Fungi: Structure and Nutrition
Vegetative structure
filamentous hyphae
mycelium
Nutrition Æ hetrotrophs
absorptive
Fungi
Fungi: Cell Characteristics
Monokaryotic
Kingdom: Fungi
General Characteristics
Nutrition
Æ Heterotrophic & absorptive
Vegetative structureÆ Filamentous - hyphae &
mycelium
Motility
Æ Nonmotile
Flagella – only chytrids
Cell Wall chemistry Æ Chitin
Cell division
Æ Nuclear mitosis
Meiosis
Æ Zygotic
Diversity
Æ >73,000 species
4 Phyla
Multinucleate
Dikaryotic
Heterokaryotic
Heterokaryon formation in
Fusarium oxysporum
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Major Groups of Fungi
Kingdom: Fungi - Classification
Chytridiomycota…flagellate fungi
Zygomycota
Chytridiomycota
Zygomycota
…zygote fungi
Ascomycota
…sac fungi
Basidiomycota
… club fungi
Ascomycota
Basidiomycota
Fungi
1
Imperfect Fungi
•
•
•
•
No sexual phase
Reproduce by conidia
20,000+ species
mostly ascomycetes
Imperfect Fungi: Importance
Conidia
Conidiophore
•
•
•
•
Aspergillus
Penicillium
Tolypocladium
Microsporum
Aflatoxins
Antibiotics
Cyclosporine
Ringworm
Chytridiomycota
Characteristics
1. Unicells or mycelial hyphae
2. Cell wall chitin
3. small subunit rRNA … like fungi
4. flagellated gametes
5. sporic meiosis
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Phylum: Chytridiomycota
Kingdom: Fungi
Phylum: Zygomycota…zygote fungi
Germinating
Haploid gametophyte
Fig. 30.09b(TE
Art)
(n)
zoospore (n)
Genus: Allomyces
A soil chytrid
S
OSI
MEI
Young
Gametophyte
(n)
Resistant
Sporangium (2n)
Mature
Diploid
Gametophyte
Zoospores (2n)
Mature
( n)
Sporophyte
Asexual
n
2n
( )
(2n)
sporangium
Female
Germinating
gametangium
sporophyte
Haploid
gametes (n)
Young
Sporophyte
FUSION
Male
(2n)
gametangium
Distribution &
abundance
Cytology
1100 species …mostly
Opportunistic saprotrophs
Multinuclease mycelium…
Non-septate hyphae
Defining characteristic Zygospore
Germinating sporophyte (2n)
2
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Phylum: Zygomycota…zygote fungi
Life Cycle: Zygomycota
Sporangiophore
Sporangium Art) Rhizoid
Fig.Spores
30.10(TE
Coenocytic hyphae
Mycelium
Sporangium
Zygospores/
Zygosporangium
Sporangium
Mating
strain
Hypha
MEIOSIS
(occurs
during
germination)
Sporangium
with
Rhizoids
2n
n
Mating
strain
FUSION OF
GAMETANGIA
Germinating
zygosporangium
Zygosporangium
Economic Importance Zygomycota
Plant pathogens strawberries, apples,
tomatoes, bread mold
Kingdom: Fungi
Phylum: Ascomycota …sac fungi
Distribution &
abundance
45,000 + species
(75% of known fungi)
Cytology
Partially septate
hyphae
Dikaryotic stage
Animal pathogens mucormycoses
Defining
characteristic
Organic acids: citric acid
& gluconic acid
Gametangia
Septum or
Cross Wall
Ascus & Ascospores
Ascus & ascospores
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Fig. 30.12c(TE Art)
Life Cycle: Ascomycota
Ascospore Asexual spores (conidia)
Each haploid
Strain
nucleus divides
Ascogonium
once by mitosis
Antheridium
Ascus
MEIOSIS
Strain
Monokaryotic
n
Plasmogamy
Dikaryotic stage
2n
Kingdom: Fungi Phylum: Ascomycota
Economic Importance
•
•
•
•
Saccharomyces
Ceratocystis
Morchella
Candida
yeast
Dutch elm disease
morels
yeast – thrush
Zygote
Dikaryotic
hyphae
Produce Asci
Karyogamy
Ascocarp
