L3 oomycetes Flashcards
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.
What was one of the world’s first fungicides developed for?
The control of Plasmopara viticola (Downy Mildew).
How does Phytophthora ramorum affect plants?
It causes Sudden Oak Death and affects over 100 plant species.
What is the life cycle of Phytophthora infestans characterized by?
A heterothallic sexual stage requiring compatible mycelia for oospore formation.
How are zoospores of Hyphochytriomycota characterized?
They release uniflagellate zoospores with a single tinsel flagellum.
What is a common host for Hyphochytriomycota?
They can be hyperparasites on oospores of other Oomycetes and can colonize plant pollen.
What are mastigonemes?
Lateral filaments on the tinsel flagellum of some zoospores
How can water molds be detected in the environment?
By isolating samples from water or infected fish tissue, using bait like hemp seeds for incubation.
What role does temperature play in the life cycles of Oomycota?
Cool and damp conditions favor disease development and zoospore swimming.
What type of spores do Oomycota form for survival?
Oospores, which are thick-walled and persistent.
How do the life cycles of Oomycota and Hyphochytriomycota differ?
Oomycota have well-documented asexual and sexual stages; Hyphochytriomycota’s sexual reproduction is less understood.
