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Outline. Characteristics Structure Reproduction Evolution Sac Fungi Yeasts Club Fungi Smuts and Rusts Imperfect Fungi Symbiotic Relationships. Characteristics of the Fungi. Kingdom Fungi contains 80,000 spp Mostly multicellular eukaryotes that share a common mode of nutrition

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Outline

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  1. The Fungi

  2. Outline • Characteristics • Structure • Reproduction • Evolution • Sac Fungi • Yeasts • Club Fungi • Smuts and Rusts • Imperfect Fungi • Symbiotic Relationships

  3. Characteristics of the Fungi • Kingdom Fungi contains 80,000 spp • Mostly multicellular eukaryotes that share a common mode of nutrition • Heterotrophic • Cells release digestive enzymes and then absorb resultant nutrient molecules • Some are parasitic • Several have mutualistic relationship

  4. Structure of Fungi • Body (thallus) of most fungi is multicellular mycelium (yeasts are unicellular) • Consists of a vast network of thread-like hyphae • Septate fungi have hyphae with cross walls • Nonseptate fungi are multinucleated • Hyphae grow from tip • Give the mycelium a large surface area per unit volume • Cell walls of chitin, like insect exoskeleton • Excess food stored as glycogen as in animals • Possibly evolved from red algae - both lack flagella

  5. Mycelia and Hyphae of Fungi

  6. Reproduction of Fungi • Both sexual (in most) and asexual reproduction • Sexual reproduction involves three stages: • Haploid Hyphae • Dikaryotic Stage • Diploid Zygote

  7. Reproduction of Fungi • During sexual reproduction, hyphae from two different mating types fuse • Hyphae that contain paired haploid nuclei are said to be dikaryotic • Nuclear fusion produces diploid nucleus, which produces haploid windblown spores by meiosis • Spores germinate directly into haploid hyphae without embryological development • Asexual reproduction usually involves the production of windblown spores • Unicellular yeasts reproduce by budding

  8. Dispersal of Spores

  9. Diversity of Fungi:Zygomycota • Zygospore Fungi • Phylum Zygomycota • Mainly saprotrophs decomposing animal and plant remains • Black bread mold - Rhizopus stolonifer

  10. Black Bread Mold,Rhizopus stolonifer

  11. Diversity of Fungi:Zygomycota • Life cycle • Hyphae of opposite mating types grow toward each other • Hyphae swell at tips; cross walls develop behind each end; form gametangia • Gametangia merge resulting in a large multi-nucleate cell • Nuclei of the two mating types pair and then fuse • A thick wall develops around the zygospore • The zygospore becomes dormant for period • Sporangiophore(s) then sporangia develop, spores released • Spores dispersed by air currents; germinate into mycelia

  12. Diversity of Fungi:Sac Fungi • Phylum Ascomycota - about 60,000 species of sac fungi • Most are saprotrophs that digest resistant materials containing cellulose, lignin, or collagen • Most are composed of septate hyphae • Neurospora, experimental organism for the one-gene-one-enzyme studies • Morels and truffles, famous gourmet delicacies revered throughout the world • Many plant diseases: Powdery mildews; leaf curl fungi; ergot of rye; chestnut blight and Dutch elm disease • Aspergillus and Candida cause serious human infections • Talaromyces (formerly Penicillium) is source of penicillin

  13. Sac Fungi:Reproduction - Asexual • Life cycle • Asexual reproduction is the norm • Yeasts usually reproduce by budding • A small bulge forms on side of cell • Receives a nucleus and gets pinched off and becomes full size • The other ascomycetes produce spores called conidia or conidiospores • Vary in size and shape and may be multicellular • Conidia usually develop at the tips of conidiophores • Conidiophores differ in appearance and are diagnostic • Conidia are windblown • Conidia of Cladosporium cause allergies - concentrations of more than 35,000 conidia/m3 over Leiden (Germany)

  14. Asexual Reproduction in Sac Fungi

  15. Sac Fungi:Reproduction - Sexual • Life cycle, cont. • Sexual reproduction • Ascus refers to the fingerlike sac that develops during sexual reproduction • Asci usually surrounded and protected by sterile hyphae within an ascocarp • In cup fungi, ascocarps are cup-shaped • In morels they are stalked and are pitted like the surface of the moon • Haploid hyphae fuse to make diploid nucleus • Mitosis and then meiosis produces 8 ascospores

  16. Sexual Reproduction in Sac Fungi

  17. Black Mold

  18. Tineas

  19. Sac Fungi:Reproduction - Yeasts • Term “yeasts” is loosely applied to unicellular fungi, many of which are ascomycetes • Budding is common form of asexual reproduction • Sexual reproduction results in the formation of asci and ascospores • When some yeasts ferment, they produce ethanol and carbon dioxide

  20. Diversity of Fungi:The Club Fungi • Phylum Basidomycota – 22,000 spp • Familiar toadstools, mushrooms, bracket fungi, puffballs, stinkhorns – some deadly poisonous • Also plant diseases such as the smuts and rusts • Mycelium composed of septate hyphae

  21. The Club Fungi:Reproduction • Usually reproduce sexually • Haploid hyphae fuse, forming a dikaryotic (n + n) mycelium • Dikaryotic mycelium forms fruiting bodies called basidiocarps • Contain club-shaped structures called basidia • Nuclear fusion followed by meiosis produces basidiospores (up to 40,000,000 per hour)

  22. Club Fungi

  23. Club Fungi

  24. The Club Fungi:Smuts and Rusts • Smuts and rusts are club fungi that parasitize cereal crops • Great economic importance because of annual crop losses • Do not form basidiocarps • Life cycle of rusts often requires two different plant host species • Black stem rust of wheat uses barberry bushes • Blister rust of white pine uses currant and gooseberry bushes • Eliminating these bushes in crop areas keeps rusts in check • Wheat rust • Controlled by breeding new resistant strains of wheat • Requires continuous development, because rust can mutate

  25. Smuts & Rusts

  26. Symbiotic Relationships:Lichens • Symbiotic association between a fungus and a cyanobacterium or green alga • Specialized fungal hyphae penetrate photosynthetic symbiont • Transfer nutrients directly to the fungus • Possibly mutualistic, but fungal symbiont probably a parasite of photosynthetic symbiont • Photosynthetic symbiont independent • Fungal symbiont usually can’t grow alone

  27. Symbiotic Relationships:Lichens • Three morphological types • Compact crustose lichens - seen on bare rocks or on tree bark • Fruticose lichens – shrub-like • Foliose lichens - leaf-like • Can live in areas of extreme conditions and contribute to soil formation • Sensitive indicators of air pollution

  28. Lichen Morphology

  29. Symbiotic Relationships:Mycorrhizae • Mutualistic relationships between soil fungi and the roots of most familiar plants • Give plant greater absorptive surface • Help plants acquire mineral nutrients in poor soil • Fungal symbiont usually a sac fungus • Hyphae may enter cortex of root, but not cytoplasm • Ectomycorrhizae form a mantle that is exterior to the root, and they grow between cell walls. • Endomycorrhizae penetrate only the cell walls • Earliest fossil plants have mycorrhizae associated with them

  30. Plant Growth Experiment

  31. Review • Characteristics • Structure • Reproduction • Evolution • Sac Fungi • Yeasts • Club Fungi • Smuts and Rusts • Imperfect Fungi • Symbiotic Relationships

  32. The Fungi

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