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
Filamentous Stage
Chytrids
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 (multinucleate).
• 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
HAPLOID STAGE (1N)
MEIOSIS
FERTILIZATION
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
(Gametes here
produced by
Mitosis)
(Spores)
2N
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
Morphological
Character state
changes
Chytridiomycota (chytrids)
Chytridiomycota
• Swimming Zoospores.
FUNGI
Zygomycota
The “Bread Molds”
Zygomycota
• Sporangium (sporangia)
– Asexual spores
Zygomycota
• Zygospore
– Sexual “spore”
(Suspensors)
Zygomycete Life Cycle
“Glomeromycetes”
• Mycorrhizal Fungi
– (Endomycorrhizal)
– VAM fungi: Vesicular-Arbuscular Mycorrhizae
FUNGI
Ascomycota
Morchella esculenta
The Sac Fungi
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.
Basidiospores
Basidium
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 & Importance
1. 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 & Importance
2. 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 & Importance
4. 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?