BESC 204 Molds and Mushrooms Lecture Notes Flashcards

Fungi: The Mycota

• Fungi constitute their own kingdom.
• Their primary ecological function is degradation, recycling biomass, destroying structures, and sometimes destroying life.
• Example: Microstoma floccosa.

Fungi as Pathogens

• Pathogenic to plants, animals, and humans.
• Example: Aspergillus flavus.
• Also pathogenic to other fungi.
• Example: P.oligandrum attacking R. solani.
• Trichoderma virens is another example.

Fungi and Secondary Metabolites

• Fungi produce secondary metabolites.
• Many medicines are derived from fungi.
• Example: Amanita muscaria.

Fungi as Food

• Fungi are a source of food.
• Edible fungi examples include Morchella esculenta (morel mushrooms).

Fungi and Symbiotic Relationships

• Fungi engage in symbiotic relationships such as:
  • Lichens
  • Mycorrhizae
• Example: Coprinus disseminatus.

Fungi as Allergens

• Fungi can be allergens, contributing to Sick Building Syndrome.
• Examples: Stachybotrys chartarum and possibly Aspergillus niger.

Fungal Spore Germination

• Aspergillus nidulans spore germination is being studied.

Time Lapse of Oyster Mushroom

• Demonstration of fungal growth through a time-lapse video of the Blue Oyster Mushroom.

What is Mycology?

• Mycology is the study of fungi.
• The term originates from the Greek word "mykes" (mushroom) and "logos" (discourse).
• A mycologist is a scientist who studies fungi.

Kingdoms and Domains of Life

• The number of recognized kingdoms of life varies among scientists, with common counts being 5 or 6, but some propose up to 30.
• Fungi are classified in their own kingdom, separate from plants, animals, and bacteria.

Historical Classifications

• Linnaeus (1735): 2 kingdoms (Vegetabilia, Animalia).
• Haeckel (1866): 3 kingdoms (Plantae, Protista, Animalia).
• Chatton (1937): 2 empires (Prokaryota, Eukaryota).
• Copeland (1956): 4 kingdoms (Monera, Protista, Plantae, Animalia).
• Whittaker (1969): 5 kingdoms (Monera, Protista, Fungi, Plantae, Animalia).
• Woese et al. (1977): 6 kingdoms (Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia).
• Woese et al. (1990): 3 domains (Bacteria, Archaea, Eukarya).

Phylogenetic Tree of Life

• Woese's Three Domains: Bacteria, Archaea, and Eukaryote, based on rRNA sequence data.

Number of Fungal Species

• Approximately 100,000 fungal species have been described, with about 1,700 new species identified each year.
• Hawksworth's Estimate (1991, 2001):
  • Ratio of fungi to plant species in the British Isles is 6:1 (12,000 fungi vs. 2,000 flowering plants).
  • Estimates based on this ratio suggest 1.5 million species of fungi worldwide.
  • Only a small fraction of fungal species has been described, and at the current rate, it would take over 800 years to describe all extant species.
• More recent estimates, based on sequencing, suggest the number could be more than 5 million.

Definition of a Fungus

• Fungus (singular): A eukaryotic, heterotrophic organism, devoid of chlorophyll, with chitin in cell walls, that obtains its nutrients by absorption, usually reproduces by spores, and usually exhibits a pronounced polarization of growing cells.
• Fungi (plural).

Characteristics of Fungi

• Eukaryotic: Possessing cells with a membrane-bound nucleus.
• Prokaryotic: Lacking a membrane-bound nucleus.
• Most fungi are comprised of hyphae that elongate by tip growth.
• Hyphae collectively form the mycelium.

Hyphal Growth

• Hyphal growth in Neurospora crassa is studied.

Fairy Rings

• Fairy rings are naturally occurring rings or arcs of mushrooms.

Ringworm

• Ringworm is a fungal infection of the skin.

Size of Mycelium

• Mycelia can grow to be very large.
• The largest living thing is a fungus in Oregon, covering 2,200 acres (3.5 square miles), estimated to be 2,400 years old and 605 tons in mass (Armillaria ostoyae).

Heterotrophic Nutrition

• All fungi are heterotrophs with absorptive nutrition (saprotrophs).
• They lack chlorophyll and are not autotrophic.

Cell Wall Structure

• Unique cell wall structure containing chitin, a structural polymer of glucose.
• Plants have cellulose, and animals lack cell walls.

Cell Compartmentalization

• Fungi are multi-cellular organisms with a unique system of cell compartmentalization.

Septum Formation

• Septum formation in Neurospora crassa is being studied.
• Fungal hyphae of many species contain septa, which facilitate cell compartmentalization.
• This compartmentalization distinguishes fungi from other multi-cellular organisms.

