Classification of Fungi
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Biologists use fungal structure and methods of reproduction to divide fungi
into four major phyla:
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Chytridiomycota (chytrids)
Zygomycota (common molds)
Ascomycota (sac fungi)
Basidiomycota (club fungi)
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Diversity of Fungi
Chytrids
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Chytrids are members of phylum Chytridiomycota
Saprophytes and parasites
Mostly aquatic
Produce flagellated spores
May be evolutionary link between fungi and funguslike protists
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Diversity of Fungi
Common Molds
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Common molds belong to the phylum Zygomycota.
Mostly terrestrial
Some are in mutualistic relationships with plants
Form specialized hyphae called stolons, which grow across the surface of
food.
Also have rhizoids, hyphae which penetrate into food and absorb nutrients
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Diversity of Fungi
Common Molds
Life cycle
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Reproduce both sexually and asexually
Asexual reproduction involves sporangia producing haploid spores.
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Diversity of Fungi
Common Molds
Life cycle
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Sexual reproduction occurs when the environment is no longer favorable.
No defined male and female fungi, just (+) and (-) mating strains
Hyphae produce gametangia, reproductive structures that contain haploid
nuclei.
Zygotes can remain dormant for months until the environment becomes
favorable.
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Diversity of Fungi
Sac Fungi
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Sac fungi belong to phylum Ascomycota.
Contains more species than any other phylum of fungi
Most sac fungi are multicellular, although it also includes unicellular groups
(yeasts).
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Diversity of Fungi
Sac Fungi
Life cycle
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Reproduce sexually and asexually
During asexual reproduction, spores are formed at the tips of hyphae called
conidiophores.
Spores are dispersed by wind, water, or animals.
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Diversity of Fungi
Sac Fungi
Life cycle
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During sexual reproduction, hyphae from opposite mating types fuse and
one nucleus from each pairs off in separate cells.
Hyphae develop into reproductive structures called ascocarps.
Haploid cells fuse in the ascocarp to form a zygote, which divides into spores
in a structure called the ascus, which produces ascospores.
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Diversity of Fungi
Club Fungi
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Members of the phylum Basidiomycota
Contain the mushrooms
Can be saprophytic, parasitic, or mutualistic
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Diversity of Fungi
Club Fungi
Life cycle
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Rarely produce asexual spores
Spend most of their life cycle as dikaryotic mycelia, meaning each cell has
two nuclei
Periodically reproduce sexually by forming basidiocarps, a type of fruiting
body
• Grow rapidly through cell enlargement
• Composed of basidia, club shaped hyphae that produce spores
• Release haploid basidiospores
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Diversity of Fungi
Other Fungi
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Organisms in phylum Deuteromycota share only one unique trait – sexual
reproduction has never been observed.
Referred to as imperfect fungi
Modern genetic techniques may reclassify these fungi into one of the four
major phyla.
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Diversity of Fungi
Review
Essential Questions
• What are the four major phyla of fungi?
• What are the distinguishing traits of each fungus phylum?
• What are the reproductive strategies of each fungus phylum?
Vocabulary
• stolon
• rhizoid
• gametangium
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• conidiophore
• ascocarp
• ascus
• basidiocarp
• basidium
• basidiospore
Diversity of Fungi