Question

Which of the following diseases is caused by Mycoplasma?
A. Citrus greening
B. Sandal spike
C. Grassy shoot of sugarcane
D. All of the above

Answer 1

Hint: Mycoplasma belongs to the genus of bacteria and they lack a cell wall around the plasma membrane, because of which they are naturally resistant to antibiotics.

Complete Answer:
Mycoplasma is a genus of bacteria which causes diseases in humans, animals and plants.

- Citrus greening is a disease of citrus plants and is caused by Mycoplasmas. The symptoms of this disease include - yellow shoots, twig dieback, fruits remain green even after ripening.
- Sandal spike is caused by Mycoplasma and the trees which are infected die within 1-2 years of visible symptoms. The disease is characterised by extreme reduction in leaf size, reduction of internode length and once advanced the entire shoot gives an appearance of spike inflorescence.
- Grassy shoot of sugarcane is a disease found in sugarcane and is caused by small and parasitic mycoplasma. This disease leads to losses of 5% to 20% of yield loss of sugarcane. The symptoms of this disease are - whitening or yellowing of the leaves, shortening of the internodes, loss of apical dominance, etc.

Thus, the correct option is D) All of the above.

Note: Mycoplasma belongs to kingdom Monera, and its characteristics are,
- They are very small in size (150-250nm).
- They are prokaryotes but do not have a cell wall.
- They have a special cell membrane which contains steroids, which is not present in either bacteria or viruses.
- They are seen as fried-egg colonies on agar.