FUNGI Huge group of very successful organisms – found in virtually all ecological niches on Earth. Largest single organism on Earth is a fungus. ( Armillaria ostoyae) ~100,000 species* so far described, but there are likely many more (up to 2 million). –Inadequate sampling –*Species? Individual? Traditionally, fungi (particularly mushrooms) have been studied by botanists, however, they are “achlorophyllous”.
Fungi vs fungi Fungi are a monophyletic (closely related) group of organisms all sharing a common ancestry and evolutionary history, and sharing many common characteristics. “TRUE Fungi” fungi are organisms that share many characteristics with Fungi (and so superficially resemble them), but DO NOT share a common ancestry and evolutionary history. “fungus-like organisms”
Characteristics of Fungi Heterotrophic (Saprobic or Parasitic) –Extracellular digestion Enzymes (hydrolytic, proteases, etc.) break down macromolecules dimers & monomers. These digestion products are then absorbed. –An adaptive morphology allows for sufficient surrounding of food and sufficient energy intake to counteract the energy spent in digestive enzyme production…
Characteristics of Fungi Most are filamentous (adaptive morphology for increased surface area). –Vegetative body called a Mycelium (pl. Mycelia). –A Mycelium is composed of numerous Hyphae (sing. Hypha), each 1 cell wide.
Characteristics of Fungi Some are small “uni-cells” Yeasts Chytridiomycota Yeasts Chytrids Filamentous Stage
Characteristics of Fungi Cell Wall
Characteristics of Fungi Cell Wall is composed of Chitin. –Complex, N-containing Polysaccharide (a carbohydrate polymer). –Helps maintain osmotic pressure in the cells.
Characteristics of Fungi The vegetative (somatic) body of a fungus is the Mycelium: the absorptive, “adult”, feeding stage.
Hyphae Septa (sing. Septum) are partitions between hyphal cells. Aseptate taxa are coenocytic (multi- nucleate). Septate taxa typically have a Septal Pore.
Characteristics of Fungi Rhizomorphs – root like masses of hyphae.
Characteristics of Fungi A fraction of the vegetative mycelium is devoted to reproduction. Specialized hyphae bearing Spores. Spores are tiny propagules.
Spores Dispersal Protection Survival Reproduction. Asexually-produced spores are disseminative. Sexually-produced spores are reproductive AND disseminative.
Asexually-Produced Spores Spores are borne on hyphal tips called Conidia (sing. Conidium) or in Sporangia (sing. Sporangium).
Asexually-Produced Spores Produced by Mitosis & Cell Division. Clones (genetically-identical progeny) are produced.
Sexually-Produced Spores Spores are borne on unique and specialized structures, depending on the type of fungus. Produced by Meiosis & Cell Division. Genetically-unique progeny are produced. Sexual Reproduction = combined genetic contributions of two parents. Life cycles.
Life Cycles MEIOSISFERTILIZATION HAPLOID STAGE (1N) DIPLOID STAGE (2N)
Gametic Life Cycle 1N 2N
Gametic Life Cycle Meiosis produces gametes (sperm or egg). 1N 2N
Zygotic Life Cycle Meiosis produces spores (mini-zygotes). 1N 2N (Spores) (Gametes here produced by Mitosis)
Classification of Fungi
Fungi comprise a monophyletic group broken into 4 lineages (therefore also 4 Phyla): –Phylum: Chytridiomycota –Phylum: Zygomycota –Phylum: Ascomycota –Phylum: Basidiomycota “Phylum”: Deuteromycota is an artificial group representing fungi that do not or have yet to exhibit a sexual stage (meiosis & syngamy).
Phylogeny of Fungi Morphological Character state changes
Ascomycota Ascus (sac) is where the sexual spores (Ascospores) are borne. 8 Ascospores are typical in each ascus.
Ascomycete Life Cycle
Basidiomycota The ‘Club’ Fungi
Basidiomycota Sexual Basidiospores borne on a Basidium. 4 spores per Basidium. Basidium Basidiospores
Basidiomycete Life Cycle
Studying FUNGI Both Macroscopic and Microscopic organisms. Cultures –1-member, 2-member –Growth Media (sing. Medium) Agar, Broth –Petri Plates or Culture Tubes.
Significance & Importance 1.Sources of important chemicals –Medicines. Antibiotics like Penicillin, Cephalosporin. Eastern Medicine, herbal remedies, anti-tumor, etc. –Metabolites Plant growth hormones, steroids. –Mycotoxins, biological control agents. –Transformative enzymes. Alcohol fermentation with CO 2 production by Saccharomyces cerevisiae (yeast). Cheese ripening, sausage production, miso
Significance & Importance 2.Food sources. –Mushrooms Shiitake, Oyster, Porcini, Portobello, Morel, Truffle… Wild Mushrooms….Poisonings. –Cheeses, Miso, Beer, Wine, Bread. –Cultivation…by humans and other animals. 3.Spiritual ceremony & shamanism. –Natives of Mexico & Central America – hallucinogenic religious rites involving Psilocybe cubensis. (more recently studied by Wasson, McKenna, & others). –Mushroom effigies associated with many primitive (& modern) cultures.
Significance & Importance 4.Ecosystem Contributions –Decomposers of cellulose, lignin (wood). (often found in human-manufactured items) –Control of nutrient cycling. –Soil retention. –Mycorrhizal associations with plants. 5.Plant pathogens –Potato blight (Oomycete) –Chestnut blight (Cryphonectria parasitica) –Dutch elm disease (Ophiostoma sp.) –Ergot of Rye (Claviceps purpurea)