RNA-based antiviral agent

Context:

Germany-based researchers have developed an RNA-based antiviral agent using RNA silencing techniques to protect plants, especially against the Cucumber Mosaic Virus (CMV), which causes 25–30% banana crop loss in India.

About the Antiviral Agent and Techniques Used:

Researchers are leveraging RNA interference (RNAi) to enhance plant immunity:

Host-Induced Gene Silencing (HIGS):
- Plants are genetically modified to produce double-stranded RNA (dsRNA) that targets viral genes.
- Provides lifelong protection without needing reapplication.
Spray-Induced Gene Silencing (SIGS):
- RNA sprays are applied to plant leaves.
- RNA is absorbed and triggers the plant’s immune system—no genetic modification needed.

How Plants Use RNA Silencing Against Viruses:

When a virus infects a plant, it introduces dsRNA.
The plant detects this and activates Dicer-like enzymes (DCLs) to chop the dsRNA into small interfering RNAs (siRNAs).
These siRNAs guide the plant’s cellular machinery to degrade the viral RNA, halting infection.
However, viruses can mutate quickly, making some siRNAs ineffective.

What is RNA silencing?

RNA silencing is a natural gene regulation process that uses siRNA or miRNA to degrade or suppress target RNA (mRNA).
This prevents the mRNA from producing harmful or unwanted proteins.
Acts as a defence mechanism in plants and other organisms against viruses.

Prelims Question:

Q. Which of the following statements regarding RNA Silencing is/are correct?

RNA silencing involves siRNA or miRNA that can bind to viral or messenger RNA.
Host-Induced Gene Silencing (HIGS) involves applying RNA sprays externally to the plant.
RNA silencing can act as a natural defense mechanism in plants against viral infections.

Select the correct answer:
(a) 1 and 2 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2 and 3

Answer: (b) 1 and 3 only