Introduction to Mycology General Mycology Lecture 1 Pl

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 (1707 -1778) 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. Whittaker’s 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 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. , 1995. 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) • 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: 641 -655 • Hawksworth, D. L. (2001) The magnitude of fungal diversity: the 1. 5 million species estimate revisited. Mycological Research 105 (12): 1422 -1432.

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

Mass extinction at K-T boundary; fungal ‘spike’ Increasing diversity of angiosperms, mammals, birds Gymnosperms dominant, evolution of angiosperms; first birds Gymnosperms become dominant, first dinosaurs, first mammals Mass extinction of ~95% of all species; fungal ‘spike’ Origin of insects, ferns, seed plants Earliest terrestrial vascular plants marine animals diversify; first appearance of most animal phyla; diverse algae Modified from Blackwell, 2001

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