A fungus is not a plant. Fungus Animal Plant Chitin yes yes no Food storage glycogen glycogen starch Multicellular fungi consist of mycelium, which are made up of strands called hyphae. Hyphae have enormous surface areas. Absorbs food from environment. Prone to drying out. Most of “body” of fungus is feeding structure. Only reproductive body typically exposed to air. Thick, fleshy structure of “shroom” prevents drying out. Reproductive structure produces spores Ascomycetes have spores in sacs. Basidiomycetes have spores on clubs. In fungi, cytoplasm of two individuals fuses, but their nuclei may remain separate for a long time. Fungal phylogeny is a work in progress! No point in learning this now, will change. Importance of Fungi: 1. Decomposers 2. Mycorrhizae 3. Lichens 4. Economic Impacts Fungi as decomposers Basidiomycete fungi are the only organisms that can completely digest the lignin in wood. Fungi serve an essential role in the carbon cycle. Adaptations helping with decomposition: 1. Extracellular digestion Only small molecules can cross plasma membranes. Secreted enzymes break down large molecules. Adaptations helping with decomposition: 2. Lignin peroxidase Enzyme catalyzes removal of a single electron; creating a highly reactive atom. “Enzymatic combustion” Uncontrolled oxidation reaction breaks up polymer. (Most enzymatic reactions very specific, but lignin itself highly random). Randomness of reaction means that E from oxidation can’t be harnessed. Adaptations helping with decomposition: 3. Cellulose digestion By cutting up lignin, fungi gain access to cellulose. The cellulase enzymes digest cellulose into glucose, which can be used for food. Importance of Fungi: 1. Decomposers 2. Mycorrhizae 3. Lichens 4. Economic Impacts Fungi as partners with plants: Mycorrhizae Importance of mycorrhizae discovered in ‘70’s. Failure of pine plantations key observation. Fungi as partners with plants: Mycorrhizae EM fungi on most trees in temperate & boreal forests. Hyphae penetrate dead leaves, twigs. Release enzymes that cleave peptide bonds. Provide N to plant in exchange for C. Fungi as partners with plants: Mycorrhizae AMF important in tropics and grasslands, on 80% of plants. Ancient; fossil from 400 mya. Provide phosphorus to plant in exchange for C. Importance of Fungi: 1. Decomposers 2. Mycorrhizae 3. Lichens 4. Economic Impacts Fungi as colonizers: lichens Lichens are composed of fungal hyphae and a layer of autotrophic green algae or cyanobacteria Colonize bare rock following glaciation. First stage in soil building. Importance of Fungi: 1. Decomposers 2. Mycorrhizae 3. Lichens 4. Economic Impacts Of course, the most important economic impacts are those already mentioned. Fungi rot crops. A fungus called ergot is associated with accusations of witchcraft. Ergot poisoning causes convulsions, shaking, or spasms and sometimes hallucinations or gangrene. Ergot is the original source from which LSD first isolated. http://www.botany.hawaii.edu/faculty/wong/BOT135/LECT12.HTM Fungi are thought to contribute to the worldwide decline of amphibian populations. A fungus has caused the virtual extinction of the American chestnut. Note the man, to show scale. The first antibiotic was derived from Penicillium. This is also the genus used to make blue cheeses. Penicillium roquefortii is used in the manufacture of blue cheeses e.g. Roquefort, Gorgonzola, Stilton, etc. During the fermentation process the fungus spores are injected into the curd. By the way, the blue in the blue-cheese is caused by the pigment in the spores of the fungus. So, when you eat blue cheese you are consuming spores by the million. http://www.virtualmuseum.ca/Exhibitions/Mushroom/English/Lives/index.html Yeast is the workhorse of eukaryote genetics. Yeasts are also essential to the production of wine, beer and bread. Some fungi are just really cool.