Today: Review of the “Fungus- like” Protists The REAL Fungi Reminder: Fieldtrip Monday! Wear close- toed shoes. Dress for the weather. Meet at the Administration Building at 1 pm.

The Absorptive Protists: A Closer Look

What do we know about these?? Could you draw a lifecycle??

The Plasmodial Slime Mold Life Cycle

The Dictyostelida- Cellular Slime Molds Feeding stage consists of solitary cells functioning individually Feeding stage consists of solitary cells functioning individually When food is low, cells follow chemical trails to form an aggregate (pseudoplasmodium) When food is low, cells follow chemical trails to form an aggregate (pseudoplasmodium) Cells in the aggregate maintain their membranes Cells in the aggregate maintain their membranes Haploid organisms! Haploid organisms! Most have no flagellated stages Most have no flagellated stages

The Dictyostelida- Cellular Slime Molds

The Oomycotes (Water Molds and Their Relatives)

Oomycota: Water Molds and Their Relatives Includes water molds, white rusts, and downy mildews Includes water molds, white rusts, and downy mildews All are heterotrophic stramenopiles (“straw hair”) All are heterotrophic stramenopiles (“straw hair”) May be unicellular or consist of multi- nucleated hyphae (convergent evolution!!) May be unicellular or consist of multi- nucleated hyphae (convergent evolution!!) Have cell walls made of cellulose Have cell walls made of cellulose Most are diploid dominant (unlike true fungi!) Most are diploid dominant (unlike true fungi!) Have biflagellated cells during their life cycle Have biflagellated cells during their life cycle

White Rusts Generally parasites of terrestrial plants Flagellated zoospores infect and feed on plant tissues white pine blister rustwhite pine blister rust is the pale to orange colored blisters formed on white pine stem after infection chrysanthemum with CWR

Arabidopsis thaliana - Peronospora parasitica. P. parasitica is a downy mildew pathogen belonging to the oomycetes Downy Mildews Also typically parasites of terrestrial plants Downey mildew on soybeans

Other Famous Oomycetes Potato blight (caused Irish Famine- late 1840’s) Potato blight (caused Irish Famine- late 1840’s)

The Water Molds Important decomposers and parasites in aquatic systems Important decomposers and parasites in aquatic systems secondary Saprolegnia infection

Next: Thinking About Real Fungi

General Characteristics

Mostly multicellular eukaryotes Mostly multicellular eukaryotes More closely related to animals than plants! More closely related to animals than plants! Distinguished by their: Distinguished by their: Nutritional Mode Structural Organization GrowthReproduction

Nutritional Mode- Fungi Heterotrophs Heterotrophs Acquire nutrients by absorption Acquire nutrients by absorption External digestion ( exoenzymes ) External digestion ( exoenzymes ) Makes them important decomposers! Makes them important decomposers! Parasitic fungi digest and absorb tissues of host! Parasitic fungi digest and absorb tissues of host!

Fairy Rings WHY?? Could you draw a typical fungal body?? Try to include the following key terms: hyphae, septa, mycellium Could you draw a typical fungal body?? Try to include the following key terms: hyphae, septa, mycellium

Structural Organization- Fungi Vegetative bodies usually diffusely organized within and around the food source Vegetative bodies usually diffusely organized within and around the food source Except yeasts, fungi constructed of filamentous hyphae Except yeasts, fungi constructed of filamentous hyphae Hyphae form an interwoven mat, a mycellium Hyphae form an interwoven mat, a mycellium Largest mycellium discovered is 3.4 miles in diameter!! Largest mycellium discovered is 3.4 miles in diameter!!

The Fungi: Structural Organization

Most hyphae are divided into cells by cross- walls called septa (septa have large pores!) Most hyphae are divided into cells by cross- walls called septa (septa have large pores!) Some fungi are aseptate - no divisions within the hyphae. These are the Coenocytic Fungi Some fungi are aseptate - no divisions within the hyphae. These are the Coenocytic Fungi Parasitic fungi have modified hyphae, haustoria, specialized to penetrate the tissues of the host Parasitic fungi have modified hyphae, haustoria, specialized to penetrate the tissues of the host Most fungal cell walls are composed of chitin Most fungal cell walls are composed of chitin Structural Organization- Fungi

Fungal Growth Growth is extremely rapid! (can add 1 kilometer per day of hyphae!!) Growth is extremely rapid! (can add 1 kilometer per day of hyphae!!) Possible because of efficient transfer of materials by cytoplasmic streaming to the tips Possible because of efficient transfer of materials by cytoplasmic streaming to the tips

