Topic 13 - Fungi

Question 1

Fungal Ancestry

Answer 1

• Shared with the Nucleariids
• Unicellular opisthokont protists
• Multicellularity evolved in the Fungi
• Many Chytrids are unicellular

Question 2

Typical Fungal Characteristics

Answer 2

• Most are multicellular
• Cell walls made of chitin
• Absorptive heterotrophs
  
  • Store carbohydrates as glycogen
• Filamentous, syncytial body plan
  
  • Hyphae
  • Mycelium
• Reproductive fruiting bodies
• Haplontic life cycle (most)
  
  • Asexual and sexual cycles

Question 3

Typical Fungal Life Cycle

Answer 3

• Asexual life cycle
• Haplontic life cycle
  
  • Diploid zygote
  • Haplooid spores
  • Haploid mycelium
  • Plasmogamy
    
    • heterokaryon
    • Dikaryotic stage
  • Karyogamy

Question 4

The Fungus Body Plan

Answer 4

• Hyphae
  
  • Tubular
  • Branched
  • Septate
  • Coenocytic
• Mycelium
  
  • Aggregation
• Fruiting Body
  
  • Seasonal structure
  • Spore dispersal

Question 5

Biology of Fungi

Answer 5

• Parasitic
  
  • Haustoria
• Predatory
  
  • Arthrobotrys

Question 6

What are the major fungal phyla?

Answer 6

• Almost 100 000 species of fungi described
• 5 Major fungal phyla
  
  • Ascomycota
  • Basidiomycota
  • Glomeromycota
  • Zygomycota
  • Chitridiomycota

Question 7

Phylum Chytridiomycota

Answer 7

• The Chytrids
  
  • Basal clade of fungi
  • 1000 species
    
    • 20 clades
• Most are aquatic
  
  • Flagellated structures
    
    • Gametes
    • Zoospores
      Have a flagellum
• Unicellular or colonial

Question 8

Phylum Zygomycota

Answer 8

• Some moulds and other fungi
  
  • Mostly coenocytic hyphae
• Asexual reproduction
  
  • Hospitable environments
• Sexual reproduction
  
  • Inhospitable conditions
• Black bread mould
• Pilobolus
• Enterobryus

Question 9

Zygomycota Life Cycle

Answer 9

• Asexual reproduction
  
  • Sporangia
• Sexual reproduction
• Two mycelia ( 2 mating types)
• Plasmogamy
  
  • Heterokaryotic zygosporangium
• Karyogamy
  
  • Diploid nuclei
  • Meiosis
  • Spores

Question 10

Phylum Glomeromycota

Answer 10

• Very small but VERY significant group
  
  • Essential ecological role
• Arbuscular mycorrhizae
  
  • A mutualistic relationship
  • 80% of plant species

Question 11

Phylum Ascomycota

Answer 11

• Largest phylum of fungi (65,000 species)
• The sac fungi
  
  • Ascocarp fruiting bodies
  • Ascospores
• Septate hyphae
• Unicellular yeasts

Question 12

Ascomycota Life Cycle

Answer 12

• Asexual reproduction
  
  • conidiophores
  • Conidia
• Sexual reproduction
  
  • Conidium (-) fuses with mycelium (+)
• Dikaryotic stage extended
  
  • Hyphae
  • Asci
• Within the ascus
  
  • Nuclear fusion: zygote
  • Meiosis then mitosis: 8 ascospores/ascus
  • Germination

Question 13

Dutch Elm Disease

Answer 13

• Introduced in 1930s
  
  • Reached Manitoba in 1975
• Blue stain fungus grows in the xylem
  
  • An ascomycete
• Bark beetles burrow into trees
• Spores transferred to new trees by beetles
• Repair by host plugs tunnels with resin

Question 14

Phylum Basidiomycota

Answer 14

• The club fungi
  
  • Basidiocarp fruiting bodies
  • Basidiospores
• Septate hyphae
• Long-lived dikaryotoic stage
• Important decomposers of wood
• Economic Importance

Question 15

Basidiomycota Life Cycle

Answer 15

• NO asexual reproduction
• Sexual reproduction
  
  • Basidium
    
    • 4 basidiospores
  • Mycella of 2 mating types . (+ & -) grow together
• Dikaryotic stage
  
  • Hyphae
  • Fruiting bodies
  • Basidia
• Within the basidia
  
  • Nuclear fusion: 2n basidium
  • Meiosis in basidium
    
    • 4 haploid nuclei

Question 16

Linchens

Answer 16

• Symbioses
• Mycobiont
  
  • Fungi
• Photobiont
  
  • Alga, cyanobacteria