Fungal Cells

• Exceptions: Yeasts are single-celled organisms, and many spores are single-celled.

Spores

• Spores are reproductive propagules, usually microscopic.

Types of Spores

• Sexual Spores (products of meiosis):
  • Ascospores
  • Basidiospores
  • Zygospores
  • Zoospores (meiotic)
• Asexual Spores (products of mitosis):
  • Zoospores
  • Sporangiospores
  • Conidia

Learning Objectives

• Discuss the kingdoms/domains of life.
• Define 'Fungus'.
• Understand the estimation of the number of fungal species in the world.
• Gain familiarity with introductory mycology terminology.
• Name the largest/oldest organism in the world.
• Explain what is meant by a cell compartment.

Fungal Classification

• How fungi are named and classified.
• Examples: Chytridiomycota and Blastocladiomycota.

Examples of Fungi

• Examples include Wood Ear, Turkey Tail, Orange Peel Fungus, Eyelash Fungus, Dog Vomit Fungus, Russula emetica, Stemonitis, P. coronata, Tilletia foetida, and Black spot of elm (Stegonophora ulmea).

Species Concepts

• Morphological Species Concept:
  • Organisms that look the same are considered the same species.
  • Most fungal species are defined this way.
• Biological Species Concept:
  • Interbreeding or potentially interbreeding natural populations constitute the same species.
  • Mating in the lab is often used to define species membership.
• Phylogenetic Species Concept:
  • Individuals of the same species share a genealogical relationship inferred by phylogenetic analysis.
  • Assumes monophyly.
• The most appropriate species concept depends on the taxa under investigation.

Fungal Phylogeny

• Major groups: Chytridiomycota, Zygomycota, Basidiomycota, Ascomycota.

Fungal Evolution

• Evolutionary adaptation of fungi over time.

Chytridiomycota

• Approximately 1000 described species.
• "True Fungi" with flagellate spores (Zoospores) in sporangia.
• Do not make hyphae.
• Thallus is coenocytic (septa are rare or absent).
• Cell walls contain chitin and cellulose.
• Mostly aquatic or soil-inhabiting saprobes, some are parasitic.

Chytridiomycota - Notable Species

• Batrachochytrium dendrobatidis: pathogen of frogs and toads, responsible for amphibian decline worldwide.

Chytridiales

• Olpidium brassicae: resting sporangia and zoospoorangia in rhizodermal cells.

Blastocladiales

• Blastocladiella emersonii: Differentiation of sporangium depending on CO2 levels; complex life cycle.

Chytridiomycota vs. Blastocladiomycota

• Chytridiomycota: no hyphae, zoospores.
• Blastocladiomycota: with hyphae (no septa), zoospores.

Blastocladiomycota

• Often referred to as 'Chytrids'.
• "True Fungi" with flagellate spores (Zoospores) in sporangia.
• They do make hyphae, septa are rare or absent.
• Complex life cycles.
• Mostly aquatic or soil-inhabiting saprobes.

Blastocladiomycota - Notable Species

• Allmoyces macrogynous: A zoosporic aquatic fungus that makes hyphae that lack septa, exhibits complex life cycle with alteration of generations.

Blastocladiales Life Cycle

• Alomyces macrogynus: Includes settlement of zygote, zygote germination, karyogamy, copulation, meiosis, and alternation of generations.

Learning Objectives Recap

• Know why Latin is used to name and describe species.
• Know the six major groups (phyla) of fungi (Chytridiomycota and Blastocladiomycota).
• Discuss similarities and differences between the six major groups.
• Know the name of the most common spores produced by each major group.
• Describe each of the three species concepts described in class and when to use each.
• Know the names of notable species.

Zygomycota and Zoopagomycota

• Examples: Strawberry-Rhizopus time lapse - Rhizopus stolonifer eating your bagel.

Zygomycota

• Unifying character: The Zygospore
• Asexual spores are sporangiospores made in a sporangium.
• With true hyphae that are mainly coenocytic, no septa in most newly developed hyphae.
• Terrestrial
• Cell walls have: Chitin, chitosan (non-acecylated chitan) and polyglucuronic acid
• Note: some authors call this group Mucoromycota

Typical Zygomycota

• Reproduces quickly
• Makes many offspring
• Utilizes simple sugars

Important Zygomycota

• Rhizopus stolanifer (Black bread mold; model system for mating)
• Phycomyces blakesleanus (model system for mating)
• Pilobolus spp. (fascinating spore discharge)
• Countless members of the Glomerales (90% of land plants form arbuscular mycorhizae with these fungi)

