96. Which one among the following is an important constituent of RNA induced silencing complex
in plants?
A. Argonaute
B. LHP1
C. RNaseP
D. RNA dependent RNA polymerase

Detailed Explanation:

The RNA-induced silencing complex (RISC) plays a crucial role in the regulation of gene expression in plants, particularly in processes like RNA interference (RNAi), a mechanism for silencing specific gene expression. RISC is involved in post-transcriptional gene silencing, a form of gene regulation that influences various biological processes such as virus defense, transposon control, and regulation of developmental processes.

Key Components of the RNA-Induced Silencing Complex (RISC):

Among the different components that form the RISC in plants, Argonaute is one of the most important and well-studied proteins.

Argonaute:

• Role in Gene Silencing: Argonaute proteins are essential components of the RNA-induced silencing complex. They directly interact with small RNA molecules, such as microRNAs (miRNAs) or small interfering RNAs (siRNAs), and mediate the silencing of complementary target mRNA.

• Mechanism: Once RISC binds to an RNA molecule, the Argonaute protein helps guide the complex to the target RNA, where it can induce cleavage or translation repression, leading to reduced expression of the target gene.

Other Components:

• LHP1: LHP1 (LHP1-like protein 1) is involved in gene silencing but does not directly form part of the RISC complex. It functions in chromatin remodeling during silencing, not as a primary constituent of RISC.

• RNaseP: RNaseP is an enzyme involved in RNA maturation, particularly in the processing of precursor tRNA. It is not a part of RISC but has a distinct role in RNA processing.

• RNA-Dependent RNA Polymerase: While RNA-dependent RNA polymerases (RDRPs) are involved in the amplification of small RNA molecules during RNA silencing, they are not direct constituents of RISC. They play a role in the synthesis of double-stranded RNA, which is then processed by other components to form siRNAs.

Conclusion:

The most important constituent of the RNA-induced silencing complex in plants is Argonaute. This protein is directly involved in the gene silencing process by interacting with small RNA molecules and guiding them to their target mRNAs.

Correct Answer:

A. Argonaute