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Zygomycota

Zygomycota. General characteristics. Hyphae are coenocytic Flagellated spores are absent Most reproduce asexually by producing sporangiospores within a special sac called the sporangium .

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Zygomycota

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  1. Zygomycota

  2. General characteristics • Hyphae are coenocytic • Flagellated spores are absent • Most reproduce asexually by producing sporangiospores within a special sac called the sporangium. • Sexual spores are called zygospores contained within a zygosporangium formed following gametangial fusion / copulation

  3. Classification • Two classes:Zygomycetes and • Trichomycetes. • Zygomycetes • 870 species in 124 genera, 32 families and 10 orders. • Trichomycetes • 218 species in 55 genera, 6 families and 3 orders.

  4. Class: zygomycete. order mucorales Family Family Mucoraceae Mortierellaceae Family Family Thamnidiaceae Chaenophoraceae Family Family Pilobolaceae Cephalidaceae

  5. Asexual reproduction • Reproduce asexually by sporangiospores in most orders of the Zygomycetes, conidia in the Entomophthorales and arthrospores in some Trichomycetes • Sporangium types (4 types) • True sporangium • Sporangioles - much smaller than true sporangia.  No columella produced and few spores (1-50) • Monosporous sporangium (one-spored sporangium) • Merosporangium - sac containing 10 -15 sporangiospores that occur in a linear sequence

  6. columella sporangium sporangiophore rhizoids Rhizopus

  7. Sexual Reproduction • Gametangial copulation • Homo- & heterothallic species • Heterothallism the condition of being self-sterile, requiring a partner for sexual reproduction • Homothallism the condition of being self fertile; able to reproduce sexually without a partner  exhibited among species in this phylum • zygos (Gr.) - yoke, joining • Refers to the fusion of gametangia to form a unique structure called the zygosporangium • Zygosporangium • gametangium

  8. Sexual Reproduction Suspensors Gametangia Zygote Zygospore + - Mycelium Progametangia karyogamy

  9. Zygomycota Life Cycle

  10. 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

  11. Mucorales • Members of this group are the "weeds" of the fungal world • Common genera include Mucor, Absidia,Rhizopus, and Pilobolus. • Grow and invade quickly on easily digestible substrates, such as those containing starches, sugars, and hemicelluloses • Can act as parasites and/or cause diseases in plants, animals and some insects and humans • In humans, such diseases are opportunistic and occur in an immunocompromised person (e.g., uncontrolled diabetes, AIDS)

  12. Order Mucorales: Body plan • rhizoids: root-like hyphae that adhere reproductive structures to substrate • stolon: connect two groups of rhizoids

  13. Classification of mucorales Mucorales is divided into the following families: 1- Mucoraceae: sporangia always present, columellae present, zygospor usually naked; wall of the sporangium homogenous, not cuticularized, usually diffluent, sporangia of one sort. 2- Thamnidiaceae: sporangia of two – sorts, primary and secondary. e.g. Thamnidium sp.

  14. 3- Pilobolaceae: wall cuticularized and persistent above,thin and diffluent below. E.g. pilobolus sp.

  15. 4- Mortierellaceae: columella absent; zygospore enveloped in a dense hyphal covering. E.g. mortierelle sp.

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