Mycology: the study of Fungi

I. What is a mushroom?A. Heterotrophic - lack chlorophyllB. Reproduce via sporesC. Mushroom is the fleshy, fruiting

bodyD. Many fungi do not produce fleshy

fruiting bodies1. Athlete’s foot2. Bread mold3. Yeasts

E. Mushrooms belong to twosubdivisions:1. Basidiomycetes2. Ascomycetes

II. Mushroom AnatomyA. Basidia (basidium) - microscopic

club-shaped cell bearing spores onthe exterior

B. Asci (ascus) - sac like mother cellcontaining spores

C. Gilled Mushrooms1. Cap2. Gills3. Stalk4. Veil (annulus)5. Mycelium - vegetative structure

Basidia “club-like”

Ascus “sac-like”

III. Fungi and the EnvironmentA. Parasitic fungi - feed on living

organismsB. Saprophytic fungi - subsist on dead or

decaying matterC. Mycorrhizal fungi - form a symbiiotic

relationship with plant roots1. Mycelium forms a sheath of

hyphae around the rootlets wherenutrient exchange takes place

2. Host specificity

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

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

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

Root Hair

hyphae

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

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

-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 (Rhizopus) the Common Molds

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

Mushrooms

Jelly Fungi

Basidiomycete Fungi that all produce Basiospores

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 has never been observed

• Different from Ascomycetes because there is a definite lack of sexual reproduction, which is why they are called Imperfect Fungi

Penicillium fungi

Up Close

Crustose

Foliose

Fruticose

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