Rhizopus

• Asexual Sporagia
• Sexual Zygospores

Mating Type

• Discuss Mating Type. Here + and –
• Not the same as male and female, since + mating type can make male or female structures and – can make male or female structures.
• These + or – is determined by a single locus, with a different idiomorphic gene present at the locus for each.
• Heterothallic : requires two compatible thalli to produce sexual spores
• Homothallic : capable of sexual reproduction from a single thallus

Rhizopus Life Cycle

• Asexual and Sexual Reproduction

Rhizopus stolonifer

• Asexual development: growth of aerial hyphae, sporangium differentiation, disease symptoms

Rhizopus sexualis

• Sexual development: zygophore, progametangium, gametangium and zygospore

Phycomyces blakesleeanus

• Asexual development: sporangium development, positive phototropism, negative geotropism

Phycomyces blakesleeanus

• Sexual development: conjugation, progametangium, gametangium and zygospore formation

Phototropism of Pilobolus

• Aerial growth directed toward the light.
• Black spore mass at head of sporangium is ejected 3 meters after rupture of sub-sporangial vesicle.
• Parasitic nematode larvae crawl up sporangium are launched along with spores.
• Light sensing

Pilobolus

• asexual development: sporangiophore development, trophocyst development, sporangium differentiation

Acceleration Comparison

• 100m world record Usain Bolt = 3.072 m/s^2
• Acceleration of a top fuel drag racer = 15.8 m/s^2
• Acceleration of bullet form .357 magnum handgun = 3.2 \times 10^5 m/s^2
• Acceleration of Pilobolus sporangium = 2.1 \times 10^5 m/s^2

Zygomycota vs Zoopagomycota

• Zygomycota: hyphae, no septa, zygospores, sporangiospores
• Zoopagomycota: hyphae, no septa, zygospores, sporangiospores (~conidia), pathogens of animals

Zoopagomycota

• All make a ZYGOSPORE as the sexual spore
• Asexual spores are sporangiospores made in a sporangium…sporangia often germinate directly.
• With true hyphae that are mainly coenocytic, no septa in most newly developed hyphae.
• terrestrial
• Most are typically insect or other animal pathogens.

Important Zoopagomycota

• Basidiobolus ranarum (Pathogen of animals -humans)
• Entomophthora muscae (Insect pathogen)

Learning Objectives Recap

• Know the six major groups (phyla) of fungi (Zygomycota and Zoopagomycota today)
• Be able to discuss similarities and difference between the six major groups
• Know the name of the most common asexual and sexual spores produced by each major group
• Be able to describe the spore discharge mechanism of Pilobolus
• Be familiar with the life cycle of Rhizopus as a means of understanding asexual and sexual reproduction
• Understand mating type with respect to the Zygomycota

Ascomycota and Conidiating Fungi

• Discussing Ascomycota and deuteromycota (conidiating fungi)

Ascomycota

• Production of an Ascus (Asci plural)
• An Ascus is a sac-like structure filled with ascospores
• Contains approximately 75% of the described species
• The Most diverse and arguably the most important phylum

Ascomycota Characteristics

• Have regularly spaced septa (usually with a central pore)
• Cell walls contain chitin and glucans
• Never produce motile spores
• When produced, conidia (the asexual spores) are never produced by cytoplasmic cleavage in a sporangium

Ascomycota Phylogeny

• Certainly a monophyletic group
• Common ancestor circa 300-500 million years ago
• Closely related to the Basidiomycota

Ascomycota Reproduction

• Generally Ascomycetes are thought to reproduce both sexually and asexually
• Some have only a sexual state known while others have only an asexual stage known.

Ascomycota characteristics

• Thallus varies from single-celled to well-developed mycelium with regularly spaced septa. Most septa possess a single central pore.
• Small spherical structures called Woronin bodies which are typically associated with each septum. Some yeasts have septa with micropores similar to a sieve

Woronin bodies

• Spherical structures associated with the septum in ascomycetes

Textbook Ascus formation

• Gametangial Contact/ Fusion

Ascus formation process

• Diagrams illustrating the process of ascogonium and antheridium fusion leading to ascus formation

Crozier formation

• asci initial

General life cycle

• Diagram illustrating a generalized life cycle

Types of Ascocarps

• Perithecium (perithecia pl.) a closed ascocarp with a pore (ostiole) at the top, and a wall of its own.

