Reproduction in the chytridiomycota and related taxa

Fungi  in the  Chytridiomycota and  related groups are  quite distinct from  other fungi  as they  have  extremely simple thalli  and  motile zoospores. Some species within this group can be so simple that they consist of a single vegetative cell within (endobiotic) or upon (epibiotic) a host cell, the whole of which is converted into a sporangium, a structure containing spores. These types are termed holocarpic forms.

Other members of this group have a more complex morphology, and have rhizoids and a simple mycelium. Asexual reproduction in the Chytridiomycota is by the production of motile zoospores in sporangia that are delimited from the vegetative mycelium by complete septae. The zoospores have a single, posterior flagellum. Sexual reproduction occurs in some members of the Chytridiomycota by the production of diploid spores after either somatic fusion of haploid cells, or fusion of two different mating-type mycelia, or fusion of two motile gametes, or fusion of one motile gamete with a nonmotile egg. The resulting spore may undergo meiosis to produce a haploid mycelium or it may germinate to produce a diploid vegetative mycelium, which can undergo asexual reproduction by the production of diploid zoospores. The diploid mycelium can also produce resting sporangia in which meiosis occurs generating haploid zoospores that germinate to produce haploid vegetative mycelium.

                                                                   Figure:  Chytrid life cycle.