BIOL 6949: Cellular and Molecular Mycology

Fall 2011

Short Fungus Movie

What are Fungi?

BIOL 6949 (Spring 2011) Copyright © 2011 Chester R. Cooper, Jr. Disclaimer: This lecture slide presentation is intended solely for educational purposes. Many of the images contained herein are the property of the original owner, as indicated within the figure itself or within the figure legend. These images are used only for illustrative purposes within the context of this lecture material. Use of these images outside the purpose of this presentation may violate the rights of the original owner. Dr. Cooper and Youngstown State University assume no responsibility for the unauthorized use of the material contained herein.

BIOL 6949 (Spring 2011)

Fungi in the Tree of Life •  Living organisms on earth first arose about 3.5 billion years ago –  Prokaryotic –  Anaerobic

•  Oldest fossils of fungi are about 460 million years old Fossilized perithecium of what is believed to be a fungus of the genus Savoryella. Note the ascospores (arrow) within the ascocarp. Source: www.ucmp.berkeley.edu/fungi/fungifr.html

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in the Tree of Life (cont.) •  Each of these three kingdoms differ in their basic cellular structure and mode of nutrition (defined by Whittaker, 1969) –  Plants - photosynthetic, cellulosic cell walls –  Animals - digestive systems, wall-less cells –  Fungi - absorptive nutrition, chitinous walls BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in the Tree of Life (cont.) •  Coincides with the rapid expansion of multi-cellular organisms •  Major multicellular eukaryotes are divided into Kingdoms –  Animals –  Plants –  Fungi BIOL 6949 (Spring 2011)

Artistic vision of mushrooms among plants. Source: interactive.usc.edu/members/jchen/

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in the Tree of Life (cont.) •  The estimates for the expansion of multicellular organisms are based upon phylogenetic analyses of Carl Woese

Whittaker’s Five Kingdom System.

Copyright © 2011 Chester R. Cooper, Jr.

–  Examined ribosomal RNA (rRNA) •  Present in prokaryotes and eukaryotes •  Relatively stable, but changes occur over time; thereby acting as a chronometer –  Distinguished three separate groups (Domains) of living organisms BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

Fall 2011

Three Domain System of Classification

Fungi in the Tree of Life (cont.) •  Domains - rRNA sequence differences correlate with differences in cellular structure and physiology –  Bacteria - “true bacteria” –  Archaea - “ancient prokaryotes” –  Eucarya - eukaryotes

•  Taxonomic grouping of “Kingdom” lies beneath that of “Domain”

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in the Tree of Life (cont.)

Fungi in the Tree of Life (cont.)

•  Though the fossil evidence suggests fungi were present on earth about 450 million years ago, aquatic fungi (Phylum Chytridiomycota) most likely were present about a million years before this time •  About 354 - 417 million years ago, fungi evolved with primitive land plants

•  These plant-associated fungi probably helped their photosynthetic partners gather nutrients from the harsh soils of the time •  These fungi were the early ancestors of the present day phylum Glomeromycota •  Despite plant-fungus co-evolution, fungi are more closely related to animals

BIOL 6949 (Spring 2011)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Defining the Fungal Kingdom •  Mycology is the study of fungi –  Myco- = fungi –  -ology = the study of

•  Mycology originally arose as a branch of botany because fungi were once believed to be “achlorophyllic” plants

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

Copyright © 2011 Chester R. Cooper, Jr.

Why Study the Fungi? •  There are over 100,000 species of known fungi and probably 15 times that many that have yet to be discovered •  Fungi are an extremely important part of the ecosystem –  Recycling of minerals and carbon –  Source of food, medicines, and chemicals –  Important models in scientific research –  Cause plant and animal diseases BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

Defining the Fungal Kingdom •  Fungi are simple, eukaryotic microbes –  Many are microscopic –  Studies typically employ standard microbiological techniques

Macroscopic (above; from Kendrick, 2003) and microscopic (below; from Cooper) fungi

Fall 2011

Defining the Fungal Kingdom (cont.) •  Mycologists (fungal biologists) have traditionally studied not only the true fungi (e.g., mildew), but also fungus-like organisms (e.g., slime molds) Physarum polycephalum, a slime mold, growing out of Petri dishes (upper image) and a closer view of the plasmodium phase (lower image) Source: waynesword.palomar.edu/slime1.htm

