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 Fusion of hyphae* Nuclear fusion Meiosis to give spores Haploid mycelia of different mating types Dikaryotic mycelium gives fruiting body Diploid stage 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

Chytridio mycetes Zygo mycetes

Cell wall of chitin+ cellulose in some sp

Asco mycetes

Mycelium coenocytic coenocytic septate

Basidio mycetes

septate

Deutero mycetes

septate Repro duction flagellated zoospores zygospores from black zygo sporangia ascospores from cup, sac, morel basidio spores from mushroom no sexual stages

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

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

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

Cup fungi Tissues within the ascocarp 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.