Question

Rice blast is caused by
(a)Taphrina deformis
(b)Puccinia graminis
(c)Magnaporthe grisea
(d)Colletotrichum falcatum

Answer 1

Hint: It is a fungal disease belonging to class Ascomycetes. Initial symptoms include white to gray-green lesions or spots, with dark green borders. It is also called blight disease. It is a plant-pathogenic disease.

Complete answer:
Magnaporthe grisea is the causative organism of the disease rice blast or rice blight. It is a fungus belonging to the class Ascomycetes. It is a plant-pathogenic fungus causing serious disease affecting rice. They also affect agriculturally important cereals including wheat, rye, barley, and pearl millet.

Additional Information: -Rice blast is a fungal disease. The fungi belongs to the class Ascomycete. Ascomycetes can reproduce by both sexual and asexual means.
-They basically infect the root tissues. The pathogen infects as a spore that produces spots on parts of the rice plant. The pathogen is invasive and moves to different parts too.
-Rice blast is significant in temperate regions and areas with irrigated lowland and upland.
-Excessive use of nitrogen also makes the plant susceptible to this fungal disease.
Taphrina deformis- It is also a fungus belonging to class Ascomycetes but it infects peach trees and causes peach leaf curl.
Puccinia graminis- It is a fungus belonging to the class Basidiomycetes and very commonly is known for stem rust disease. Black rust and cereal rusts are other diseases caused by these fungi.
Colletotrichum falcatum- It is also a fungus belonging to the class Ascomycetes. They are known as symbionts to plants. Many of them are plant pathogens but some may have mutualistic relationships
So, the correct answer is` Magnaporthe grisea`.

Note: Ascomycetes reproduces sexually as well as asexually. Fungi have a dikaryon stage in their life cycle where the haploid spores fuse together but the zygote is not produced immediately rather a fused stage is achieved.