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Defining the Fungal Kingdom (cont.) •  The kingdom Mycota is comprised of the true fungi •  True fungi have the following features:

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Defining the Fungal Kingdom (cont.) •  Fungal features (cont.): –  Typically grow as filaments, termed hyphae (sing., hypha) via apical growth [the latter differs from the growth of other filamentous organisms]

–  Eukaryotic Transmission electron micrograph of a fungal cell showing typical eukaryotic structures. Source: www.stchas.edu/faculty/zfitzgerald/fungi.jpg

Scanning electron micrograph of a fungal hyphae growing on the surface of a leaf. Source: www.abdn.ac.uk/ims/h-em/images/sem4/pages/fungal-hyphae-on-leaf.html

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Defining the Fungal Kingdom (cont.)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Defining the Fungal Kingdom (cont.) •  Fungal features (cont.): –  Fungal hyphae repeatedly branch to form a network of filaments termed a mycelium (sing., mycelia)

Apical growth of a fungal hypha of Sclerotinia sclerotiorum. Source: Fungal Cell Biology Group (www.fungalcell.org)

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

Drawing of a mycelium. Source: www8.nos.noaa.gov/ coris_glossary/index.aspx?letter=m

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

Defining the Fungal Kingdom (cont.)

Fall 2011

Defining the Fungal Kingdom (cont.) •  Fungal features (cont.):

•  Fungal features (cont.):

–  Some fungi can switch growth forms between a hyphal phase and a yeast phase, a property known as dimorphism •  Typically induced by environmental conditions •  A number of such fungi are diseasecausing agents of humans and animals

–  Some fungi grow as a single-celled entity, termed a yeast, that grows either by a budding process or via binary fission

Budding yeast (left) and fission yeast (left). Sources: www.biochem.wisc.edu/yeastclub and www.steve.gb.com/science/model_organisms.html

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Dimorphism of Candida albicans. Source: www.explorepub.com/articles/darkfield_charts/fungus9.html

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Defining the Fungal Kingdom (cont.)

Defining the Fungal Kingdom (cont.)

•  Fungal features (cont.):

•  Fungal features (cont.):

–  Heterotrophic (chemo-organotrophs) - require preformed organic compounds –  Absorb nutrients after degradation by exogenously released enzymes

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Defining the Fungal Kingdom (cont.)

–  Unique cell wall components •  Chitin •  Glucans •  Rare instances of cellulose, but definitely fungal cell walls are not as rich in this polymer as are plants

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Defining the Fungal Kingdom (cont.)

•  Fungal features (cont.): –  Typically have haploid nuclei •  Hyphae often have a number of haploid nuclei present in each cell •  Some yeasts have a single diploid nucleus –  Reproduce both sexually and asexually, typically through the production of spores Asexual mitotically-derived spores (conidia; orange arrow in above figure) of the fungus Scedosporium apiospermum and the meiotically-derived spores (ascospores within a specialized structure termed a cleistothecium; white arrow in figure to the right) of the sexual form of the same organism given the designation Pseudallescheria boydii

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

Defining the Fungal Kingdom (cont.) •  Fungal features (cont.):

Copyright © 2011 Chester R. Cooper, Jr.

Major Activities of Fungi (cont.) •  Plant symbionts

–  Irish potato blight of the 1840s –  Dutch elm disease –  Disappearance of frogs in Costa Rica Phytophthora infestans growing into the leaf of a potato plant (above) and the resulting rotting tuber from infection by this fungus (right). Sources: www.seedquest.com/News/releases/2005/may/12297.htm and www.science.siu.edu/plant-biology/PLB117/JPEG%20files/potato.blight.jpg

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Major Activities of Fungi (cont.) •  Human pathogens

–  Lichens (can also form with cyanobacteria) –  Mycorrhiza

Mycorhizzal fungus associated with roots of a pine. Source: www.virtualmuseum.ca/Exhibitions/Mushroom/English/Species/mycorrhizal.html

BIOL 6949 (Spring 2011)

Major Activities of Fungi •  Plant parasites

–  Other differences between fungi and animals and plants include: •  Histone types •  Sensitivity of microtubules to inhibitors •  Manner of lysine biosynthesis •  Membrane sterols •  Organellar structure/morphology

BIOL 6949 (Spring 2011)

Fall 2011

Copyright © 2011 Chester R. Cooper, Jr.