Fungal Dispersal and Reproduction Fungi reproduce by releasing spores Fungi reproduce by releasing spores Spores may be produced either sexually or asexually Spores may be produced either sexually or asexually A single fungus may produce trillions of spores A single fungus may produce trillions of spores

Fungal Life Cycles Most fungal hyphae and spores are haploid Most fungal hyphae and spores are haploid Some mycelia may form through the fusion of two genetically distinct hyphae. This mycelium is then a heterokaryon. Some mycelia may form through the fusion of two genetically distinct hyphae. This mycelium is then a heterokaryon. The distinct nuclei may remain isolated, or may mingle and even exchange chromosomes and genes via a cross-over like process. The distinct nuclei may remain isolated, or may mingle and even exchange chromosomes and genes via a cross-over like process.

Sexual Reproduction in Fungi Sexual Reproduction in Fungi In sexually reproducing fungi, the union occurs in two stages: In sexually reproducing fungi, the union occurs in two stages: 1. Plasmogamy- fusion of the parents’ cytoplasm 2. Karyogamy- fusion of haploid nuclei of the two parents During the time lag (minutes to centuries!) the mycelium is a heterokaryon During the time lag (minutes to centuries!) the mycelium is a heterokaryon Occasionally the haploid nuclei pair off, two to a cell. This mycelium is dikaryotic. Occasionally the haploid nuclei pair off, two to a cell. This mycelium is dikaryotic.

Sexual Reproduction in Fungi Sexual Reproduction in Fungi You Try!

Fungal Evolution Animals and fungi from a common aquatic, flagellated, protistan ancestor?

Evolution of the Fungi

The Chytridiomycota Mainly aquatic Mainly aquatic May be saprobes, parasites May be saprobes, parasites Form flagellated spores (zoospores)  Protists?? Form flagellated spores (zoospores)  Protists?? Most have coenocytic hyphae, some unicellular Most have coenocytic hyphae, some unicellular

Chytrids and Fungal Evolution Chytrids are found associated with plants very early in the fossil record ( Chytrids are found associated with plants very early in the fossil record ( million years ago) Molecular evidence also suggests these are the most primitive fungi Molecular evidence also suggests these are the most primitive fungi

The Zygomycota- the Zygote Fungi Mostly terrestrial in soil or on decaying material Mostly terrestrial in soil or on decaying material Distinguished by a resistant zygosporangium Distinguished by a resistant zygosporangium Hyphae are coenocytic with septa only where reproductive cells are formed Hyphae are coenocytic with septa only where reproductive cells are formed

You Try: Modify your generic fungal lifecycle to represent a zygomycete. Zygomycete Life Cycle

Famous Zygomycota The black bread mold, Rhizopus The black bread mold, Rhizopus The dung fungus, Pilobolus The dung fungus, Pilobolus

The Glomero- mycetes Small but ecologically distinct group! Small but ecologically distinct group! Form arbuscular mychorrhizae Form arbuscular mychorrhizae Photo: Ryan Geil

Evolution of the Fungi

The Ascomycota (Sac Fungi) 30,000+ species from marine, freshwater, and terrestrial habitats 30,000+ species from marine, freshwater, and terrestrial habitats Unicellular yeasts to large elaborate morels! Unicellular yeasts to large elaborate morels! Many live with algae as lichens, may also form mycorrhizae with plants, or between cells in leaves! Many live with algae as lichens, may also form mycorrhizae with plants, or between cells in leaves!

You Try: Modify your generic fungal lifecycle to represent an Ascomycete. Ascomycetes

Other Ascomycetes

Infamous Ascomycetes… An American Chestnut Tree with Chestnut Blight

The Basidiomycota- Club Fungi ~30,000 fungi including mushrooms, shelf fungi, puffballs, and rusts & smuts ~30,000 fungi including mushrooms, shelf fungi, puffballs, and rusts & smuts Important decomposers (lignin!), also form mycorrhiza Important decomposers (lignin!), also form mycorrhiza

You Try: Modify your generic fungal lifecycle to represent a Basidiomycete.

