Introduction to Mycology General Mycology Lecture 1 Pl P 421/521 What is a fungus? A eukaryotic, heterotrophic organism devoid of chlorophyll that obtains its nutrients by absorption, and reproduces by spores. The primary carbohydrate storage product of fungi is glycogen. Most fungi have a thallus composed of hyphae (sing. hypha) that elongate by tip growth Fungal hyphae form a network called a mycelium (pl. mycelia ) Carl Linnaeus ( ) the Father of Taxonomy Minerals exist; plants exist and live; animals exist, live and sense. Plants without obvious sexual organs were classified in Class Cryptogamia (lichens, fungi, mosses, ferns) Fungi are primitive plants under this classification of organisms. R. H. Whittakers 1969 Classification Modern Classification At least 7 kingdoms are now recognized: Eubacteria, Archaebacteria, Animalia, Plantae, Eumycota, Stramenopila (Chromista), Protoctista (Protozoa, Protista) Fungi versus fungi fungus is used inclusively for a heterogenous group of organisms that have traditionally been studied by mycologists Fungi refers to the organisms in the Kingdom Fungi, the true fungi, also called the Eumycota Kingdom Fungi Phyla:Chytridiomycota Zygomycota Glomeromycota Ascomycota (inc.Deuteromycetes) Basidiomycota Glomeromycota Kingdom Stramenopila (Chromista) Phyla:Oomycota Hyphochytriomycota Labyrinthulomycota Protists (Protoctists) Phyla:Plasmodiophoromycota Dictyosteliomycota Acrasiomycota Myxomycota Hierarchical Classification Kingdom Fungi Phylum Basidiomycota Class Basidiomycetes Order Agaricales Family Agaricaceae Genus Agaricus Species: Agaricus campestris L. Agaricus is the genus campestris is the specific epithet The genus + species is the Latin binomial; note that the genus and species are in italics (or underlined), the genus is capitalized and the species epithet is in lower case L. stands for Linnaeus, the authority Agaricus campestris is the type species of the genus Agaricus bisporus (Lange) Imbach Lange first described this fungus as Coprinus bisporus Imbach later transferred the species to Agaricus Nomenclature Nomenclature: the allocation of scientific names to the units a systematist considers to merit formal recognition. (Hawksworth et al., The Dictionary of the Fungi). The nomenclature of fungi is governed by the International Code for Botanical Nomenclature, as adopted by the International Botanical Congress. Typological Species Concept "Species are as many as were created in the beginning by the Infinite." (Linnaeus, 1758)Linnaeus Each species represented by a type specimen, designated in the original description and deposited in a recognized collection (eg., herbarium) The name is tied to the type specimen The type specimen is not necessarily typical of the entire species! How are fungi named? To determine the correct name for a taxon, certain steps must be followed, including: Effective publication Valid publication Description or diagnosis in Latin Clear indication of rank Designated type How many species of fungi exist? 80,000 species of fungi described 1,700 new species described each year Estimating the number of fungal species Hawksworth, D. L. (1991). The fungal dimension of biodiversity: magnitude, significance, and conservation. Mycological Research 95: Hawksworth, D.L. (2001) The magnitude of fungal diversity: the 1.5 million species estimate revisited. Mycological Research 105 (12): Fungi are ancient Major fungal lineages are ancient, perhaps emerging one billion years ago Fungi were present before the emergence of animals and vascular plants marine animals diversify; first appearance of most animal phyla; diverse algae Earliest terrestrial vascular plants Origin of insects, ferns, seed plants Gymnosperms become dominant, first dinosaurs, first mammals Gymnosperms dominant, evolution of angiosperms; first birds Increasing diversity of angiosperms, mammals, birds Modified from Blackwell, 2001 Mass extinction of ~95% of all species; fungal spike Mass extinction at K-T boundary; fungal spike Associations Fungi form symbiotic relationships with a number of organisms: Lichens Mycorrhizas Endophytes Decomposers As saprotrophs, particularly as decomposers, fungi are essential components of the carbon cycle and are among the few organisms that can break down lignin Pathogens Fungi are important as pathogens of animals and plants. Over 70% of all plant diseases are caused by fungi