Major Activities of Fungi (cont.)

–  About 200 known species of fungi are known to infect humans –  Diverse diseases including: •  Dandruff •  “ring worm” •  Pneumocystis infection of HIV-infected persons •  Candidiasis (mucocutaneous and systemic)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Major Activities of Fungi (cont.) •  Decomposition

•  Biological control agents

–  Cellulose (plant material) –  Rumen fungi in cows –  Dry rot

–  Mycoparasites (other fungi) –  Entomopathogens (insects) –  Nematophagous (nematodes)

Dry rot due to the fungus Serpula lacrymans. Source: www.grzyby.pl/gatunki/Serpula_lacrymans.htm

Nematode trapping fungus. Source: Kendrick

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

Major Activities of Fungi (cont.) •  Toxin production (mycotoxins) –  Aflatoxins (peanuts and grains) –  Mushroom poisoning

Fall 2011

Fungi in Biotechnology •  Foods and flavorings –  Edible mushrooms •  5 million tons produced worth $14 billion (1994) •  Diverse types now widely available in supermarkets –  Alcoholic beverages –  Breads, cheeses, soy sauce –  Quorn mycoprotein

Moldy corn due to the aflatoxin producer Aspergillus flavus. Source: www.ipm.iastate.edu/ipm/icm/2001/10-22-2001/earrot.html BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in Biotechnology (cont.) •  Fungal metabolites

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in Biotechnology (cont.) •  Fungal metabolites (cont.)

Lecture: What are Fungi?

Fungi in Biotechnology (cont.) –  Examples of primary metabolites •  Citric acid (estimated 200,000 tons produced in the year 2000) [soft drinks] •  Gluconic acid (estimated annual production of 100,000 tons) [food additive] •  Itaconic acid (estimated annual production of 80,000 tons) [paint and adhesive manufacture]

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in Biotechnology (cont.) •  Enzymes and enzymic conversions

–  Examples of secondary metabolites •  β-lactam antibiotics, e.g., penicillins and cephalosporins •  Non-β-lactam antibiotics, e.g., griseofulvin, gliotoxin, ciclosporins •  Pullulan - film-wrap for food in Japan •  Chitosan - sewage clarification, plant defense initiator BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

•  Fungal metabolites (cont.)

–  Two categories •  Primary - intermediates or end products of common metabolic pathways essential for normal cellular function •  Secondary - diverse range of compounds formed by specific pathways of a given organism and not essential for growth (but may provide some selection advantage)

BIOL 6949 (Spring 2011)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

–  Extracellular enzymes –  Commercially valuable roles •  Food industry •  Bioconversions

•  Heterologous gene products - expression of foreign proteins by fungi having medical/ industrial applications

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

Terms You Should Understand

Fall 2011

Special Lecture Notes on Fungal Taxonomy

•  ‘Fungus’ (pl., fungi) is a taxonomic term and does not refer to morphology •  ‘Mold’ (sometimes spelled ‘mould’) is a morphological term referring to a filamentous (multicellular) condition •  ‘Mildew’ is a term that refers to a particular type of mold •  ‘Yeast’ is a morphological term referring to a unicellular condition

•  Fungal taxonomy is constantly in flux •  Not one taxonomic scheme will be agreed upon by all mycologists •  Classical fungal taxonomy was based primarily upon morphological features •  Contemporary fungal taxonomy is based upon phylogenetic relationships

BIOL 6949 (Spring 2011)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in a Broad Sense

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in a Broad Sense (cont.)

