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

Geologic Age

Mesoproterozoic (~1.5 billion years ago) - present
- Macro-fossils from the Devonian
- Most ancestral true fungi

Classification

Unikonta

└Opisthokonta

└Fungi

└Chytridiomycota

Diversity

~790 spp. e.g., Synchytrium, Batrachochytrium

Symbioses

Decomposers and plant pathogens
- Brown spot (corn)
- Crown wart (alfalfa)
- Black wart/black scab (potato)
Chytrids feed on plant material in aquatic environments (e.g., pollen and spores in ponds)

Chytridiomycosis

They are well known for causing a skin disease on amphibians when their zoospores infect the skin of frogs.
This disease leads to the death of many species and decimates amphibian populations worldwide.
See images at bottom

Right: Black wart (Synchytrium endobioticum) in potato

Far right: Brown spot (Physoderma maydi)

Questions for Thought

How are the chytrids similar to the mucuromycetes?
How are chytrids similar to the slime molds?

Additional Resources

A fungus that kills toxic algae threatening human health (Phys.org 17Dec2025)

└Algophthora mediterranea, gen. et sp. nov.: Novel dinoflagellate- and diatom-infecting generalist marine chytrid from the Mediterranean Sea (Pou-Solà et al., 2025)

Endangered frogs fight back: Deadly fungus spurs breeding increase (Phys.org 28May2025)

└Brannelly et al. (2025) Devastating disease can cause increased breeding effort and success that improves population resilience

Die off of frogs maybe caused by chytrids (AMPHIBIAWEB)

Google Sites

Report abuse