Reproduction in the Zygomycota

In the Zygomycota, asexual reproduction begins with the production of aerial hyphae. The tip of an aerial hypha, now called a sporangiophore is separated from the vegetative hyphae by a complete septum called a columella. The cytoplasmic contents of the tip differentiate into a sporangium containing many asexual spores. The spores contain haploid nuclei derived from repeated mitotic divisions of a nucleus from the vegetative mycelium. Dispersal of the spores is by wind or water.

In sexual reproduction, two nuclei of different mating types fuse together within a specialized cell called a zygospore. In some species the different mating-type nuclei may be within one mycelium (homothallism). In other species, two mycelia with different mating-type nuclei must fuse (heterothallism). In both cases, fusion occurs between modified hyphal tips called progametangia, which once fused are termed the zygospore. Within the developing zygospore meiosis occurs; usually three of the nuclear products degenerate, leaving only one nuclear type present in the germinating mycelium.

                                                   Figure. Life cycle of a typical zygomycete.