•  Mycologists have traditionally studied a diverse number of organisms, many not true fungi, but fungal-like in their appearance, physiology, or life style •  At one point, these fungal-like microbes included the Actinomycetes, due to their filamentous growth patterns, but today are known as Gram-positive bacteria

•  The types of organisms mycologists have traditionally studied are now divided based upon phylogenetic relationships •  These relationships are:

BIOL 6949 (Spring 2011)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in a Broad Sense (cont.) •  Kingdom Straminipila (Chromista) –  Phylum: Oomycota –  Phylum: Hyphochytridiomycota –  Phylum: Labyrinthulomycota

•  Kingdom Mycetozoa –  Phylum: Myxomycota –  Phylum: Dictyosteliomycota –  Phylum: Acrasiomycota –  Phylum: Plasmodiophoromycota

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

–  Kingdom Fungi - true fungi –  Kingdom Straminipila - “water molds” –  Kingdom Mycetozoa - “slime molds”

Copyright © 2011 Chester R. Cooper, Jr.

Fungi in a Broad Sense (cont.) •  Kingdom Fungi (Mycota) –  Phylum: Chytridiomycota –  Phylum: Zygomycota –  Phylum: Glomeromycota –  Phylum: Ascomycota –  Phylum: Basidiomycota –  Form-Phylum: Deuteromycota (Fungi Imperfecti)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

Fungi in a Broad Sense (cont.) •  Currently accepted scheme is based upon the analyses of Hibbett et al. (2007) –  Kingdom Fungi – Phylum Chytridiomycota – Phylum Neocallismastigomycota – Phylum Blastocladiomycota – Phylum Microsporidia – Phylum Glomeromycota •  Subkingdom Dikarya – Phylum Ascomycota – Phylum Basidiomycota BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Chytridiomycota

Fall 2011

The Mycota (True Fungi) •  Traditionally, differentiated by their mode of sexual reproduction, though not exclusively •  Generally confirmed by phylogenetic analysis •  Kingdom Fungi (Mycota) –  Phylum: Chytridiomycota (motile zoospores) –  Phylum: Zygomycota (zygospores) –  Phylum: Glomeromycota (typically asexual) –  Phylum: Ascomycota (ascospores) –  Phylum: Basidiomycota (basidiospores) –  Form-Phylum: Deuteromycota (Fungi Imperfecti) BIOL 6949 (Spring 2011)

The Chytridiomycota (cont.)

•  ‘Chytrids’ are considered the earliest branch of the true fungi (Eumycota) •  Cell walls contain chitin and glucan •  Only true fungi that produce motile, flagellated zoospores

•  Zoospore ultrastructure is taxonomically important within this phylum

–  Usually single, posterior whiplash type –  Some rumen species have multiple flagella

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Ultrastructure of chytrid zoospores. Source: Kendrick, 2003

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Zygomycota

The Chytridiomycota (cont.) •  Commonly found in soils or aquatic environments, chytrids have a significant role in degrading organics •  A few are obligate intracellular parasites of plants, algae, and small animals (e.g., frogs)

Copyright © 2011 Chester R. Cooper, Jr.

•  Five features of Phylum Zygomycota –  Cell walls contain chitin, chitosan, and polyglucuronic acid –  Some members typically bear multinucleate, coenocytic hyphae, i.e., without cross walls (septa; sing., septum) •  When present, septa are simple partitions •  Some Orders have regular septations that are flared having a centrally plugged pore

Unstained specimen showing a number of oval-shaped chytrids (arrow) infecting the skin of a frog. Source: www.jcu.edu.au/school/phtm/PHTM/frogs/anzcarrt.htm BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

The Zygomycota (cont.)

Fall 2011

The Zygomycota (cont.) –  Produce zygospores (meiospore) via sexual reproduction (gametangial fusion) –  Asexual spores (mitospores), termed sporangiospores, form through cytoplasmic cleavage within a sac-like structure termed a sporangium –  Haploid genome

Diagrammatic comparison of a coenocytic hypha (arrow) with a septated form [left figure] and a photomicroscopic image of coenocytic hyphae from a zygomycetous fungus [right figure]. Sources: www.apsnet.org/education/IllustratedGlossary/PhotosA-D/coenocytic.htm and www-micro.msb.le.ac.uk/MBChB/6a.htm

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Zygomycota (cont.) •  Importance of the zygomycetous fungi –  Organic degraders/recyclers –  Useful in foodstuffs/fermentations –  Pathogens of insects/other animals

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Zygomycota (cont.) •  Generalized life cycle –  Asexual stage (anamorphic; imperfect) •  Hyphae develop erect branches termed sporangiophores Development of erect sporangiophores. Source: Kendrick, 2003

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Zygomycota (cont.) –  Asexual stage (cont.) •  A thin-walled sac (sporangium) is walled off at the tip and fills with cytoplasm containing multiple nuclei (with collumella underneath sac)

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Mature sporangia (left image) and a visible collumella (right image). Source: Kendrick, 2003

Copyright © 2011 Chester R. Cooper, Jr.