Other Basidiomycetes

Wood Rot Brown Wood Rot: Fungi eats cellulose and leaves behind brown lignin Brown Wood Rot: Fungi eats cellulose and leaves behind brown lignin White Wood Rot: Fungi eats brown lignin and leaves behind white cellulose White Wood Rot: Fungi eats brown lignin and leaves behind white cellulose Very important to nutrient cycling!! Very important to nutrient cycling!! Images: Tom Volks, University of Wisconsin

Evolutionarily, the Fungi are Divided into Phyla based on Reproductive Strategy

Ecological Adaptations in the Fungi 1. Molds- Rapidly growing, asexually reproducing fungus Rapidly growing, asexually reproducing fungus Grow as saprobes or parasites on a variety of substrates Grow as saprobes or parasites on a variety of substrates Example: Penicillium (an ascomycete) Example: Penicillium (an ascomycete) Molds that have no known sexual stage are called imperfect fungi (deuteromycetes)

2. Yeasts- Unicellular fungi in moist of liquid habitats Unicellular fungi in moist of liquid habitats Reproduce asexually by simple division or budding Reproduce asexually by simple division or budding Includes members of the Ascomycota, Basidiomycota and Imperfect Fungi. Includes members of the Ascomycota, Basidiomycota and Imperfect Fungi. Ecological Adaptations in the Fungi

3. Lichens- Symbiotic association of millions of algae or cyanobacteria within a mesh of fungal hyphae (most commonly ascomycetes) Ecological Adaptations in the Fungi

3. Lichens- Lichens absorb most of their minerals from dust or rain, making them good colonizers, but sensitive to pollutants. Lichens survive in very arid conditions, but photosynthesize only when water levels are sufficient, resulting in extremely slow growth. Ecological Adaptations in the Fungi

4. Mycorrhizae- Mutualistic associations of plant roots and fungi Mutualistic associations of plant roots and fungi Increase the absorptive surface of the plant roots Increase the absorptive surface of the plant roots Fungus provides minerals for organic nutrients synthesized by the plant Fungus provides minerals for organic nutrients synthesized by the plant Found in almost all vascular plants! Found in almost all vascular plants! Ecological Adaptations in the Fungi

4. Mycorrhizae- Can be endo or ecto- mycorrhizae Endo mycorrhizae- penetrates the cortical cells (but not the cell membrane); usually a zygomycete (Arbuscular Mycorrhizal Fungi) Ecto mycorrhizae- forms a sheath around the root; usually a basidiomycete Ecological Adaptations in the Fungi

Ectomycorrhizae Ectomycorrhizae occur in almost all tree species in temperate and boreal forests. Short growing seasons in these areas limit decomposition and create nitrogen stress. The fungi release peptidases (exoenzymes) that break down proteins, releasing N-containing compounds.

Endomycorrhizae Endomycorrhizae are found in ~80% of all plants, especially in warm/tropical grasslands and forests. They help supply phosphorus to the plants.

Most vascular plants are associated with mycorrhizae. Photo: Barley grown with (right) and without (left) mycorrhizae.

An Unusual Niche: Indian Pipe This plant does not photosynthesize!

Other Interesting Fungi Some produce antibiotics, like penicillin! Discovered, accidentally, in 1928 (from Penicillium notatum) Discovered, accidentally, in 1928 (from Penicillium notatum) Tested in humans 1941 Tested in humans 1941 Nobel prize, (Fleming, Florey, and Chain) Nobel prize, (Fleming, Florey, and Chain) Photo: Alexander Fleming's photo of the dish with bacteria and Penicillin mold

Other Interesting Fungi Food Production SEM; Saccharomyces cerevisiae

Other Interesting Fungi Aflatoxins First identified from Aspergillus flavus when turkeys fed moldy peanut meal fell ill First identified from Aspergillus flavus when turkeys fed moldy peanut meal fell ill Many other mycotoxins now identified! Many other mycotoxins now identified! Aflatoxins appear to cause stunted growth, liver problems and immune system suppresion, especially in children Photo: AgriForum

Other Interesting Fungi Fungal Pathogens Above: Tinea dorporis (ring worm) - Acute - Forearm At Right: Top= normal esophagus, Bottom = Esophageal candidiasis

Fungal hyphae growing through a hair from a cat with ringworm.

Other Interesting Fungi Poisonous Mushrooms (Toadstools) Especially Amanita sp. (Death’s cap) Toxin produced inhibits mRNA synthesis! Death Cap ( Amanita phalloides ) Photo: perspective.com

Other Interesting Fungi Hallucinogenic mushrooms Produce two alkaloids, psylocibin and psylocin (structurally similar to serotonin and LSD) Produce two alkaloids, psylocibin and psylocin (structurally similar to serotonin and LSD) Resemble toxic mushrooms!! Resemble toxic mushrooms!! Fly Agaric (Amanita muscaria) Photo: perspective.com

Some Quick Lab Review… What is this? Can you identify key structures?

Some Quick Lab Review… What is this? Can you identify key structures?

Some Quick Lab Review… What is this? Can you identify key structures?

Some Quick Lab Review… What is this? Can you identify key structures?