A farmer reports stunted, spindle-shaped potato plants. Lab analysis reveals circular RNA molecules without protein coats. What is the causative agent?
A) Bacteria
B) Virus
C) Mycoplasma
D) Viroid
Answer (2)
The causative agent for the stunted potato plants is a viroid, which is characterized by small, circular RNA molecules without protein coats. Viroids specifically infect plants and can lead to diseases that exhibit these symptoms. Therefore, the correct answer is D) Viroid.
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The causative agent responsible for the stunted, spindle-shaped potato plants is a viroid, which is option D.
Viroids are small, circular RNA molecules that do not have a protein coat, distinguishing them from viruses. These pathogens are known to infect plants, causing a variety of plant diseases. Characteristics of viroids include:
Structure: Viroids are composed of single-stranded, circular RNA without any protein coat. This RNA is much smaller than that of viruses, making viroids the smallest known infectious agents.
Host specificity: Viroids primarily infect plants and are responsible for diseases in many economically important crops, including potatoes, tomatoes, and citrus fruits.
Mode of action: Due to their simple structure, viroids replicate inside the host plant's cells, often disrupting normal cellular processes and leading to symptoms such as stunted growth and abnormal plant morphology, as observed in the affected potato plants.
Transmission: Viroids can spread through mechanical means, such as gardening tools or insect vectors, and through seeds or pollen.
In this specific scenario, the laboratory analysis revealing circular RNA molecules without protein coats is a clear indication of a viroid infection, as described in the symptoms of the potato plants.
