Question

Given below are two statements:
Statement (I): Phytoplasmas are found in Phloem
Statement (II): Phytoplasmas are transmitted by beetles
In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

Phytoplasmas are wall-less, phloem-limited prokaryotes. Because they reside only in the phloem sap, they are transmitted by sap-sucking leafhoppers, not chewing beetles.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Phytoplasmas are specialized, wall-less bacteria (class Mollicutes) that are obligate parasites of plants and insect vectors.
They cause a wide range of diseases characterized by symptoms like yellowing, phyllody, and witches' broom.

Step 2: Detailed Explanation:
Let us analyze both statements:
- Statement (I) is correct: Phytoplasmas are phloem-limited pathogens.
They reside exclusively within the sieve tube elements of the phloem tissue, where they rely on the host's phloem sap flow for nutrients and translocation throughout the plant.
- Statement (II) is incorrect: Because phytoplasmas are restricted to the phloem, they cannot be transmitted by chewing insects like beetles, which feed on entire leaf tissues.
Instead, they are transmitted specifically by phloem-feeding insects (sucking insects) that insert their stylets directly into sieve tube elements to feed on sap.
The primary vectors of phytoplasmas are leafhoppers (Cicadellidae), planthoppers (Fulgoroidea), and psyllids (Psyllidae).
Therefore, Statement (I) is correct, but Statement (II) is incorrect.

Step 3: Final Answer:
Hence, the correct option is (C).