True Fungi break down dead organic material provide numerous drugs foods like mushrooms Plant and animal diseases

Characteristics of fungi Fungi exist primarily as filamentous threads, the hyphae, forming a mass, a mycelium. Normally never see the mycelium, only the fruiting bodies. Cell walls contain chitin.* Reproduction is due to fusion of hyphae* Fungi are heterotrophic by absorption

Groups of fungi Chytridiomycota (chytrids) Zygomycota (bread molds) Ascomycota (yeasts and sac fungi) Basidiomycota (club fungi) Deuteromycota (asexual forms of ascomycetes and basidiomycetes)

Generalised Life cycle of fungi Meiosis to give spores Fusion of hyphae* Nuclear fusion Dikaryotic mycelium gives fruiting body Diploid stage Haploid mycelia of different mating types With the exception of the chytrids, the life cycle follows the same generalised pattern. Haploid hyphae fuse to form a mycelium which contains nuclei from the two hyphae. The duration of this ‘dikaryotic’ phase is different in the differing groups of fungi and therefore characteristic. At some stage the nuclei fuse to form a diploid cell, and there is usually immediate meiosis to give spores. Not in chytrids* Zygomycetes - V. small fruiting body Ascomycetes - small fruiting body Basidiomycetes - long-lived hyphae then a large fruiting body

Comparison of different groups

Chytridiomycota (chytrids) The oldest fossil fungi so far known and may form a ‘missing link’ with protists. Flagellated zoospores fuse, their nuclei fuse then immediate meiosis to give spores

Zygomycota (bread molds) Important decomposers Dominant haploid phase with dikaryon restricted to formation of zygosporangium asexual spores are produced

The life cycle of a zygomycete Spores produced by mitosis Zygospores Spores produced by meiosis Sporangium forms by mitosis The life cycle of a zygomycete Spores germinate to give mycelium Coenocytic mycelia of 2 mating types Hyphae grow to each other Gametangia develop Zygosporangium develops Zygosporangium formed

Ascomycota (yeasts and sac fungi) Sexual spores (ascospores) are produced in a specialized sac-like structure called an ascus on the surface of an ascocarp. Reproduced asexually by conidia Decomposers that include economically important foods such as truffles and Morels and pests such as powdery mildews and ergots. Yeasts used in baking and brewing.

Life cycle of an ascomycete Nuclear fusion then Ascospores in asci by meiosis Life cycle of an ascomycete Haploid septate hyphae Anther- idium (‘male’) Asco- gonium ‘female’ Dikaryotic hyphae

Sporing structures (ascocarps) A vegetative layer of ‘sterile’ dikaryotic hyphae (2 nuclei) forms the body of the ascocarp with a layer of asci on the surface (produce spores)

Sporing structures

Tissues within the ascocarp Cup fungi Morels Flask fungi Sterile body of ascocarp formed from dikaryotic hyphae Layer of asci

Basidiomycota (club fungi) Septate hyphae Produce long-lived dikaryons (mycelia where the cells have 2 nuclei) Produce sporing structures, the basidia, on basidiocarps. Wood rotting fungi Rusts Smuts Mushrooms Puffballs Life cycle a bit like ascomycetes, but individual spores produced

Yeasts Unicellular forms of ascomycetes and basidiomycetes. Some reproduce sexually some don’t. Baking Brewing Human pathogens e.g. Candida

Deuteromycota (asexual forms of ascomycetes and basidiomycetes) No sexual stages known and propagate solely by spores called conidia on structures called conidiaphores. Includes commercially important species such as Penicillium (gives penicillin from fungal fermentations) Conidia Conidiophore Mycelium

Lichens Lichens are unusual creatures. A lichen is a combination of two organisms which live together intimately. Most of the lichen is composed of fungal filaments, but living among the filaments are algal cells, usually from a green alga or a Cyanobacterium.