Question

Identify the correct sequence of steps in the RNA-interference (RNAi) process to develop nematode resistant plants.
i) Silencing of specific mRNA of the nematode
ii) Formation of sense and antisense RNA
iii) dsRNA formation
iv) Introducing nematode-specific genes into plant

A. i, ii, iv, iii
B. iii, ii, I, iv
C. iv, ii, iii, i
D. iv, i, ii, iii

Answer 1

Hint: To protect a plant against nematodes, genes that provide resistance to nematodes have to be introduced in the DNA of the plant. For RNA interference to occur, it is important for the DNA to be converted into mRNA. Once the nematode specific RNA is present, it can be silenced using the technique of RNA interference.

Complete answer:
To develop nematode-resistant plants, the sequence of steps for RNA interference would be as follows:
- Introducing nematode specific genes into plant
- Formation of sense and antisense RNA
- dsRNA formation
- silencing of specific mRNA of the nematode

RNA interference is the process by which the expression of a gene or a set of genes is inhibited by RNA molecules that interfere with the activity of the target RNA molecules. This can be achieved through double-stranded RNA.

To provide resistance against nematodes, the plant should have the genes for the nematode. Once the genes for nematodes are introduced in the plant, sense, and antisense RNA molecules are created. A double-stranded RNA can only be formed when there are sense and antisense RNA strands.

An enzyme known as dicer cuts the dsRNA into small fragments known as small interfering RNA (siRNA). The siRNA helps in degrading the target RNA, thereby inhibiting the process of translation.

Hence, the correct answer is option (C).

Note: The process of RNA interference finds many applications in the field of medicine. It has been used to target and silence sequences in the DNA that can cause cancer in a person. RNAi has even been used to treat certain bacterial and viral diseases, managing pain, and modulating the sleep cycle.