Fungi – Chapter 31
Defining Fungi
Fungi share the following characteristics
1. Heterotrophs that absorb nutrients – External Digestion
2. Cell walls that include chitin
3. Some have a dikaryon stage
4. Undergo nuclear mitosis
5. Zygotic life cycle (except Chytrids)
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General Biology of the Fungi
General Biology of the Fungi
Multicellular fungi consist of long, slender filaments
called hyphae
A mass of connected hyphae is called a mycelium
-It grows through and digests its substrate
-Some hyphae
are continuous
-Others are
divided by septa
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General Biology of the Fungi
General Biology of the Fungi
Monokaryotic
Asexual reproduction
Asexual spores Æ Haploid cells
Dikaryotic
Heterokaryotic
Sexual reproduction
Æ Fusion of two haploid hyphae of compatible mating
types
Æ In some fungi, fusion immediately results in a diploid
(2n) cell
Æ Others, have a dikaryotic stage (1n + 1n) before parental
nuclei form diploid nucleus
Genetic diversity of fungal hyphae
-Monokaryotic – One nucleus
-Dikaryotic – Two nuclei
-Heterokaryotic – Nuclei from genetically distinct individuals
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Phylogenetic Relationships of Fungi
Deuteromycota
Five major fungal phyla – 1.5 million species
Aquatic
flagellated
fungi
Zygote
fungi
Mycorrhizal
fungi
Imperfect fungi - a polyphyletic group
-15,000 species
-No sexual reproductive stage has been observed
-Many appear to be related to the ascomycetes
Sac
fungi
Club
fungi
-Penicillium
-Penicillin
-Blue cheeses
-Aspergillus
-Soy sauce
-Soy paste
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Zygomycota – Zygote Fungi
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Ascomycota
Phylum Ascomycota – Sac fungi
75% of the known fungi
Formation of Ascus in an Ascocarp
Include bread yeasts, common molds,many serious
plant pathogens, cup fungi and morels
1050 Species
Black bread mold
Some human pathogens
No septa in hypha
Asexual reproduction
sporangia on sporangiophores
Sexual reproduction
Compatible hyphae fuse
Zygosporangium formation
Karyogamy
Meiosis
Germinating zygosporangium
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Ascomycota
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Basidiomycota – Club Fungi
Phylum Basidiomycota – club fungi
-Mushrooms, puffballs, jelly fungi
-Plant pathogens such as rusts and smuts
Asexual Reproduction
Conidium = asexual haploid spore
Club-shaped basidium
Karyogamy occurs within basidia
Meiosis follows
Basidiospores borne externally
Fruiting body = basidiocarp
Sexual Reproduction
Extended dikaryotic hyphal stage
Saclike ascus forms within the ascocarp
Karyogamy, meiosis & mitosis occurs
within the ascus
8 haploid nuclei become ascospores
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Ecology of Fungi
Fungal Parasites and Pathogens
1. Principal decomposers in the biosphere
break down cellulose and lignin
Fungi also cause human and animal diseases
-Candida – Thrush; vaginal infections
-Pneumocystis jiroveci – Pneumonia
-Athlete’s foot and nail fungus
2. Symbioses
Lichens are symbiotic associations
3. Mycorrhizae
Fungi live with plant roots
Fungal diseases are difficult to treat because of the
close phylogenetic relationship between fungi and
animals
4. Pathogens & parasites
benefit at the expense of their host
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Fungal metabolites
Fungal Plant Parasites
amanitin
Claviceps causes ergot in rye
1. Convulsive ergotism
St. Anthony’s fire
2. Ergotate
Amanita caesarea
Amanita phalloides
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Fungi – Psychoactive metabolites
END Fungi
• 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
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