Lecture on Fungi

11/25/13 Monday

Characteristics

• nonphotosynthetic• Most are saprobes (feed on dead things)• Cell wall made of chitin• Genetically more similar to animals

Importance

• Decomposer and recycler of nutrients• Consumed as food and food production• Truffles, morels, mushroom • Antibiotic: penicillin

Antibiotics

• Cyclosporin prevent organ rejection• Statin lowers cholesterol• Penicillin

Mutual symbionts of pants

• Mycorrhizae• lichens

lichen

• Mutual symbiont of algae• Indicator of air pollution• Source of dyes (litmus)

Three forms of lichen (Know for lab exam)

1. Crustose: crustlike, growing tight against the substrate.

2. Foliose: leaflike, with flat sheets of tissue not tightly bound

3. Fruticose: free-standing branching tubes.

Mycoses

• Agents of disease

Four Fungal diseases

1. Thrush: yeast infection2. Histoplasmosis : lung infection3. Aspergillosis : mold in your house4. Cryptococcus /Valley fever: can lead to

pneumonia and meningitis

ergotism

• Clavicles fungus• Salem witch trials

Sporotrichosis: rose gardener’s disease

• Fungal antibiotics are harmful; humans and fungi are eukaryotes. Bacterial infections are better to treat because they are prokaryotes

Tinea Infections (Ringworm)

• Infection on skin and nail’s keratin

Claviceps purpurea, cause of ergotism

Plant diseases caused by fungi

1. Rust2. Apple Scab 3. smut

cellular

• Unicellular (yeast)• Multicellular (mold)

• Some are yeast inside and mold outside the body

Structure

• Mycelia: networks of branched hyphae (cells)• Septum (cell wall) separating the hyphae• Coenocyte fungi lack septa and cellular

contents can flow between the hyphae

Septate hyphae

• Septum: a cross-wall formed in association with the mitotic division of a cell, laid down between the cells, usually at regular intervals.

Coenocytic hyphae

• multinucleate mass of protoplasm resulting from repeated nuclear division unaccompanied by cell fission

Types of mycorrhizae fungi

• Ecto : grow into the extracellular species of the root cortex (truffle)

• Endo: grow into the root cell (orchid)

Reproduction

• Plasmogamy: union of two parent mycelia• Heterokaryon: cell or mycelium in some fungi

that do not result in the fusion of two nuclei• Dikaryotic: the nucleus pair off two to a cell

Karyogamy (nuclear fusion)

• Produce diploid cells• Takes a long time• 2n phase is short-lived and undergo meiosis,

producing 1n spores

sporangium

• Fungal structures where asexual spores are produced

• exam

budding

• Simple cell division in which yeast repouce asexually

Imperfect fungi/deuteromycetes

• Some fungi have no known sexual stage

Evolution

• Fungi descended from protists• Fungi and Animalia are sister kingdoms

Groups you must know

1. Chytridiomycota: earliest fungi2. Zygomycota3. Glomeromycota4. Ascomycota5. Basidiomycota

Chytridiomycota: earliest fungi

• Found in water• Saprobic or parasitic• B. dendrobatids: decline of frog population• Chytrids diverged earliest

Zoospores: flagellated spores

• Only chytrids have zoospores

Zygomycota

• Asexual and sexual spores• Zagospore (sexual)• Sponragiospores (asexual spores) • Very cold/heat tolerant, responsible for food

spoilage• Black bread mold Rhizopustoloniser• pilobolus

Life cycle

• Zygomycota

glomeromycota

• Arbuscular mycorrhizae: endo• 80% of all vascular plants have arbuscular

mycorrhize• Reproduce asexually• Help plants absorb phosphorous and help a

crucial role in colonization of land by plants

Ascomycetes (cup fungi)

• Asci: sexual spores that are found in saclike structure

• Reproduce sexually• Many asci are found on the fruiting body

called ascocarp• Ex. Truffle• Conodia: asexual spores• Conodiophore: structure

Penicillium conidiophores

Sporangium conidiophore

Aspergillus condiophore

Ascomycetes

• Truffles, yeast, penicillin, morels

Ascomycetes

• Fungal partner in lichen is an ascomycete

Basidiomycetes: typical mushroom

• Basidium: structure where sexual spores (basidiospores) are produced

• Gills with basidia

Reproduction of Basidiomycetes: typical mushroom

• Sexual mostly resulting in dikaryotic fruiting bodies called basidiocarps (mushroom)

• Karygomy occurs in the gills of the mushroom cap where basidium and basidiophores are found

• Asexual reproduction is rare and occur via fragmentation

• Ex. Club fungi, rust, smut, puff balls, shelf fungi, mushrooms

Basidiomycete life cycle• Basidiomycetes – Fungi• Key Points• The basidiomycetes (phylum Basidiomycota) are comprised of roughly

30,000 species that include mushrooms, shelf fungi and puffballs.• The basidium is a specific, club-shaped cell where karyogmay is carried

out followed by meiosis. This gives rise to the name club fungus.• A diploid nucleus is formed during karyogamy and then undergoes

meiosis, resulting in four haploid nuclei. The basidium divides into four arms, with a single haploid nucleus in each that will develop into a basidiospore.

• The reproductive cycle of basidiomycetes has a long dikaryotic mycelium stage allowing for genetic diversity as a result of recombination.

• Basidiomycetes are particularly important in nature as decomposers of plant material, especially dead wood and trees.

• Terms• basidium

a small structure, shaped like a club, found in the Basidiomycota phylum of fungi, that bears four spores at the tips of small projections

• Karyogamy The fusion of two nuclei within a cell.

• Mycelium The vegetative part of any fungus, consisting of a mass of branching, threadlike hyphae, often underground.

• mycelium the vegetative part of any fungus, consisting of a mass of branching, threadlike hyphae, often underground

Glossary

• http://bugs.bio.usyd.edu.au/learning/resources/Mycology/Glossary/glossary_a_b.shtml