(c)
3
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Kingdom: Fungi
Phylum: Basidiomycota
Distribution &
abundance
22,000+ species
Cytology
Partially septate
hyphae
Dikaryotic stage
Life Cycle: Basidiomycota
Gills lined
Fig. 30.11b(TE Art)with basidia
…club fungi
Basidiocarp
Defining
characteristic
n+n
n
Secondary mycelium
(dikaryotic)
2n Zygote
Basidium
MEIOSIS
Strain
Basidium and
Basidiospores
Strain
Basidiospores
Primary mycelium
(monokaryotic)
Kingdom: Fungi
Most fungi produce
fruiting bodies
Kingdom: Fungi Phylum: Basidiomycota
Economic Importance
• Destructive….wood rot fungi
• Food… Agaricus
• Plant pathogens rusts and smuts
Spore production by basidiomycetes
Puffball:
7 X 1012
Bracket fungus
50 X 109
Agaricus
Fungal Symbioses
1. Lichens
2. Mycorrhizae
3. Endophytes
4. Mutualistic Animal Symbioses
5. Fungal Parasites and Pathogens
16 X 109
4
Fungal associations – Lichens
Lichens
Lichen = Fungus + photosynthetic partner
Found in inhospitable environments
– Rocks, tree branches, alpine environments
Pioneer organisms…
organisms… break down rocks
Grow very slowly
– 1-2mm per year
Fruticose
Sensitive to air pollution
– Low tolerance for SO2
Foliose
Food source for animals like caribou
Crustose
Fig. 30.15
Lichen structure
Fungal associations
Mycorrhiza = Fungus + plant root
Ectomycorrhiza (Lactarius) on Pinus
Ectomycorrhiza (Amanita) on Pinus
Fig. 30.16a(TE Art)
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Mycorrhizae
Arbuscular mycorrhiza
1. Penetrate cell walls
2. Mostly zygomycetes
(Glomales group)
3. 200,000 plant species
Mutualistic Animal Symbioses
Ectomycorrhiza
1.
2.
3.
4.
Leaf-cutter distribution
Do not penetrate cells
Mostly basidiomycetes
About 5000 species
Mostly in trees
Leaf-cutter ants provide food for fungi.
Fungus provides food for ants.
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Fungal Animal Parasites and Pathogens
Fungal Plant Pathogens – Root rot fungus
1. Animal Parasites
Batrachochytrium Æ Chytridiomycosis… amphibian cutaneous chytridiomycosis
Fungal spore
discharge tubes
20 acres of Armillaria – a root rot fungus
infecting Douglas Fir
Harlequin frog (Atelopus)
2/3 of 110 species are extinct
Fungal Plant Parasites
Fungal metabolites
amanitiin
Claviceps causes ergot in rye
1. Convulsive ergotism
St. Anthony’s fire
2. Ergotate
Amanita caesarea
Amanita phalloides
Fungi – Psychoactive metabolites
• Physical Effects
– Slightly blurred vision, increased salivation
– Nausea, overwhelming for some, mild for
others
– Marked analgesia
– Pupil dilation, glassy-eyed stare
A. muscaria
Euphoria: Feelings of peace and well being
Sedative or Extreme energy bursts
Dream State: highly detailed, colorful, a great sense of lucidity.
Body Perception: dramatic shifts in body perception & motor skills:
Internal Dialogue: strong sense of an internal discussion
Synesthesia: is somewhat common, smelling words, tasting colors
Sociability: Group interaction can become incoherent, frequent changes
in topic, non-linear conversations
6
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Major Groups of Fungi
END
Fungi
Zygomycota
Chytridiomycota
Ascomycota
Basidiomycota
Fungi
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