Tobacco plants were protected from the nematode Meloidogyne incognita by RNA interference (RNAi). Arrange the following steps in the correct sequence:
A. A double-stranded RNA (dsRNA) is formed and initiates RNAi.
B. Nematode-specific genes are introduced into the host plant using Agrobacterium vectors.
C. The specific mRNA of the nematode is silenced.
D. Both sense and anti-sense RNA are produced in the host cells.
E. The parasite cannot survive in the transgenic host.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → B, D, A, C, E
RNA interference (RNAi) silences a specific mRNA with a complementary double-stranded RNA (dsRNA). It was used to protect tobacco roots from a nematode. The steps follow one another as below.
First – B. Nematode-specific genes are introduced into the host plant using Agrobacterium vectors. The plant must first receive the nematode genes; Agrobacterium carries them in.
Second – D. Both sense and anti-sense RNA are produced in the host cells. The genes were introduced so that they make both RNA strands.
Third – A. A double-stranded RNA (dsRNA) is formed and initiates RNAi. The sense and anti-sense RNAs are complementary, so they pair to form dsRNA, which starts RNAi.
Fourth – C. The specific mRNA of the nematode is silenced. The dsRNA binds the nematode’s mRNA and stops its translation.
Fifth – E. The parasite cannot survive in the transgenic host. With its mRNA silenced, the nematode cannot live in the plant, and the plant is protected.
NCERT Extract:
Biotechnological Applications in Agriculture – “… This method involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA (silencing). … Using Agrobacterium vectors, nematode-specific genes were introduced into the host plant …. The introduction of DNA was such that it produced both sense and anti-sense RNA in the host cells. These two RNA’s being complementary to each other formed a double stranded (dsRNA) that initiated RNAi and thus, silenced the specific mRNA of the nematode. The consequence was that the parasite could not survive in a transgenic host expressing specific interfering RNA.”