Molds
Phylum Mucoromycota
This contains many of the bread molds (e.g. Mucor), fruit mold (Rhizopus stolonifer), as well as root endophytes and plant decomposers. This group was formerly called the Zygomycota.
Ecology and Form
Mostly saprotrophic (feed on dead & decaying material)
No motile cells
Siphonous or coenocytic (long tubes without cross-walls)
Diversity
About 1,000 species; e.g. Rhizopus
Above: Rhizopus infecting a tomato
Above: Rhizopus infecting sweet potato
Above: mucoromycete with sporangia
Above: Dry Head Rot of sunflowers, caused by Rhizopus
Life Cycle
Reproduce asexually, or sexually through a haplontic life cycle
Sexual reproduction begins with gametangia on different strands (hyphae) fusing cytoplasm, mixing organelles but nuclei do not fuse (plasmogamy)
This is a form of conjugation.
Nuclei fuse (=karogamy) to produce a diploid spore case (=zygo-sporangium)
Zygosporangium goes through meiosis to produce haploid spore case (sporangia) on stalks.
Sporangia produce haploid spores for dispersal.
Spores germinate into new "body" (=mycelium)
Geologic Age
Ordovician - present
Questions for Thought
How are mucoromycetes similar to the chytrids?
How is the life-cycle of a mucoromycetes similar to the club or sac fungi