Fungi
Basic characteristics of Fungi
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Eukaryotic
Multicellular (except yeast)
Heterotrophic
Mode of nutrition: absorbtive
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Secrete hydrolytic enzymes
Digestion occurs externally
Composition of cell walls differs-chitin
CHARACTERISTIC
A.
B.
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Filamentous Growth Form
1. Hyphae
A.
a. stolons
B.
b. rhizoids
2. Mycelium
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a. If strung end-to-end would be many meters long
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b. Surrounds and penetrates substrate
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c. Composition of cell wall-Polysaccharide plus
chitin (not cellulose)
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1. Same component of arthropod exoskeleton
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2. More resistant to bacterial degradation
Economic Value of Fungi
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A. Harmful- Cause decay, rot, spoilage and
serious plant and animal diseases
B. Beneficial
1. Manufacture of bread and beer
2. Flavor cheese, wine and other foods
3. Industrial production of acids,
antibiotics and chemical syntheses
4. Detoxify environment
5. Mycorrhizae facilitate absorption of
essential nutrients by plant roots
Fungal Structures
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Mycelium: Mostly underground; feeding
body composed of interwoven:
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Hyphae: threadlike structures
Septa: divide hypae into cells
Haustoria: tips of hyphae
Cell walls: chitin
Some are coenocytic (aseptate)
See fig. 31.1 and 31.2
Life cycle/Reproduction
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May be asexual or sexual
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Some only have sexual repro in response
to an environmental change
ZYGOMYCETES
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Structure
a. Hyphae
1. Stolon-grow horizontally
2. Rhizoids- grow down
3. Sporangiophore-grow upward
b. Sporangium(2N)
1. Form spores(N)
2. Meiosis
ZYGOMYCETES
BASIDIOMYCETES
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1. Types
 a. Mushrooms, jelly fungi, puffballs, rusts and smuts
 b. Include edible and poisonous varieties
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2.
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a.
b.
Reproduction
Sexual
Asexual reproduction rare in basidiomycetes
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3. Structures
 a. Stipe
 b. Gills
 c.
Cap
 d. Annulus
BASIDIOMYCETES
ASCOMYCETES
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1. Types
 a. Beneficial forms include yeast, penicillin, morels and
truffles, cheese mold, neurospera
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b. Harmful forms include chestnut blight, Dutch elm disease,
Clavis purpurea-LSD
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c. Reproduction
 1. Asexual reproduction is common
 2.
Sexual
ASCOMYCETES
DEUTEROMYCETES
• 1. Fungi that Have Lost the Ability to
Reproduce Sexually
• 2. Have great economic importance
– a. Many are human and plant pathogens
–1.
ring worm
–2.
athletes foot
• b. Others produce important chemicals
including penicillin
• V. Fungal Relatives
MYCORRHIZAE
• b. Mycorrhizae
• 1. General characteristics
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a. Most plant roots associated with certain fungi
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b. Fungus aids in transfer of soil nutrients into roots
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c. Plant provides organic carbon to fungus
• 2. Advantages of mycorrhizial associations
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a.
Plants more resistant to drought, cold and harsh
conditions
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b.
May provide better protection against acid
precipitation
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c.
Prevent accumulation of toxic metals
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d.
Speed germination of orchid seeds
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e. Provide better growth in poor soils
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f.
Present in early fossil plants
FUNGAL RELATIVES
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A.
Lichens
1.
a.
b.
General Characteristics
Mostly ascomycetes with green alga and/or cyanobacterium
Specialized hyphae penetrate or envelop photosynthetic
c.
d.
Fungal chemical signals direct photosynthetic metabolism
Could be considered a form of controlled parasitism
cells
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a.
2.
Reproduction
Via normal fungal sexual processes
b.
Photosynthetic cell reproduction generally asexual
c.
Asexual reproduction by fragmentation
• 3. Ecology
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a. Inhabit cold, dry, generally harsh environments
b. Help break rock surfaces and prepare habitat for
other organisms
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c. Lichens with cyanobacteria can fix atmospheric
nitrogen
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d. Survive adverse conditions by nearly halting
metabolism
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e. First growth on barren rock-leads to soil
• 4. Lichens and Pollution
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a. Extremely sensitive to atmospheric pollutants
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b. Absorb substances dissolved in rain or dew
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c. Sensitive to sulfur dioxide an automobile
pollutant
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d. Indicates radioactive pollution