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Classification of Fungi

Classification of Fungi. Fungi are more closely related to animals than plants:. Animals and fungi have flagellate cells Example: chytrid gametes and spores Propel themselves with single posterior flagellum Like animal cells, fungal cells have plate-like cristae in their mitochondria.

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Classification of Fungi

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  1. Classification of Fungi

  2. Fungi are more closely related to animals than plants: • Animals and fungi have flagellate cells • Example: chytrid gametes and spores • Propel themselves with single posterior flagellum • Like animal cells, fungal cells have plate-like cristae in theirmitochondria

  3. Classification • Historically classified by characteristics of sexual spores and fruiting bodies • More recently, molecular data • DNA • RNA • Currently, 5 phlya

  4. Fungal Evolution

  5. Phylum Chytridiomycota • Earliest fungal phlyum to diverge • Relatively simple; most unicellular • ONLY FUNGI with flagellated cells • Most have no sexual reproduction • Most decomposers; few cause disease

  6. Phylum Glomeromycota • Recently classified (2002) • Form symbiotic mycorrihizae • Coenocytic hyphae • No known sexual reproduction

  7. Phylum Zygomycota • Coenocytic hyphae • Ex: black bread mold (Rhizopus) • Most decomposers, some mycorrhizae, few disease

  8. Zygomycete Reproduction • Hyphae of 2 different mating types (+) and (-) come in contact with one another • Tips of hyphae form gametangia, fuse • Karyogamy  zygote (2n)

  9. Zygote develops into zygospore surrounded by zygosporangium • zygospores - undergoes meiosis, creating haploid spores • Zygospore germinates, develops aerial hyphae with sporangium at tip • Haploid spores produced through mitosis • May be all +, all -, or mix • http://www.wisc-online.com/objects/index_tj.asp?objID=BIO504

  10. Ascomycetes and Basidiomycetes are sister phyla

  11. Phylum Ascomycota • aka “sac fungi” or “cup fungi” • Includes yeasts, powdery mildews, molds • Hyphae with perforated septa • Asexual reproduction by conidiophores

  12. Sexual Reproduction in Ascomycetes • Opposite mating types produce coenocytic sexual hyphae • Hyphae fuse and nuclei migrate • Pairs of nuclei associate but do not fuse (n + n)

  13. New hyphae with dikaryotic cells develop and branch repeatedly • Sac-shaped asci develop; karyogamy occurs • Diploid zygote • Meiosis forms 4 haploid nuclei • Mitosis of each results in 8 haploid nuclei • Each haploid nucleus becomes enclosed in ascospore, released at tip of ascus

  14. Phylum Basidiomycota • aka “club fungi” • Mushrooms, bracket fungi, puffballs • Asexual reproduction less common

  15. Basidiomycete Sexual Reproduction • Hyphae of different mating types of primary mycelium come in contact and fuse • Form dikaryotic cell which develops into secondary mycelium • Under favorable conditions, form buttons along mycelium • Button develops into mushroom

  16. Karyogamy – zygote is only diploid stage • Meiosis forms 4 haploid nuclei • Nuclei move to outer edge of basidium, form extensions  basidiospore • Septum forms

  17. Key things to remember: • Chytrids – only flagellated fungi • Glomeromycetes – no sexual stage • Zygomycetes - gametangia • Ascomycetes – dikaryotic stage; produce 8 haploid spores in ascus • Basidiomycetes – dikaryotic stage; produce 4 haploid spores in basidia

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