“The Mighty Mushroom” take a walk through a forest mushrooms are truly are the largest organisms in the forest Kingdom Fungi: not just mushrooms! approximately 100,000 species now described may be as many as 1.5 million species range from unicellular to complex multicellular organisms just about every terrestrial and aquatic environment essential decomposers in ecosystems critical for the release of nutrients into the ecosystem included with animals and plants in the Clade Opisthokonta diverged about a billion years ago

Nutrition like animals, fungi are heterotrophs cannot make their own food like algae and plants must go and find it unlike animals – they do not ingest their food (i.e. eat) fungi decompose & absorb nutrients from its environment digestion of both living and dead sources

Body Structure most common body structures of a fungus are: Reproductive structure Hyphae Spore-producing structures Mycelium 20 µm most common body structures of a fungus are: 1. multicellular filaments = mycelium 2. yeasts mycelium made up of multicellular filaments called hyphae (hypha – singular)

The Mycelium mycelium body structure: the mycelium is a haploid (n) multi-cellular organism hyphae enhances the ability to absorb nutrients a mycelium infiltrates the material on which it feeds the emphasis is on increasing mycelium length NOT width The Mycelium

Reproduction definitions: fungus reproduce asexually & sexually through the production of spores spores are haploid spores are carried by wind or water germination upon exposure to moisture to produce a new mycelium definitions: karyogamy: fusion of two haploid nuclei in fungi production of a diploid zygote plasmogamy: fusion of the cytoplasm NOT the nuclei plasmogamy produces a heterokaryotic stage – means different nuclei Haploid (n) Key Heterokaryotic (unfused nuclei from different parents) Diploid (2n) PLASMOGAMY (fusion of cytoplasm) stage KARYOGAMY (fusion of nuclei) Mycelium SEXUAL REPRODUCTION Zygote Spores GERMINATION MEIOSIS Spore-producing structures ASEXUAL

Asexual Reproduction fungal asexual reproduction: through the production of haploid spores by mitosis the mycelium is haploid and so are the spores = MITOSIS single-celled yeasts don’t produce a mycelium or spores but simply divide by mitosis or form progeny by budding Haploid (n) Key Heterokaryotic (unfused nuclei from different parents) Diploid (2n) ASEXUAL REPRODUCTION Spores GERMINATION Spore-producing structures Mycelium 10 m Parent cell Bud

Sexual Reproduction fungal sexual reproduction: consists of three stages – plasmogamy karyogamy  meiosis two hyphae of opposite mating type meet and fuse two cytoplasms fuse = plasmogamy the two nuclei do not fuse right away – hypha is now called a heterokaryon (different nuclei) Haploid (n) Key Heterokaryotic (unfused nuclei from different parents) Diploid (2n) PLASMOGAMY (fusion of cytoplasm) stage KARYOGAMY (fusion of nuclei) Mycelium SEXUAL REPRODUCTION Zygote Spores GERMINATION MEIOSIS Spore-producing structures ASEXUAL

Sexual Reproduction The mycelium is a HAPLOID multi-cellular organism hours or decades later (!) the nuclei will fuse inside the hypha = karyogamy production of a diploid zygote (2n) zygote develops into a spore producing structure called a sporangium MEIOSIS takes place in the sporangium - producing haploid spores (n) spores are dispersed to germinate and form a new mycelium Haploid (n) Key Heterokaryotic (unfused nuclei from different parents) Diploid (2n) PLASMOGAMY (fusion of cytoplasm) stage KARYOGAMY (fusion of nuclei) Mycelium SEXUAL REPRODUCTION Zygote (2n) Spores (n) GERMINATION MEIOSIS Spore-producing structures ASEXUAL Spores The mycelium is a HAPLOID multi-cellular organism

Fungal Diversity fungi are thought to be descended from a unicelluar, aquatic flagellated protist then moved to land fossils of the earliest vascular land plants have fungal associations (mycorrhizea) radiated into 5 Phyla: 1. Chytridiomycota 2. Zygomycota 3. Glomeromycota 4. Ascomycota 5. Basidiomycota Chytrids Zygote fungi Arbuscular mycorrhizal Sac Club

Molds 1,100 known species in Phylum Zygomycota diverse in lifestyles fast-growing molds e.g. Rhizopus stolonifer – black bread mold typical of a zygomycete mycelium forms as a spread of horizontal hyphae over the food – penetrates it and absorb the nutrients spore dispersal through the air eventually passes it onto other substrates for continued growth

sexual reproduction: “parents” are mycelia with hyphae or two mating types: “-” and “+” fusion of two “parental” mycelia with “+” and “-” hyphae plasmogamy produces a unique structure called a zygosporangium heterokaryotic – no nuclear fusion yet!! zygosporangium can remain dormant for months Rhizopus growing on bread Mating type (+) type (–) PLASMOGAMY Key Haploid (n) Heterokaryotic (n + n) Diploid (2n) 100 µm Young zygosporangium SEXUAL REPRODUCTION KARYOGAMY Zygosporangium Diploid nuclei MEIOSIS Sporangium Mycelium Dispersal and germination ASEXUAL Sporangia 50 µm

