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Phylum Zygomycota

Phylum Zygomycota. Pl P 421/521. Classes. Zygomycetes 870 species in 124 genera, 32 families and 10 orders Trichomycetes 218 species in 55 genera, 6 families and 3 orders. Based on 18S + 28S + 5.8S. Zygomycetes. Trichomycetes. From White et al. 2006. Mycologia 98:872-884.

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Phylum Zygomycota

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  1. Phylum Zygomycota Pl P 421/521

  2. Classes • Zygomycetes • 870 species in 124 genera, 32 families and 10 orders • Trichomycetes • 218 species in 55 genera, 6 families and 3 orders

  3. Based on 18S + 28S + 5.8S Zygomycetes Trichomycetes From White et al. 2006. Mycologia 98:872-884

  4. Sexual Reproduction • Sexual reproduction by production of zygospores (=thick-walled resting spores) within zygosporangia that are formed by fusion of gametangia

  5. + - Mycelium Progametangia Suspensors karyogamy Gametangia Zygote Zygospore plasmogamy

  6. http://www.botany.utoronto.ca/ResearchLabs/MallochLab/Malloch/Moulds/Zygospores_of_Mucorales.htmlhttp://www.botany.utoronto.ca/ResearchLabs/MallochLab/Malloch/Moulds/Zygospores_of_Mucorales.html

  7. Asexual Reproduction • Sporangia • Sporangiospores delimited from cytoplasm by cleavage vesicle fusion • Conidia • Formed by same mechanism as blastoconidia

  8. Sexual Compatibility • Regulated by trisporic acid, a sex pheromone (Blakeslee, 1904): • Enhances secretion of specific precursors of trisporic acid and beta-carotene • Positively regulates its own synthesis by stimulating rate of precursor formation in paired cultures • Induces zygophore formation • Represses sporangiophore formation

  9. Zygospores • Thick-walled, usually hyaline, but zygosporangium wall often pigmented and ornamented • One zygospore per zygosporangium • Germination by formation of hyphae or sporangium

  10. Class Zygomycetes • Classification: • Mucorales • Mortierellales • Kickxellales • Dimargaritales • Zoopagales • Entomophthorales • Endogonales

  11. Order Mucorales • 30% of known zygomycetes (~300 spp.) • Well developed, typically coenocytic mycelium • Wall composition of chitosan, chitin and polyglucoronic acid • Asexual reproduction by formation of sporangiospores cleaved out from the cytoplasm of sporangia • Chlamydospores may be formed • Called mucoralean or mucoraceous fungi

  12. Sporangia • Most taxa produce globose sporangia • Sporangial wall can be persistant or fragile, of various colors, and is usually smooth

  13. Mucor sporangiospores columella sporangium sporangiophore http://www.botany.utoronto.ca/ResearchLabs/MallochLab/Malloch/Moulds.html

  14. Sporangia • Apophysate • Subsporangial swelling • Nonapophysate • Lacking subsporangial swelling

  15. Sporangiospores • One-celled • 1- to multinucleate • Smooth-walled, or ornamented with spines, warts or striations • Most taxa produce hyaline spores • Some taxa produce spores with hyaline appendages

  16. Sporangiolum • Sporangium containing 1-50 spores • Merosporangium is a sporangiolum with spores in linear series

  17. Rhizopus stolons rhizoids http://www.botany.utoronto.ca/ResearchLabs/MallochLab/Malloch/Moulds.html

  18. Rhizopus From Bioimages

  19. Pilobolus • Common fungus sporulating on dung • Sporangia with dark, thick, persistant wall • Characterized by forcibly discharged sporangia (> 2 meters!) • Sporangiophores are phototropic (bend towards light) • Pilaira—similar morphology and ecology, lacks discharge mechanism

  20. sporangium sporangiophore trophocyst substrate

  21. Photo by Marco Hernandez-Bello

  22. Photo by Marco Hernandez-Bello

  23. Ecology • Saprotrophs • Soil, dung, humus • Plant pathogens • Choanephora cucurbitarium • on flowers & fruits of cucurbits • Rhizopus stolonifer • Post-harvest pathogen of strawberries, sweet potatoes • Animal pathogens • Species of Absidia, Mucor, Rhizopus, Saksanea

  24. Industrial applications • Industrial production of amylases, rennins, secondary metabolites and organic acids • citric, fumaric, lactic and succinic acids

  25. Production of Asian Foods • Tofu or sufu (Chinese cheese) • A soft cheese-type product made from cubes of soybean curd using fermentation by Actinomucor elegans • Tempeh • A solid cakelike product from soybeans fermented with Rhizopusoligosporus

  26. Order Mortierellales • 10% of known zygomycetes (~100 spp.) • Characterized by thin, delicate, “arachnoid-like” mycelium, zonate colonies and garlic-like odor • Sporangiophores either acolumellate, or with rudimentary columella • Often form chlamydospores

  27. No columella Mortierella http://www.botany.utoronto.ca/ResearchLabs/MallochLab/Malloch/Moulds.html

  28. Order Kickxellales • One family and eight genera • Characterized by one-spored sporangiola formed on pseudophialides borne on sporocladia • Extensively branched, septate mycelium • Saprotrophs, common in soil and dung

  29. pseudophialides merosporangia sporocladia From O’Donnell 1979

  30. From O’Donnell 1979

  31. Order Dimargaritales • One family and four genera • Characterized by 2-spored merosporangia formed on terminal inflated ampullae • Produce branched, septate hyphae with unusual, dumbbell-shaped septal plugs • Obligate mycoparasites of mucoraceous fungi

  32. Dimargaris From O’Donnell 1979

  33. Order Zoopagales • Five families, 21 genera, 163 species • Coenocytic or septate hyphae • Conidia or multispored merosporangia • All members are obligate parasites of other fungi or microscopic animals (amoebae, rotifers, nematodes) • Ectoparasitic, endoparasitic or predaceous • Haustoria formed in host in ectoparasitic and predaceous species

  34. Syncephalis (11) and Piptocephalis (12) From O’Donnell 1979

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