Ascocarp Variety

• Apothecium (apothecia pl.) an open ascocarp

Ascocarp Variety

• Cleistothecium (cleistothecia pl.) a completely closed ascocarp

Ascocarp Variety

• Ascostroma (ascostromata pl.) a stromatic ascocarp bearing asci directly in locules within the stroma (also called pseudothecium)
• Locule a cavity within a stroma
• Stroma a somatic structure on which or in which fructifications are formed

Examples of Ascomycota

• Chlorociboria sp.
• Bulgaria inquinans

Examples of Pezizales

• Cookeina sp.
• Sarcoscypha coccinea
• Urnula sp.
• Aleuria aurantia, the orange peel fungus
• Scutellinia scutellata, its orange apothecia rimmed with dark hairs

Ascobolus

• The ascus and ascospore discharge

Truffles

• Tuber texenses

Mitosporic Fungi

• Deuteromycota (Ascomyctoa)

Ascomycetes Sexual/Asexual Stages

• Sexual Stage= “perfect” stage or Meiotic stage produceing meiospores
• Asexual Stage= “imperfect” stage or Mitotic stage produceing mitospores

Mitosporic Fungi

• What is a conidium ? Conidia plural
• Conidium a non-motile, asexual spore formed ‘one at a time’ of a conidiogenous cell.
• Cell wall of conidium and the conidiogenous cell is continuous.
• They are not formed by cleavage of cyotplasm as is the case for sporangiospores and zoospores we have already encountered in the class. Consequently they are not surrounded by an additional sporangial wall.

Holomorph Terms

• Holomorph, Anamorph, Teleomorph concept:
  • Holomorph = All forms (morphs) of the fungus, either latent or expressed
  • Anamorph = Asexual (imperfect, mitotic) form(s)
  • Teleomorph = Sexual (perfect, meiotic) form
• To properly classify a fungus, you must know its teleomorph. If no sexual stage is known, then the fungus must be given a temporary name based upon its asexual stage and placed in the Deuteromycota/ Mitosporic Fungi. If a sexual stage is discovered then the species must be renamed and placed in the appropriate phylum.

Conidia formation

• Formation of conidia in Erysiphales; basipetal, blastic

Condiophores

• Development in Apergillus nidulans

Conidiphore Development

• Conidiogenesis is phialidic, blastic, basipetal

Learning Objectives Recap

• Know the major groups of fungi (Ascomycota today)
• Be able to discuss similarities and difference between the major groups
• Know the name of the most common asexual and sexual spores produced by each major groups
• Be able to explain the holomorph, teleomorph, anamorph concept
• Know the general life cycle for the Ascomycota
• Know the four types of ascocarp described today
• Know the difference between conidia and sporangiospores
• Know the anamorph, teleomorph, holomorph concept

Introduction to Basidiomycotas

• Examples include Tremella mesenterica, Clavicorona pyxidata, Amanita muscaria, Mutinus elegans, Marasmiellus nigripes, Lycoperdon pyriforme

Characteristics of Basidiomycota

• Produce a Basidium. Usually produced on a macroscopic Basidiocarp.
• Production of a well developed septate mycelium
• Production of clamp connections in some species
• Presence of Dolipore septa in some species
• Extended dikaryotic stage

Septal Pores

• Dolipore septa, septal pore caps or parenthosomes

Septa types

• Ascomycetes, Holobasidiomycetes, Dolipore

Clamp Conections

• Clamp Connection Formation

Basidia

• Basidia and Basidiospores

Basidium Development

• Meiosis and Basidiospore Formation

Ascus vs Basidium

• Comparison of Ascus and Basidium

Commonlities

• Compartmentalized mycelium
• Dikaryotic Stage (But it is extended in Basidiomycetes)
• Specialized Spore producing tissues. (The hymenium)
• Production of conidia (though this is rare in Basidiomycota)

Life Cycle

• Video explaining the life cycle of the Basidiomycota

Basidoimycota Variety

• Adaptation

Basidocarp variety

• Agarics - The hymenium is found on surface of gills

Basidiocarp variety

• Boletes―hymenium lines pores or tubes, fleshy basidiocarp

Basidiocarp variety

• Chanterelles - hymenium on gill-like folds

Basidiocarp variety

• Toothed fungi - hymenium on small spines

The Stinkhorns

• The Stinkhorns; best known for the fetid odor they produce at spore maturity

Spore Release

• Spores not discharged at maturity as with Ballistospores and are therefore sometimes referred to as Statismospores.
• They simply fall off of their Basidia/Sterigma at maturity into the spore mass of the Gleba.

Examples

• The Puffballs and earthstars.

Bean Rust

• Uromyces appendiculatus

Fungal haustoria

• Hyphae that penetrate the cell walls of a host

Rust

• Urediniospore Germlings

Microfabricated

• Defined the topographical signal inductive for initiation of appressoria.

Learning Objectives Recap

• Be able to discuss similarities and difference between the six major groups
• Know the name of the most common asexual and sexual spores produced by each major groups
• Be able to define terminology introduced in class today examples: Clamp connection, dikaryon, dolipore septum, basidiospore,
• basidium, appressorium
• Be able to describe how rust fungi are triggered to form an appressorium
• Know commonalities between Asco- and Basidiomycota
• Know the characteristics of the Basidiomycota