2The Characteristics of Fungi Body formunicellularMulti-cellular
3Mycelium – Branched Hyphae fruiting bodiesboth are composed of hyphaeMycelium – Branched Hyphae
4The Characteristics of Fungi Heterotrophic -Saprophytes or saprobes –Symbionts -Parasites –Parasites that cause disease are called pathogens.
5The Characteristics of Fungi Heterotrophic - 'other food'Saprophytes or saprobes - feed on dead tissues or organic waste (decomposers)Symbionts - mutually beneficial relationship between a fungus and another organismParasites - feeding on living tissue of a host. Parasites that cause disease are called pathogens.
6Heterotrophic by Absorption Fungi get carbon from organic sourcesHyphae release enzymesEnzymatic breakdown of substrateProducts diffuse back into hyphaeEnzymatic breakdownMost enzyme release (and absorption) at tipsProteins and other materials synthesized by the entire mycelium are channeled by cytoplasmic streaming to the tips of the extending hyphae.Nucleus hangs backand “directs”ProductsEnzymesProduct diffuses backinto hypha and is used
7Hyphae Tubular Hard wall of chitin Grow at tips Chitin is the same material used by Arthropods (Insects, crabs, etc.) in their exoskeletonsaNuclei of fungi are hard to see without stains
8Hyphal growth Hyphae grow from their tips Mycelium = extensive, feeding web of hyphaeMycelia are the ecologically active bodies of fungiThis wall is rigidOnly the tip wall is plastic and stretches
12Lichens “Mutualism” between Fungus – structure Alga or cyanobacterium – provides foodThallus is a plant-like body that doesn’t have roots, stems or leavesThallus doesn’t look like either partnerDual nature of thalli was not fully understood until early 1900’sFungus gives the name to the lichen (by agreement)Fungus usually, but not always, an Ascomycote (in 8+ independent orders)Algae green. If bluegreen bacteria present, lichens fix nitrogen (turn atmospheric nitrogen into amino acid nitrogen in proteins)
13Lichen internal structure The nature of lichen symbiosis is may also be described as mutual exploitation instead of mutual benefit.Lichens live in environments where neither fungi nor algae could live alone.While the fungi do not not grow alone in the wild, some (but not all) lichen algae occur as free-living organisms.If cultured separately, the fungi do not produce lichen compounds and the algae do not “leak” carbohydrate from their cells.In some lichens, the fungus invades algal cells with haustoria and kills some of them, but not as fast as the algae replenish its numbers by reproduction.Lobaria oregana prefers old-growth conifer canopies in forests with clean air.Lichens are nature’s biological indicators of pollution and air quality.Lobaria
15Fungi are Spore-ific!!!Spores - asexual (product of mitosis) or sexual (product of meiosis) in origin.
16Reproduce by spores Formed: Directly on hyphae Fungi reproduce by releasing spores that are produced either sexually or asexually.The output of spores from one reproductive structure is enormous, with the number reaching into the trillions.Dispersed widely by wind or water, spores germinate to produce mycelia if they land in a moist place where there is food.Penicillium hyphae with conidia
17Hyphal growth from spore germinatingsporeFungal mycelia can be huge, but they usually escape notice because they are subterranean.One giant individual of Armillaria ostoyae in Oregon is 3.4 miles in diameter and covers 2,200 acres of forest,It is at least 2,400 years old, and weighs hundreds of tons.(Actually noone has seen this of this extent – but cultures have been taken from soil over that area and all isolates have been found to be the same individual)Ten cubic centimeters of rich organic soil may have fungal hyphae with a surface area of over 300 cm2myceliumMycelia have a huge surface area
18The Characteristics of Fungi Classified by how they reproduce.100,000 Species (estimated 1.5 million species total).Found everywhereCell wall present, composed of cellulose and/or chitin.Food storage - generally in the form of lipids and glycogen.Eukaryotes - true nucleus and other organelles present.All fungi require water and oxygen.
19Ascomycota – “sac fungi” Sexual Reproduction – asci (sing. = ascus) - SACAsex. Reprod. – commonCup fungi, morels, trufflesImportant plant parasites & saprobesYeast - SaccharomycesDecomposers, pathogens, and found in most lichensMycologists have described over 60,000 species of ascomycetes, or sac fungi.Ascomycota tend to grow from spore to spore in one year and relate well to living plant tissuesThere is diverse form in the growth and fruiting structures – yeasts to morels, many intermediate (and small)Asexual reproduction by conidia (externally produced, not in sporangia)Half of the Ascomycota form lichens (evolved 8 or more times in different orders) but not all lichens are AscomycotesA cluster of asci with spores inside
21Sac fungi diversityThis begins the first of several photographic reviews of fungal diversity. Enjoy the pictures and try and get a feeling of some of the different forms these fungi take and their roles in the environment.
22Basidiomycota – “club fungi” Sexual Reproduction – basidia - CLUBAsexual reprod – not so commonRusts & smuts –plant parasitesMushrooms, puffballsEnzymes decompose wood, leaves, and other organic materialsAsexual spores conidiaEcologically important on wood as decomposers and parasitesHalf the mushrooms form mycorrhizasSEM of basidia and spores
24Deuteromycota – Form Phylum “Imperfect Fungi” Fungi that seldom or never reproduce sexually.Asexual reproduction by vegetative growth and production of asexual spores common.
25Yeasts Single celled fungi Adapted to liquids Plant saps Water films Moist animal tissuesBread and wine yeast, the budding yeast, SaccharomycesEasily cultured. For a time, this was the most important organism for studying the molecular genetics of eukaryotesThus, Saccharomyces is arguably the most important organism known to humansCandida causes diseases of humans, usually experiencing chemical imbalance or immune problemsCandidaSaccharomyces
26Molds Rapidly growth Asexual spores Many human importances Food spoilageFood productsAntibiotics, etc.Noble Rot - BotrytisA mold is a rapidly growing, asexually reproducing fungus.The mycelia of these fungi grow as saprobes or parasites on a variety of substrates.Also used in foods (Blue cheese, Tempeh) and in industrial production of drugsEarly in life, a mold, a term that applies properly only to the asexual stage, produces asexual spores.Later, the same fungus may reproduce sexually, producing zygosporangia, ascocarps, or basidiocarpsSome molds go through a “fake sex” process
28HUMAN-FUNGUS INTERACTIONS Beneficial Effects of FungiDecomposition - nutrient and carbon recycling.Biosynthetic factories. Can be used to produce drugs, antibiotics, alcohol, acids, food (e.g., fermented products, mushrooms).
29Harmful Effects of Fungi Destruction of food, lumber, paper, and cloth.Animal and human diseases, including allergies.Toxins produced by poisonous mushrooms and within food (e.g., grain, cheese, etc.).Plant diseases.