mycology fungi, fungi, biological characteristics, significance
TRANSCRIPT
LIVING THINGS
• 3 DOMAINS of Life:– BACTERIA
• Prokaryotic Cells
– ARCHAEA• Prokaryotic Cells
– EUKARYA• Eukaryotic Cells
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.
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 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.
Zygotic Life Cycle
• Meiosis produces spores (mini-zygotes).
1N
2N
(Spores)(Gametes here produced by Mitosis)
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).
“Glomeromycetes”• Mycorrhizal Fungi
– (Endomycorrhizal)– VAM fungi: Vesicular-Arbuscular Mycorrhizae
Ascomycota• Ascus (sac) is where the sexual spores
(Ascospores) are borne.
• 8 Ascospores are typical in each ascus.
Basidiomycota
The ‘Club’ Fungi
Basidiomycota• Sexual Basidiospores borne on a Basidium.
• 4 spores per Basidium.
Basidium
Basidiospores
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