Zygomycota

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

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.

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

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

columella sporangium sporangiophore rhizoids Rhizopus

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

Sexual Reproduction - + Mycelium Progametangia karyogamy Zygospore Suspensors Zygospore Zygote karyogamy

Zygomycota Life Cycle

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

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)

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

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.

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

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