E Kingdom Fungi

Kingdom Fungi • • • • • • •

Mycology: study of fungus Most saprophytic or parasitic; few predatory Eukaryotic Non-photosynthetic Multicellular Heterotrophic Common fungi: o mold (filamentous; on breads, oranges, etc.) o yeast (humans: unicellular; soil: multicellular) Evolution

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Oldest fossils resembling modern fungi found in Precambrian rocks ≈ 900 mill. years old Earliest fossils distinctly fungi ≈ 500 mill. years old from Ordovician period By ≈ 300 mill. years ago, late Carboniferous period, all modern divisions of fungi evolved Most present day fungi are terrestrial Speculation that fungi underwent adaptive radiation shortly after plants & animals colonized the land; also speculated that fungi arose from prokaryotes or red algae • Heterotrophic Nutrients 1. Saprophytic o live off organic compounds which they absorb from dead organisms o secrete enzymes on dead organism & absorb nutrients through cell walls o store energy in form of Glycogen 2. Parasitic o Fungus can grow on vegetation o Absorb nutrients off plants & kill it 3. Predatory o Ex. Pleurotus Ostreatus: captures and eats roundworms Structures • Chitin: polysaccharide that makes up cell wall (sugar) • Hypha: filaments; can have more than one nucleus o Septate Hypha: hypha whose cells are divided by a cell wall called a septum o Coenocyte: hypha without septum o Heterokaryotic: 2 different nuclei in 1 hypha o Homokaryotic: 2 genetically similar nuclei in 1 hypha • Mycelium: bunch or group of hypha that forms the body of the fungus

• As they grow, hypha increases in length by cell division at the tip not at the base • Dimorphism: ability to exist as 2 different forms Reproduction Asexual • Advantages: faster; high in number • 3 ways: 1. Spores: haploid versions, genetically identical, released from specialized branches 2. Fragmentation: septate hypha dry up & break apart; fragments grow into fungus 3. Budding: cell pinches off the main body & becomes new fungus Sexual • Advantage: genetic variation • Gametes are + and – • 2 hypha fuse together with the opposite gamete • The nuclei will fuse & form a diploid version • Produce spores which are distributed by wind Classification Phylum Zygomycota • Bread mold • Generally terrestrial • Coenocytic • Rhizoid: hypha that anchor the mold to surface; produce enzymes to break down food • Stolons: hypha that grow on surface • Asexual Reproduction: o Upright hypha that release spores are called sporangiophores o The tip of the sporangiophore has a sac called sporangium o Spores inside the sac are called sporangiospores • Sexual Reproduction: o + and – mycelium branching & touching each other o They fuse using conjugation o They form a septum at the tips o A gametangium forms at the end of each tip containing a nucleus o The nuclei fuse to form a zygospore or zygosporangium (diploid) o Zygospore forms a thick wall which germinates when conditions are good o Diploid nucleus undergoes meiosis to produce haploid spores which are released • Symbiotic Fungus: Mycorphizae o Symbiotic with plants o Fungus will absorb nitrogen, phosphates, & other ions to deliver to the plant root o Increases surface area of the root

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Plant provides sugar to the fungus 80% of vascular plants have similar fungus

Phylum Basidiomycota • Mushrooms, toadstools, puffballs • Called “club fungus” • The hypha begins underground & eventually forms a basidiocarp • Basidiocarp: the stem (stalk) and a cap • Under the cap are rows of gills used for reproduction • Sexual Reproduction o Each gill is lines with thousands of reproductive structures called basidia o Basidia: club-shaped & is dikaryotic ( 2 nuclei) o 2 nuclei fuse to form a diploid zygote o Zygote undergoes meiosis to form basidiospores o Spores are released and carried on the wind o Spores land & germinate into haploid mycelia o Mycelia are monokaryotic: have 1 nucleus o Different mycelia fuse to form secondary mycelia  Dikaryotic mycelia  Hyperkaryotic: genetically different nucleus o Mycelium grows into a basidiocarp Phylum Ascomycota • “sac fungus;” has sac-like reproductive compartments where spores are produced • Yeasts; molds • Fresh or salt water; soil, logs • Asexual Reproduction o Conidiophores: hypha specialized in producing spores o Conidiophore produces spores called conidium o Conidium is dispersed by wind to form new hypha • Sexual Reproduction o Ascogonium: female gametangium o Antheridium: male gametangium o Gametangium fuse together to form an ascogonium o Ascogonium form dikaryotic hyphae that produces an ascocarp o Ascocarp have individual ascus where nucleus undergoes meiosis to form haploid spores o Ascus ruptures to release ascospores o Ascospores germinate to form haploid monokaryotic hypha • Symbiotic Fungus: Lichens

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Symbiotic with photosynthetic organisms (cyanobacteria or green algae) Photosynthesizer provides sugar for fungus Fungus provides moisture, structure, & anchorage Lichen produces acids that decompose rocks, making minerals available Lichens identified by their distribution & structures 1. 2. 3.

Crustase Lichens: found on surface of rocks & trees Fruticose Lichens: are shrub-like Foliose Lichens: live on flat surface, forming a sort of mat

Phylum Deuteromycota • Imperfect fungus • Lack a sexual reproductive cycle • Asexual: conidiophores produce conidium • Conidium does not have a protective sac • Some biologists believe this phylum should be merged with Ascomycota