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अवधारणा स्पष्टीकरण और वीडियो७१०
समय सारणी१६
पाठ्यक्रम

Applications of Biotechnology in Agriculture - Mechanism of RNA Interference

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Estimated time: 14 minutes
CBSE: Class 12
CISCE: Class 12

Initiation in the Host Plant

  • Nematode-specific genes are introduced into the host plant (tobacco cell) using an Agrobacterium vector.
  • The introduced DNA produces both sense and anti-sense RNA within the host cells.
  • Because these two RNAs are complementary to each other, they pair up to form double-stranded RNA (dsRNA).
  • The formation of this dsRNA is what initiates the RNA interference (RNAi) process.
CBSE: Class 12
CISCE: Class 12

Processing in the Nematode Cell

  • The dsRNA produced by the plant enters the cell of the nematode.
  • An enzyme known as dicer (or protein dicer) cuts the long dsRNA into small fragments.
  • These small RNA fragments are known as small/short interfering RNAs (siRNA).
  • The siRNA molecules pass through the RNA-induced silencing complex (RISC), where the duplex unwinds and the RNA is activated.
  • The siRNA binds with the Argonaute protein (also called slicer) to form the functional RISC.
  • During this unwinding, one strand of the siRNA is removed, digested, and discarded, leaving RISC with single-stranded siRNA.
CBSE: Class 12
CISCE: Class 12

Target Cleavage and Gene Silencing

  • Inside the nematode's nucleus, DNA naturally transcribes into mRNA.
  • The remaining single-stranded siRNA within the RISC binds to this specific target mRNA produced by the pathogen.
  • RISC then cleaves the target mRNA into fragments, promoting RNA degradation.
  • This cleavage completely blocks the translation of the mRNA, silencing the specific mRNA of the nematode.
  • As a consequence, the parasite cannot survive in the transgenic host, and the transgenic plant successfully protects itself.
CBSE: Class 12
CISCE: Class 12

RNA Interference

CBSE: Class 12
CISCE: Class 12

Mechanism of RNAi

CBSE: Class 12
CISCE: Class 12

Applications of RNAi

  • It is frequently used to study the functions of genes in cell cultures and model organisms.
  • It serves as a tool for gene mapping and annotation in plants.
  • It can silence specific gene sequences, which can be utilised to silence genes that cause cancer.
  • It is used in treatments for bacterial, viral, and parasitic diseases.
  • It can also be applied to relieve pain and modulate sleep.
CBSE: Class 12
CISCE: Class 12

Key Points: Mechanism of RNA Interference

  • Nematode-specific genes are introduced into the host plant using an Agrobacterium vector to synthesise complementary sense and antisense RNA.
  • These complementary RNA strands pair together within the host cells to form a double-stranded RNA (dsRNA) molecule.
  • Once the nematode ingests the dsRNA, an enzyme called dicer cleaves it into smaller fragments known as small interfering RNAs (siRNA).
  • The siRNA binds with the Argonaute protein to form the RNA-induced silencing complex (RISC), where it unwinds into a single active strand.
  • This single-stranded siRNA guides the RISC to bind specifically to the complementary target mRNA produced by the nematode.
  • The complex cleaves the target mRNA, effectively blocking its translation into protein and neutralising the parasite to protect the plant.

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