The causative agent of potato spindle tuber disease is composed of

Answer

To answer the question regarding the causative agent of potato spindle tuber disease, we can follow these steps:

### Step 1: Identify the Disease
The question asks about the causative agent of potato spindle tuber disease. This disease affects the shape and growth of potatoes, causing them to develop a spindle-like appearance.

### Step 2: Determine the Causative Agent
The causative agent of potato spindle tuber disease is identified as a type of pathogen. In this case, it is important to note that the agent responsible for this disease is not a traditional virus or bacterium.

### Step 3: Understand the Nature of the Causative Agent
The causative agent of potato spindle tuber disease is classified as a "Viroid." Viroids are unique infectious agents that are smaller than viruses and consist solely of a short strand of circular RNA. They lack a protein coat, which distinguishes them from viruses.

### Step 4: Characteristics of Viroids
Viroids are composed of:
- Single-stranded RNA
- Typically consist of about 300 nucleotides
- They do not have a protein coat, which is a characteristic feature of viruses.

### Step 5: Conclusion
Thus, the causative agent of potato spindle tuber disease is composed of Viroids, which are essentially made up of RNA.

### Final Answer
The causative agent of potato spindle tuber disease is composed of Viroids (RNA).

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