sexual reproduction: under favorable conditions – the nuclei in the zygosporangium fuse to make diploid (2n) nuclei (karyogamy) zygosporangium starts to make haploid spores (n) via Meiosis these spores are contained in and released by a sporangium that “sprout” from the zygosporangium this is what you see as the fluffy black stuff in black mold spores are released to land and germinate into new mycelia on a new substrate Rhizopus growing on bread Mating type (+) type (–) PLASMOGAMY Key Haploid (n) Heterokaryotic (n + n) Diploid (2n) 100 µm Young zygosporangium SEXUAL REPRODUCTION KARYOGAMY Zygosporangium (heterokaryotic) Diploid nuclei MEIOSIS Sporangium Mycelium Dispersal and germination ASEXUAL Sporangia 50 µm

Mushrooms club fungus – Phylum Basidiomycota 30,000 species Fly agaric (Amanita muscoria), a common species in conifer forests in the northern hemisphere Maiden veil fungus (Dictyphora), a fungus with an odor like rotting meat Shelf fungi, important decomposers of wood Puffballs emitting spores club fungus – Phylum Basidiomycota 30,000 species includes the mushrooms, shelf fungi, molds and mycorrizhae, rusts and smuts important decomposers of wood saprophoric (decomposing) and parasitic species (rusts and smuts)

The Common Mushroom basidium = “little pedestal” pileus basidium = “little pedestal” spore forming part of the mushroom the part of the mushroom we see is a reproductive structure called a basidiocarp basidiocarp = cap (pileus) with the gills on the underside + the supporting stalk = stipe the basidiocarp is actually a large aggregation of hyphae forming the mushroom underground is the actual mycelium basidiocarp stipe stipe gills

sexual reproduction: two haploid mating types ‘+’ and ‘–’ undergo plasmogamy and a heterokaryotic mycelium made of two different nuclei per cell forms rain or temperature changes induce the mycelium to form many basidiocarps (mushroom) that poke up above the ground PLASMOGAMY Key Haploid (n) Dikaryotic (n + n) Diploid (2n) SEXUAL REPRODUCTION KARYOGAMY MEIOSIS Mycelium Basidium containing four haploid nuclei Dispersal and germination Basidium 1 µm Mating type (+) type (–) Haploid mycelia Gills lined with basidia Basidiocarp Basidia (dikaryotic) Diploid nuclei Basidiospore Basidiospores

sexual reproduction cont…..: the gills of the basidiocarp are lined with spore-producing structures (i.e. sporangia) called basidia (basidium = singular) within each basidium the 2 nuclei fuse to make a diploid parental cell (i.e. karyogamy) the parental cell undergoes meiosis 4 haploid nuclei total per basidium each haploid nuclei develops into a basidiospore (4 basidiospores per basidium) basidiospores are released and are carried by the wind – germinate into new mycelia which rapidly undergo more sexual reproduction 4 basidiospores on a basidium PLASMOGAMY Key Haploid (n) Dikaryotic (n + n) Diploid (2n) SEXUAL REPRODUCTION KARYOGAMY MEIOSIS Dikaryotic mycelium Basidium containing four haploid nuclei Dispersal and germination Basidium 1 µm Mating type (+) type (–) Haploid mycelia Gills lined with basidia Basidiocarp (dikaryotic) Basidia Diploid nuclei Basidiospore Basidiospores

Yeasts 1500 species of unicellular fungi not a single taxonomic or phylogenic grouping divided up between Phylum Ascomycota & Phylum Basidiomycota often a synonym for the species Saccharomyces cerevisiae but there are several species of yeasts

Yeasts are chemotrophs – convert carbohydrates into CO2 and alcohol (fermentation) yeasts are either obligate aerobes (for cellular respiration) or anaerobic (fermentation) naturally occurring on skins of fruits & berries – even on the skin or epithelial linings of humans Candida albicans - yeast infections or athlete’s foot also found in guts of mammal and insects e.g. bees and ants even in deep sea environments most reproduce asexually through budding or fission (mitosis)

Fungal Associations: Lichens Lichens: 25,000 species fungus + green algae (or cyanobacteria) algae provide organic compounds, the cyanobacteria fix nitrogen algae nestle among the fungal hyphae and are protected types of lichens: 1. Crustose lichens – grow as a crust on a surface 2. Foliose lichens – leafy in appearance 3. Fructicose lichens – shrublike with branching and intertwined fibrous parts A fruticose (shrub-like) lichen A foliose (leaf-like) lichen Crustose (crust-like) lichens

Lichens most reproduce asexually: either through fragmentation or by the formation of soredia – small clusters of hyphae with embedded algae - may be carried by the wind to new locations Fungal hyphae Algal cell Soredia Algal layer Fungal hyphae Ascocarp of fungus 10 µm