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Zygomycota (cont.) –  Asexual stage (cont.) •  Cytoplasmic cleavage and separation of nuclei into walled units produces sporangiospores •  Thin sporangial wall (peridium) breaks releasing sporangiospores

BIOL 6949 (Spring 2011)

Ruptured peridium and underlying sporangiospores (left image) and remaining collumella following complete spore dispersal (right image). Source: Kendrick, 2003

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

The Zygomycota (cont.) –  Asexual stage (cont.) •  Cytoplasmic cleavage and separation of nuclei into walled units produces sporangiospores •  Thin sporangial wall (peridium) breaks releasing sporangiospores

BIOL 6949 (Spring 2011)

The Zygomycota (cont.) –  Asexual stage (cont.) •  Sporangiospores germinate to repeat the asexual life cycle

Diagrammatic representation of sporangiospore development and release. Source: www.unex.es/ botanica/LHB/anima/mucor2.htm

Copyright © 2011 Chester R. Cooper, Jr.

The Zygomycota (cont.) •  The zygospore represents the teleomorphic phase (sexual; perfect form) of this phylum

Mating of Phycomyces in culture (left image) forming a line of darklypigmented zygospores at the point of contact. The zygospores are highly ornate (left image). Source: Kendrick, 2003

BIOL 6949 (Spring 2011)

Fall 2011

Copyright © 2011 Chester R. Cooper, Jr.

Generalized life cycle of a zygomycetous fungus. Source: Deacon, 2006

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Zygomycota (cont.) •  The zygospore represents the teleomorphic phase (sexual; perfect form) of this phylum –  Results from the fusion of gametangia of heterothallic (two different mating types; designated “+” and “-”) or homothallic (self fertile) strains –  Acts as a thick-walled resting spore

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Zygomycota (cont.) Generalized life cycle of a zygomycetous fungus. Source: Deacon, 2006

Diagrammatic representation of zygospore development. Source: www.unex.es/botanica/LHB/anima/mucor3.htm

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

•  Zygosporangium becomes thick walled to form the zygospore •  Hyphae to the sides become empty appendages (suspensor cells) •  Zygospore often forms ornate appendages •  Zygospore is constitutively dormant for a time, but then germinates to produce a sporangium containing haploid sporangiospores BIOL 6949 (Spring 2011)

Zygospore and suspensor cells of Rhizopus. Source: Deacon, 2006

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

The Glomeromycota •  These fungi were originally placed within the Phlyum Zygomycota –  Do not produce zygospores –  Live as obligate, mutualisitic symbionts in >90% of all higher plants - known at arbusular mycorrhizas (AM; endomycorrrhiza)

Fall 2011

The Glomeromycota (cont.) •  Produce large, thick-walled spores in soils that germinate in the presence of a plant root

•  Will not grow axenically Spores of the endomycorrhizal fungus Glomus (top image) and an intracellular endomycorrhizal fungus that has developed vesicles (V) and arbuscules (A) (bottom image). Sources: Kendrick, 2003 and Deacon, 2006

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Glomeromycota (cont.)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Glomeromycota (cont.)

•  Develop non-septate hyphae that invade the root, then form a branch, tree-like arbuscules within the root •  Help plants thrive in nutrient poor soils, especially phosphorous Fossil hyphae and spores (A and B) compared with a spore (C) of a present-day Glomus species (an arbuscular mycorrhizal fungus). Sources: Deacon, 2006

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Ascomycota •  This phylum contains 75% of all fungi described to date •  Most diverse phylum being significant: –  Decomposers –  Agricultural pests (e.g., Dutch elm disease, powdery mildews of crops) –  Pathogens of humans and animals

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Ascomycota (cont.) •  Asexual spores (mitospores) –  Variety of types –  Usually not used for taxonomic purposes –  Generally referred to as conidia –  Tend to be haploid and dormant

