connections also may move carbon from
  dominant trees to shaded seedlings (based on the
  same source sink relationship)

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• Are mycorrhizal interactions between plants and
  fungi
• rare
• or
• common?

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Almost ALL plant species depend on mycorrhizae to
some extent
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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
• Theyre just really cool!

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What would happen if wood was not decomposed?
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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.
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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
• Theyre just really cool!

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Penicillium
WWI, bacterial infections killed more soldiers
than bullets. 1928 Dr. Andrew Fleming working at
St. Marys Hospital in London noticed that mold
growing on staph bacterial culture plates had
killed the pathogen
zone of dead bacteria
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Penicillin kills bacteria by interfering with
their ability to synthesize cell wall.
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Why do fungi make antibiotics?
Fungi produce antibiotics for the same reason we
need them
to fight off bacterial infections
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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
• Theyre just really cool!

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Citation

• www.biol.sc.edu/timmerman/Intro20Fungi20Fall20
  2006.ppt