Chytrids

Phylum Chytridiomycota

Chytrids are an ancestral group of fungi, that are mostly aquatic parasites or saprotrophs. They are known for causing plant diseases such as brown spot on corn, crown wart on alfalfa, and black scab on potatoes, which can be significant for farmers, particularly during rainy summers. This group is interesting, evolutionarily, since their parasitic nature and ancestral position in the fungus kingdom may indicate that the earliest fungi on Earth were aquatic and parasitic (and zoosporic), and later became terrestrial and saprotrophic, and eventually mutualistic with plants.

Ecology and Form

Usually siphonous or coenocytic (=tubes without cross walls)
Mostly aquatic and with zoospores (flagellated spores)
Parasites and saprotrophs

Life cycle

Chytrids exhibit a haplo-diplontic lifecycle, unlike other fungi
The sporophyte produce spore cases (sporangia) which create flagellated spores (zoospores) through meiosis
Zoospores are dispersed and germinate into gametophytes
Gametophytes mature to produce male and female sexual structures (gametangia)
Gametangia produce motile male and female gametes which fuse in the water to produce zygotes