Ooomycota

Outline

Heterokonts -- a new kingdom?

Properties

two different flagella

• whiplash
• tinsel (with characteristic 3-part mastigonemes)

mitochondria with tubular cristae

Taxonomy -- includes phyla:

Oomycota (water molds)

Chrysophyta (golden-brown algae)

(Xanthophyta [yellow-green algae])

Bacillariophyta (diatoms)

Phaeophyta (brown algae)

...and some protozoans (the Bicocoecids, in case you're interested, which include such genera as Cafeteria and Pseudobodo [no, I'm not making this up])

Properties of the oomycetes (water molds)

flagellated zoopores (heterokont, with whiplash and tinsel flagella)

mitochondria with tubular cristae

cellulose in cell walls

diplontic life cycle

oogamous sexual reproduction

oogamy vs. isogamy vs. anisogamy

Saprolegniales -- e.g., Saprolegnia

Ecology

freshwater

saprobic (also parasitic on fish eggs)

Morphology

mycelium is composed of coenocytic hyphae

Life cycle

asexual reproduction -- zoospores

sexual reproduction

diplohaplontic

oogonia and antheridia secrete hormones

Economic importance

Peronosporales -- e.g., Albugo

Ecology

terrestrial

plant parasites

Morphology

hyphae infest plant tissues

produce haustoria

Life cycle

also diplohaplontic

zoospores are released in sporangia

Economic importance

Phytophthora infestans caused the potato blight

Plasmopora causes downy mildew in grape vines

Vocabulary

click here to go to oomycete vocabulary