Mycology

Fungi, fungi, biological characteristics, significance

LIVING THINGS

• 3 DOMAINS of Life:– BACTERIA

• Prokaryotic Cells

– ARCHAEA• Prokaryotic Cells

– EUKARYA• Eukaryotic Cells

(Semi-Living Things)

• Viruses– Non-cellular

Domain Eukarya

• Kingdom Protista– Single-celled, Autotrophs or Heterotrophs, variable

• Kingdom Plantae– Multicellular (mostly), Autotrophs, “Producers”

• Kingdom Animalia– Multicellular (mostly), Heterotrophs, “Consumers”

• Kingdom Fungi– Multicellular (mostly), Heterotrophs, “Decomposers”

Mycology• Mycology – from Greek “mykes” = mushroom,

cap & “logos” = discourse, study.

• Fungus (Fungi) – Latin, from the greek “Sphongous” = sponge-like, spongy.

Mycology• Mushrooms, Toadstools, Boletes, Yeasts,

Molds, Mildews, Puffballs, Stinkhorns….

FUNGI

• Huge group of very successful organisms – found in virtually all ecological niches on Earth.

• Largest single organism on Earth is a fungus. (Armillaria ostoyae)

• ~100,000 species* so far described, but there are likely many more (up to 2 million).– Inadequate sampling– *Species? Individual?

• Traditionally, fungi (particularly mushrooms) have been studied by botanists, however, they are “achlorophyllous”.

Fungi vs fungi• Fungi are a monophyletic (closely related) group

of organisms all sharing a common ancestry and evolutionary history, and sharing many common characteristics.

“TRUE Fungi”

• fungi are organisms that share many characteristics with Fungi (and so superficially resemble them), but DO NOT share a common ancestry and evolutionary history.

“fungus-like organisms”

FUNG-ISMS

• Myco…• …mycetes • …mycota• …mycotina

• Pathogenic/pathogen vs free-living• Dimorphism (Anamorph, Teliomorph ---

Holomorph)

Characteristics of Fungi• Heterotrophic (Saprobic or Parasitic)

– Extracellular digestion • Enzymes (hydrolytic, proteases, etc.) break down

macromolecules dimers & monomers.• These digestion products are then absorbed.

– An adaptive morphology allows for sufficient surrounding of food and sufficient energy intake to counteract the energy spent in digestive enzyme production…

Characteristics of Fungi• Most are filamentous

(adaptive morphology for increased surface area).– Vegetative body called a

Mycelium (pl. Mycelia).– A Mycelium is composed

of numerous Hyphae (sing. Hypha), each 1 cell wide.

Characteristics of Fungi• Some are small “uni-cells”

• Yeasts• Chytridiomycota

Yeasts

Chytrids

Filamentous Stage

Characteristics of Fungi

Cell Wall

Characteristics of Fungi• Cell Wall is composed of Chitin.

– Complex, N-containing Polysaccharide (a carbohydrate polymer).

– Helps maintain osmotic pressure in the cells.

Characteristics of Fungi• The vegetative (somatic) body of a fungus

is the Mycelium: the absorptive, “adult”, feeding stage.

Hyphae• Septa (sing. Septum) are partitions between

hyphal cells.

• Aseptate taxa are coenocytic (multi-nucleate).

• Septate taxa typically have a Septal Pore.

Characteristics of Fungi

• Rhizomorphs – root like masses of hyphae.

Characteristics of Fungi• A fraction of the vegetative mycelium is

devoted to reproduction.

• Specialized hyphae bearing Spores.

• Spores are tiny propagules.

Spores

• Dispersal• Protection• Survival• Reproduction.

• Asexually-produced spores are disseminative.

• Sexually-produced spores are reproductive AND disseminative.

Asexually-Produced Spores

• Spores are borne on hyphal tips called Conidia (sing. Conidium) or in Sporangia (sing. Sporangium).

Asexually-Produced Spores

• Produced by Mitosis & Cell Division.

• Clones (genetically-identical progeny) are produced.

Sexually-Produced Spores

• Spores are borne on unique and specialized structures, depending on the type of fungus.

