Question

Which of the following is NOT a feature of Oomycetes plant pathogens?

• A. Motile spores
• B. Coloured spores
• C. Hyaline mycelium
• D. Coenocytic mycelium

Hint:

Remember that Oomycetes are water molds, which thrive in wet conditions.
Their characteristic asexual spore is the colorless, swimming zoospore, which relies on aquatic motility rather than pigmented pigments for survival.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Oomycetes (commonly known as water molds) are eukaryotic microorganisms that belong to the kingdom Stramenopila rather than the kingdom Fungi.
They are phylogenetically distinct from true fungi, possessing cellulose-based cell walls instead of chitin, and displaying diploid vegetative states.

Step 2: Detailed Explanation:
Oomycete pathogens, such as Phytophthora and Pythium, exhibit specific cytological and reproductive characteristics.
They produce coenocytic (non-septate) mycelium, which is transparent and lacks melanin or other significant pigmentation, giving it a hyaline appearance under the microscope.
This confirms that "Hyaline mycelium" and "Coenocytic mycelium" are typical features of Oomycetes.
During asexual reproduction, Oomycetes release biflagellate zoospores that are highly motile in free water, making "Motile spores" a key characteristic.
These motile zoospores navigate toward host plants using chemotaxis and electrotaxis.
Unlike true fungi, which frequently produce colored spores (such as black, green, or brown conidia containing pigments like melanin), Oomycete asexual spores (sporangia and zoospores) are typically hyaline or colorless.
Therefore, "Coloured spores" is not a standard feature associated with Oomycete plant pathogens.

Step 3: Final Answer:
Coloured spores is NOT a feature of Oomycetes plant pathogens.