BIOL 6949 (Spring 2011)

Mitospores (conidia) of Penicillium. Source: Kendrick, 2003

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

The Ascomycota (cont.) •  Key feature is the ascus (pl., asci) - sexual reproductive cell containing meiotic products termed ascospores

Fall 2011

The Ascomycota (cont.) •  Another significant structural feature - a simple septum with a central pore surrounded by Woronin bodies

Asci and ascospores of Tuber (left image) and Sordaria (right image). Note the thin sac layers (blue arrows) and the ring-like structure (red arrow) in the inoperculate ascus. Source: Kendrick, 2003

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Ascomycota (cont.)

Septate hyphae (left image) and the central pore of a simple septum (right image). Source: Kendrick, 2003

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Ascomycota (cont.) •  The fruiting body of these fungi, termed an ascocarp, takes on diverse forms –  Flasked shaped - perithecium

Perithecium (left image) and asci with ascospores (right image) of Sordaria. Source: Deacon, 2006

These two images show Woronin bodies (WB) and vesicles (V) adjacent to the central pore of a simple septum. Source: www.deemy.de/Descriptors/CharacterDefinition.cfm?CID=366

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Ascomycota (cont.) –  Cup-shaped - apothecium

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

The Ascomycota (cont.) –  Closed structure - cleistothecium

Diagram of an apothecium showing asci/ascospores (left image) and ascomata (apothecia) of Ascobolus (right image). Source: Kendrick, 2003

BIOL 6949 (Spring 2011)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Diagram (left image) and a photomicrograph (right image) of a cleistothecium showing asci/ascospores. Source: Kendrick, 2003

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

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BIOL 6949: Cellular and Molecular Mycology

Fall 2011

The Ascomycota (cont.) –  Embedded structure - pseudothecium –  Some ascospores are borne singly or not enclosed in a fruiting structure

Diagram (left image) and a photomicrograph (right image) of a pseudothecium showing asci/ascospores. Source: Kendrick, 2003

The Ascomycota (cont.) •  Some ascomycetous fungi grow as yeasts –  Either budding or fission –  Both types are capable of sexual reproduction under the appropriate conditions Budding yeast (Saccharomyces cerevisiae; left) and fission yeast (Schizosaccharomyces pombe; right) Sources: www.denniskunkel.com and www.umassmed.edu/bmp/faculty/rhind.cfm?start=Figures&

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Basidiomycota

BIOL 6949 (Spring 2011)

The Basidiomycota (cont.)

•  This phylum contains 30,000 different species or about 37% of all true fungi •  Most often recognized as mushrooms and toadstools, as well as other types of fruiting bodies in nature

•  Very important for their ecological and agricultural impact •  Majority are terrestrial, although some can be found in marine or freshwater environments The mushroom Tricholoma. Source: Kendrick, 2003

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Copyright © 2011 Chester R. Cooper, Jr.

The Basidiomycota (cont.)

The mushroom Russula emetica. Source: Kendrick, 2003

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Basidiomycota (cont.) •  Features similar to those of the Ascomycota

•  Oldest confirmed basidiomycete fossil is about 290 millions years old •  Some are molds, some are yeasts, and some are dimorphic

–  Haploid somatic hyphae –  Septate hyphae –  Potential for hyphal anastomosis –  Production of complex fruiting structures –  Presence of a dikaryotic life cycle phase –  Production of a conidial anamorph Mushroom cap in amber. Source: www.uky.edu/AS/Geology/ webdogs/amber/plants/mushroomb.jpg

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

13

BIOL 6949: Cellular and Molecular Mycology

The Basidiomycota (cont.)

Fall 2011

The Basidiomycota (cont.)

•  Key differences –  Cell wall •  Ascomycetes - two layered •  Basidiomycetes - multilayered –  Septa •  Ascomycetes – Hyphal forms - simple with central pore surrounded by Woronin bodies – Yeast forms - simple with micropores •  Basidiomycetes - dolipore septum BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Ascomyceteous septum (left image) showing Woronin bodies (W) and a basidiomycetous dolipore-type septum (right image) depicting the parenthosome. Sources: forages.oregonstate.edu/is/tfis/enmain.cfm?PageID=69 and Kendrick, 2003

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Basidiomycota (cont.) Dolipore septum in the hypha of the basidiomycetous fungus Coprinus psychromorbidus.

