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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
Outline
  • Characteristics
    • Structure
    • Reproduction
  • Evolution
    • Sac Fungi
    • Yeasts
    • Club Fungi
    • Smuts and Rusts
    • Imperfect Fungi
  • Symbiotic Relationships
characteristics of the fungi
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
structure of fungi
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
reproduction of fungi
Reproduction of Fungi
  • Both sexual (in most) and asexual reproduction
  • Sexual reproduction involves three stages:
    • Haploid Hyphae
    • Dikaryotic Stage
    • Diploid Zygote
reproduction of fungi7
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
diversity of fungi zygomycota
Diversity of Fungi:Zygomycota
  • Zygospore Fungi
  • Phylum Zygomycota
    • Mainly saprotrophs decomposing animal and plant remains
    • Black bread mold - Rhizopus stolonifer
diversity of fungi zygomycota11
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
diversity of fungi sac fungi
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
sac fungi reproduction asexual
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)
sac fungi reproduction sexual
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
sac fungi reproduction yeasts
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
diversity of fungi the club fungi
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
the club fungi reproduction
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)
the club fungi smuts and rusts
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
symbiotic relationships lichens
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
symbiotic relationships lichens27
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
symbiotic relationships mycorrhizae
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
review
Review
  • Characteristics
    • Structure
    • Reproduction
  • Evolution
    • Sac Fungi
    • Yeasts
    • Club Fungi
    • Smuts and Rusts
    • Imperfect Fungi
  • Symbiotic Relationships
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