Bio 332 lecture 8 Zygomycetes and Chytrids

The True Fungi

1. Basidiomycota

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2. Ascomycota

a. Deuteromycetes (Imperfects)

• I hyphomycetes

• II coelomycetes

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4\. Glomeromycota

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5\. Chytridiomycota

Taxonomy

Identification of an organism, giving it a name, matching names with creatures

Evolutionary Sythesis

Figuring out how organisms are related and their evolutionary paths

Taxonomy and Evolutionary Synthesis

Both fields are integrated but the **rise of DNA
technologies has sometimes significantly changed
taxonomy**


• In real life, organisms don’t precisely follow the
groups we use to make things convenient


• Phylogenies (dendrograms) are more accurate but
harder to visualize


• We know more today than we did 20 years ago and
will know still more in 20 year

The zygomycetes

considered paraphyletic.

A group composed of a collection of organisms, including the most recent common ancestor of all those organisms.



HOWEVER, unlike a monophyletic group, **a paraphyletic taxon does not include all the descendants of the most recent common ancestor.**

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Frankly, there is still a lot of disagreement on what constitutes the Zygomycetes

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We include them because they don’t produce zygomycetes stuff???

Glomeromycota (Zygomycota)

• Coenocytic(no septations in their cell) hyphae (unlike other true fungi)


• Produce zygospores (sexual resting structures)
and sporangia (with asexual sporangiospores)


• Chitosan instead of chitin


• Only a few plant pathogens


• Mostly cause post-harvest diseases or diseases
of soft berries


• Black bread mold


• Occasionally horticultural crops are infected


• Very important as mycorrhizal fungi

Glomeromycota (Zygomycota) sexual tages

Pilobolus

• Genus of Zygomycete


• Called the dung canon fungus


• Spores get eaten by herbivore, pass through the intestines of animal


• Germinate in animal dung


• Shoot the spores about 10 feet


• Acceleration of the spore subjects it to about 20,000 G’s!

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• Some parasitic nematodes climb up to the spore to get flung into the path of the herbivore

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Chytridiomycota

Commonly called chytrids

• Limited mycelium (rhizoids)

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• Have swimming zoospores (the only exception in the true fungi)(the only to have swimming zoospores)

• Only a few plant parasites

• Mostly decomposers in lakes and ponds

• Major amphibian parasite

• Obligate parasites in plants

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Two forms

• Synchytrium causes wart of potato;

• Olpidium transmits several viruses

Potato Wart; Synchytrium endobioticum

From the Andes, S. America but spread to England and Europe. In 2000, discovered in Prince Edward Island, Canada; resulting in $30 million losses to economy. 2019, discovered in Georgia, USA

Olpidium

a. Sporangia

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b. Empty sporangium

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c. Zoospores

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d. Encysted zoospores

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e. Resting sporangia

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Infection by the Chytrid is trivial but if it carries a virus it can significantly affect susceptible crops