–  Basidiomycetes also form a clamp connection at each septum of a dikaryotic hypha

Clamp connection (left image) and the its dolipore-type septum (right image). Sources: www.apsnet.org/education/IllustratedGlossary/PhotosS-V/septum.jpg and Kendrick, 2003

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Basidiomycota (cont.) –  Meiospore production - meiosis occurs within a specialized cell termed a basidium (pl., basidia), but the spores are borne exogenously on tapering outgrowths termed sterigmata (sing., sterigma)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Basidiomycota (cont.) –  Sterigmata form on the surface of the basidium –  Haploid nuclei migrate into the sterigmata as the basidiospore develops Transmission electron micrograph of a basidium with the accompanying sterigma and basidiospores. Source: www.bsu.edu/classes/ruch/msa/mims/1-39.jpg

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

14

BIOL 6949: Cellular and Molecular Mycology

Fall 2011

The Basidiomycota (cont.) Basidiosporogenesis. Source: Kendrick, 2003

–  Mature basidiospore in many fungi released through a ballistic-like method involving a hylar (or hilar) drop

Scanning electron micrograph of a basidium with the accompanying sterigma, basidiospore, and hilar droplet. Source: from McLaughlin et al. (1985) as depicted at tolweb.org/tree?group=Basidiomycota

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Basidiomycota (cont.) –  Mature basidiospore in many fungi released through a ballistic-like method involving a hylar (or hilar) drop

Copyright © 2011 Chester R. Cooper, Jr.

The Mitosporic Fungi (cont.) •  Due to the absence of a teleomorph, these fungi are often given a provisional name termed a “form” genus/species •  If the teleomorph is discovered, the fungus renamed

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

The Mitosporic Fungi •  Many ascomycetous fungi produce asexual (mitotic) spores (anamorphic phase), but their teleomorph phase (sexual reproduction) is absent •  Taxonomically, such fungi are placed in an artificial category variously termed Deuteromycota (or Deuteromycotina) or Fungi Imperfecti

Diagrammatic representation of basidiospore release involving a hilar drop. Source: www.unex.es/botanica/LHB/an/basid0.gif

BIOL 6949 (Spring 2011)

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

The Mitosporic Fungi (cont.) •  Example of teleomorph/ anamorph dichotomy of names: –  Anamorph - Aspergillus nidulans - forms mitosporically-derived conidia, therefore classified within the form-phylum Deuteromycota

BIOL 6949 (Spring 2011)

Scanning electron micrograph of conidia and phialides of Aspergillus nidulans. Source: www.gettysburg.edu/~rcavalie/em/sem_pics.html

Copyright © 2011 Chester R. Cooper, Jr.

15

BIOL 6949: Cellular and Molecular Mycology

The Mitosporic Fungi (cont.)

The Mitosporic Fungi (cont.) •  Conidia are produced in a variety of ways, but never by cytoplasmic cleavage as in the Zygomycota •  Two main types of conidium development are the basis for the production for all types of conidia

–  Teleomorph - Emerciella nidulans - forms a cleistothecium containing ascospores, therefore classified within the Phylum Ascomycota

Cleistothecium of Aspergillus. Source: www.angelfire.com/wizard/kimbrough/Textbook/ CommonGroupsZygoAsco_blue.htm

BIOL 6949 (Spring 2011)

Fall 2011

Copyright © 2011 Chester R. Cooper, Jr.

–  Thallic - fragmentation process –  Blastic - swelling process

BIOL 6949 (Spring 2011)

Copyright © 2011 Chester R. Cooper, Jr.

Thallic vs. Blastic

Geotrichum candidum. Source: www.doctorfungus.com

Phialophora verrucosa. Source: pathmicro.med.sc.edu/mycology/ mycology-5.htm

Thallic vs. blastic conidiogenesis. Source: Kendrick, 2003

BIOL 6949 (Spring 2011)

Lecture: What are Fungi?

Copyright © 2011 Chester R. Cooper, Jr.

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