THE DIVERSITY OF FUNGI by Aditya Murali, Petr Sharetskiy, and Brendan Lo

WARNING The following presentation may contain images and details which some may find disgusting and/or offensive. Viewer discretion is advised.

Division Chytridiomycota There are 100, 000 known species of fungi, and scientists estimate that there may be 1.5 million species worldwide Chytrids are a group of organisms (usually aquatic) that are links between fungi and protists Recent discoveries show similar comparisons between the sequences for proteins, nucleic acids, enzymes, and metabolic pathways in chytrids and fungi. Due to their flagella, Chytrids may be primitive fungi

Division Zygomycota Zygote fungi, or zygomycetes, are mostly terrestrial and live in soil or decaying organic materials One group forms mycorrhizae, or mutualistic associations with the roots of plants

Division Zygomycota An example of a zygomycete is the black bread mold In the asexual phase, sporangia, each containing hundreds of spores, form on hyphae and can spread out over the bread and form new mycelia If the environment deteriorates, mycelia of opposite mating types (with genetically different nuclei) sexually reproduce and form dikaryotic (two, unfused nuclei) zygosporangia, which are active in better environmental conditions

Division Ascomycota Ascomycetes, or sac fungi, live in marine, freshwater, and terrestrial habitats Although some are pathogenic to plants, others form symbiotic relations with algae (called lichens) or form mycorrhizae with plants. Still others protect plants from insects by releasing toxic chemicals Asci are sacks of sexual spores; ascocarps are macroscopic fruiting bodies where most sac fungi bear their sexual stages In asexual reproduction, ascomycetes produce conidia, which are naked spores, on the hyphae Ascomycetes have more extensive dikaryotic stages, mainly in the form of dikaryotic hyphae

Division Basidiomycota The name comes from basidium, a transient diploid stage in the organism’s like cycle. Basidiomycetes are important decomposers of wood and other plant material. Many fungi of group parasitize the wood of weak or damaged tress and decompose the wood after the trees die. Two Groups of basidiomycetes: - Rusts, Smuts Both include particularly destructive plant parasites

Division Basidiocarps Life cycle of a fungi includes a diacritic mycelium. In response to environmental stimuli, this mycelium reproduces sexually by producing fruiting bodies called Basidiocarps. Mushrooms are great examples of basidiocarps. The cap of mushrooms supports and protects a large surface area of basidia on gills and may release up to a billion basisdiospores, which drops beneath the cap and are blown away.

Molds A mold is a rapidly growing, asexually reproducing fungus. The mycelia grow as saprobes or parasites on a great variety of substrates. Example: Ruinous (bread mold) There exist molds that cannot be classified as zygomycetes or basidiomycetes because they have no known sexual stages. These are called imperfect fungi. Imperfect fungi reproduce asexually by producing spores. Some predatory fungi trap, kill, and consume protists and small animals which provides additional nitrogem-containing compounds. There are any extant uses of molds. Act as sources of antibiotics and are utilized in various ways in human immunizing therapy.

Yeasts Yeasts are unicellular fungi that inhabit liquid or moist habitats, including plant sap and animal tissues. Reproduces asexually by simple cell division or by the pinching of small “bud cells” off a parent cell. Humans have used yeasts to raise bread and ferment alcoholic beverages for thousands of years. Some yeasts cause problems for humans.

Lichen A lichen is a symbiotic association of millions of photosynthetic microorganisms held in a mesh of fungal hyphae. The photosynthetic partner is usually an algae or cyanobacteria. Merging of fungus and alga is so complete that lichens are actually given genus and species name as though one organism. Lichens are among the first organisms to enter new habitats free of any life and make it possible for a succession of plants to grow. Resistant to temperature change but their passive mode of mineral uptake makes them susceptible to air pollution.

Ecological Impacts of Fungi Wood-rotting fungi became a dominant group of organisms about 250mya at end of the Permian era. Fungi are necessary to dismantle organic material so that the elements don’t accumulate in dead organic matter. Some fungi are pathogens. Fungi cause diseases like athlete’s foot, vaginal yeast infections, and lung infections that may be fatal. Fungi and animals probably evolved from a common protistan ancestor.

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