Kingdom Fungi-Introduction
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This is a very diverse group of organisms that includes yeasts, molds, rusts, and smuts.
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Fungi lack chlorophyll and do not carry on photosynthesis.
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Most are saprobes , although some are parasitic .

Kingdom Fungi-Intro.continued
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Saprobes (shown here), release digestive enzymes that break down food.
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Nutrients are then absorbed into the fungal cells.
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Parasitic fungi obtain their nutrients directly from their hosts.

General Fungi Characteristics
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Consist of threadlike filaments called hyphae .
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Hyphae grow in a tangled mass to form the mycelium .
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The hyphae are made up of cells containing the cytoplasm.

General Characteristics continued
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Fungal cells may or may not have cross walls (partitions).
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Cells with cross walls are called septate .
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Fungal cells may be multinucleate.
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Cell walls are made up of chitin
(a polysaccharide)
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Reproduction is both asexual and sexual by means of spores.
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80 000 species exist.

The Five Groups of Fungi

The fungi are divided into 5 groups based on their mode of reproduction:
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Group 1: Phylum Zygomycota.

Known as the zygomycetes .

Both sexual and asexual reproduction exist.

Hyphae lack crosswalls. But crosswalls do form during gamete production.

Most are saprobes and some are parasitic.

Bread Mold Rhizopus sp.

Bread Mold Gone Bad !

Phylum Zygomycota

Sexual Reproduction in Rhizopus

Group 2 Phylum Oomycota

Phylum Oomycota

The Water molds

Most are saprobes and some are parasites on fish.

Some are plant parasites such as the late blight fungus that caused the Irish Potato Famine
(1845-1847).
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Only group with motile flagellated spores.

Only group with structurally different male and female gametes (sperm and eggs).

Phylum Oomycota continued

Cell walls made of cellulose and not chitin.

Hyphae have no cross walls.
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Diploid stage is dominant in their life cycle.

Group 3 Phylum Ascomycota

Largest known group.

Multicellular

Hyphae have cross walls.

Sac fungi form two types of spores:

Sexual Spore -produces in a sac-like structure called the ascus . 8 ascospores per ascus.

Asexual Spore -Produced at the tip of specialized hyphae called conidiophores.
The spores are called conidia .

Ergotism-An Ascomycete
Disease.

Disease caused by the plant parasite,
Claviceps purpurea .

Grows on rye.
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Bread made with contaminated rye, causes severe illness in humans.

Ergotism continued
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Symptoms include gangrene, nervous spasms and convulsions.
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Ergot is used in medicine to cause blood vessels to constrict.
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It is the initial source of the psychedelic drug
LSD.

Group 4 Phylum-Basidiomycota

Phylum Basidiomycota

The club fungi.

Spores form in a club-shaped structure called the basidium .

The spores are called basidiospores .
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Hyphae are divided by incomplete crosswalls.
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Cells have two nuclei.

Group 5 Imperfect Fungi

These molds do not fit into the other groups of fungi, as they lack sexual stages in their life cycles and hence are said to be imperfect.
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Reproduction is asexual by way of spores.
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Some are predatory and trap protists and small round worms.

Predatory Fungus

A Captured Nematode

Mycorrhizae
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Many fungi form symbiotic associations with the roots of green plants, by way of mycorrhizae (“fungusroots”).
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Some of these fungi form distinct layers on the outside of roots (ecto-mycorrhizae), while others are deep in the roots.

Mycorrhizae

The fungi get sugars from the plant host.
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The plant itself gets nutrients from the fungi, including nitrogen and phosphorous.
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The mycorrhizae also protect plants from heavy metals by acting as filters.

The Lichens
Lichens are formed when certain algae join with certain fungi .
Mr. Algae
Mr. Fungus

Lichens-A Symbiotic
Relationship
Together, the algae and the fungus form a living unit.
What we have here is a symbiosis.
The algae through photosynthesis produce sugar as a food source, and the fungus provides support and protection from drying.

General Structure of a Lichen

Foliose lichen – resembles lettuce.

Crustose Lichen – Fairy barf

Fruticose lichen-Old Man’s Beard

Microscopic View of a Lichen