• Produced by Meiosis & Cell Division.

• Genetically-unique progeny are produced.

• Sexual Reproduction = combined genetic contributions of two parents.

• Life cycles.

Life Cycles

MEIOSIS FERTILIZATION

HAPLOID STAGE (1N)

DIPLOID STAGE (2N)

Gametic Life Cycle

1N

2N

Gametic Life Cycle

• Meiosis produces gametes (sperm or egg).

1N

2N

Zygotic Life Cycle

• Meiosis produces spores (mini-zygotes).

1N

2N

(Spores)(Gametes here produced by Mitosis)

Classification of Fungi

Classification of Fungi• Fungi comprise a monophyletic group

broken into 4 lineages (therefore also 4 Phyla):

– Phylum: Chytridiomycota

– Phylum: Zygomycota

– Phylum: Ascomycota

– Phylum: Basidiomycota• “Phylum”: Deuteromycota is an artificial group

representing fungi that do not or have yet to exhibit a sexual stage (meiosis & syngamy).

Phylogeny of Fungi

MorphologicalCharacter statechanges

Chytridiomycota (chytrids)

Chytridiomycota

• Swimming Zoospores.

FUNGI

Zygomycota

The “Bread Molds”

• Sporangium (sporangia)– Asexual spores

Zygomycota

Zygomycota

• Zygospore– Sexual “spore”

(Suspensors)

Zygomycete Life Cycle

“Glomeromycetes”• Mycorrhizal Fungi

– (Endomycorrhizal)– VAM fungi: Vesicular-Arbuscular Mycorrhizae

FUNGI

Ascomycota

The Sac FungiMorchella esculenta

Ascomycota• Ascus (sac) is where the sexual spores

(Ascospores) are borne.

• 8 Ascospores are typical in each ascus.

Ascomycete Life Cycle

FUNGI

Basidiomycota

The ‘Club’ Fungi

Basidiomycota• Sexual Basidiospores borne on a Basidium.

• 4 spores per Basidium.

Basidium

Basidiospores

Basidiomycete Life Cycle

Studying FUNGI• Both Macroscopic and Microscopic

organisms.

• Cultures– 1-member, 2-member– Growth Media (sing. Medium)

• Agar, Broth

– Petri Plates or Culture Tubes.

Significance & Importance1. Sources of important chemicals

– Medicines.• Antibiotics like Penicillin, Cephalosporin.• Eastern Medicine, herbal remedies, anti-tumor, etc.

– Metabolites• Plant growth hormones, steroids.

– Mycotoxins, biological control agents.– Transformative enzymes.

• Alcohol fermentation with CO2 production by Saccharomyces cerevisiae (yeast).

• Cheese ripening, sausage production, miso

Significance & Importance2. Food sources.

– Mushrooms• Shiitake, Oyster, Porcini, Portobello, Morel, Truffle…• Wild Mushrooms….Poisonings.

– Cheeses, Miso, Beer, Wine, Bread.

– Cultivation…by humans and other animals.

3. Spiritual ceremony & shamanism.– Natives of Mexico & Central America – hallucinogenic

religious rites involving Psilocybe cubensis. (more recently studied by Wasson, McKenna, & others).

– Mushroom effigies associated with many primitive (& modern) cultures.

Significance & Importance4. Ecosystem Contributions

– Decomposers of cellulose, lignin (wood).(often found in human-manufactured items)

– Control of nutrient cycling.– Soil retention.– Mycorrhizal associations with plants.

5. Plant pathogens– Potato blight (Oomycete)– Chestnut blight (Cryphonectria parasitica)– Dutch elm disease (Ophiostoma sp.) – Ergot of Rye (Claviceps purpurea)

Significance & Importance

6. Animal Pathogens– Insects (Oomycetes, Laboulbeniales,

Septobasidium). – Humans (‘mycoses’)

• Ringworm, histoplasmosis, yeast infections.

7. Scientific “lab rats”– Especially Genetics

• Schizophyllum commune, Neurospora

THINK LIKE A FUNGUS

• How do I get food?

• How can I compete?

• How can I protect myself?

• What associations with other organisms are important?