Question

Which of the following nematode induces Syncytium cells?
A. Meloidogyne incognita
B. Tylenchulus semipenetrans
C. Heterodera avenae
D. Rotylenchulus reniformis
Choose the correct answer from the options given below

• A. A only
• B. B only
• C. A and B only
• D. C and D only

Hint:

Root-knot nematodes (Meloidogyne) induce giant cells via karyokinesis without cytokinesis, whereas cyst (Heterodera) and reniform (Rotylenchulus) nematodes induce syncytia via cell wall dissolution.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Sedentary endoparasitic nematodes modify host root vascular tissues to create specialized feeding structures.
These modifications include giant cells and syncytia, which serve as metabolic sinks to feed the developing nematode.

Step 2: Detailed Explanation:
Let us analyze the specific host cell modifications induced by the different nematode groups:
1. Meloidogyne incognita (A): Root-knot nematodes induce the formation of giant cells.
These cells are formed when the nematode injects salivary secretions into vascular cells, triggering repeated rounds of nuclear division (karyokinesis) without cell wall division (cytokinesis).
This results in giant, multinucleated cells.
2. Tylenchulus semipenetrans (B): The citrus nematode induces specialized nurse cells in the root cortex, which are modified uninucleate cells.
3. Heterodera avenae (C): Cyst nematodes induce the formation of a syncytium.
A syncytium is formed when cell walls between adjacent vascular cells dissolve, causing the protoplasts of hundreds of cells to fuse into a single, large, multinucleated cytoplasm.
4. Rotylenchulus reniformis (D): Reniform nematodes also induce a syncytium in the root pericycle and endodermis, similar to cyst nematodes.

Step 3: Final Answer:
Therefore, syncytium cells are induced by Heterodera avenae and Rotylenchulus reniformis (C and D only).