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 comparisonChallenge Plants Fungi Animals

Energy

Water/ avoid

Desiccation

Reproduction

Cells

What do fungi “eat?”

• Decomposers break down complex molecules into sugars or consume sugars found in environmentExamples:

• 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?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 • BreadMushrooms• White button,

crimini,portabella• Truffles, chanterellesMycoprotein(food additive like tofu)

Cheese •Rennin, •blue cheeseSoy sauceTempehCitric 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)

Do pine seedlings grow better with a mycorrhizal (fungal) partner?

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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

Hyphae are 1/500th the diameter of a plant root hair

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 benefitsFungi 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 fungiRight: 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)

Ectomycorrhizae

~5,000-10,000 species of fungi

Conifer trees, oaks, birches, beeches, Eucalyptus)

(~2000 species of trees)

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.