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

Mucoraceae

Family

Thamnidiaceae

Family

Pilobolaceae

Family

Cephalidaceae

Family

Chaenophoraceae

Family

Mortierellaceae

Family

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

Rhizopus

sporangiumcolumella

sporangiophore

rhizoids

•gametangium

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

ProgametangiaMycelium

+ -

Gametangia

Suspensors

ZygoteZygosporeka

ryo

gam

y

Sexual Reproduction

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.