L3 oomycetes Flashcards
(34 cards)
What is the superphylum that includes Oomycota?
Stramenopiles (Heterokonta)
What are the two flagella types in Oomycota zoospores?
Tinsel flagellum (pulls forward) and whiplash flagellum (pushes backward)
How do Oomycota reproduce asexually?
Through sporangia, resting spores, and/or zoosporangia producing biflagellate zoospores.
What type of hyphae do Oomycota have?
Coenocytic (non-septate) diploid hyphae.
Name a significant disease caused by Oomycota in fish.
Saprolegniosis (caused by Saprolegnia parasitica).
What is the ecological role of Oomycota?
They can be saprophytes, parasites, or pathogens affecting animals and plants
Which order of Oomycota is known for causing Downy Mildew?
Peronosporales (specifically Plasmopara viticola).
Describe the sexual reproduction process in Saprolegniales.
Formation of compatible oogonia and antheridia on the same mycelium, leading to fertilization and oospore development.
What are the conditions that favor the development of Downy Mildew?
Cool and damp conditions.
How do Hyphochytriomycota differ from Chytridiomycota in flagella structure?
Hyphochytriomycota have a single tinsel flagellum, while Chytridiomycota have a single posterior whiplash flagellum.
What are common habitats for Hyphochytriomycota?
Freshwater, marine environments, and soil.
What is the significance of Phytophthora infestans in history?
It caused the Irish potato famine in 1845.
How are zoospores of Oomycota dispersed?
Motile zoospores swim through water before encysting and germinating.
What does the term “oogamous” refer to in Oomycota reproduction?
The presence of non-motile female gametes that are larger than male gametes.
How many phyla are identified within the superphylum Stramenopiles?
Two phyla: Oomycota and Hyphochytriomycota.
What types of organisms are found in the Phylum Oomycota?
Water molds, including saprophytes, parasites, and pathogens
Describe the structure of Oomycota cell walls.
Made of cellulose and glucans.
What type of reproduction is predominant in Oomycota?
Asexual reproduction is predominant, but sexual reproduction also occurs
What are the two reproductive strategies in Oomycota?
Homothallic (same mycelium) and heterothallic (different mycelia).
How do motile zoospores of Oomycota differ in structure?
The tinsel flagellum has lateral branches (mastigonemes), while the whiplash flagellum is smooth.
What is the impact of Saprolegnia parasitica on fish?
It can cause skin lesions, lethargy, and can lead to mortality in infected fish.
What environmental factors increase susceptibility to Saprolegniosis in fish?
High population density, temperature extremes, and stress from other infections.
How do Pythium species affect crops?
They cause root rot and damping-off in many plant species.
What is a defining characteristic of the Order Peronosporales?
Most are obligate parasites on the aerial parts of higher plants.
