Question

Choose the correct option about Magnaporthe
A. Magnaporthe affects only monocots
B. Magnaporthe affects only dicots
C. Magnaporthe is seed-borne
D. Magnaporthe is non motile

• A. (A), (B) and (D) only.
• B. (A), (B) and (C) only.
• C. (A), (B), (C) and (D).
• D. (A), (C) and (D) only.

Hint:

Remember that blast disease primarily targets cereals (monocots) and is successfully transmitted through contaminated seeds.
Ascomycete spores are always non-motile, unlike Oomycete zoospores.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Magnaporthe (specifically Magnaporthe oryzae, with its asexual stage Pyricularia oryzae) is the ascomycete fungus responsible for rice blast, one of the most destructive diseases of cereal crops.

Step 2: Detailed Explanation:
Let us analyze each statement individually:
Statement A and B: Magnaporthe is specialized to infect plants belonging to the family Poaceae (Gramineae), which are monocotyledonous.
It causes blast disease in crops like rice, wheat, barley, finger millet, and various wild grasses.
It does not infect dicotyledonous plants.
Thus, Statement A is true, and Statement B is false.
Statement C: Magnaporthe is well-documented to be a seed-borne pathogen.
The fungus survives as dormant mycelium or conidia within or on the surface of seeds.
Sowing infected seeds allows the pathogen to establish early-season infections, making control difficult.
Thus, Statement C is true.
Statement D: As an ascomycete fungus, Magnaporthe does not produce any flagellated, swimming cells.
Its asexual spores (conidia) are dispersed passively by wind, dew droplets, and water splashes, meaning they are completely non-motile.
Thus, Statement D is true.
Therefore, the correct combination of statements is (A), (C), and (D).

Step 3: Final Answer:
The correct option is (A), (C) and (D) only.