RNA interference (RNAi)

Definition

A conserved cellular mechanism in which double-stranded RNA triggers sequence-specific degradation of complementary messenger RNA, resulting in post-transcriptional gene silencing. In arthropods, RNAi operates through the Dicer and Argonaute protein families to cleave target transcripts or block their translation.

Etymology

RNA (ribonucleic acid) + interference (disruption of normal function)

Example

In the flour beetle Tribolium castaneum, injection of double-stranded RNA targeting the Distal-less gene produces truncated legs, demonstrating RNAi's utility for dissecting developmental genetics in insects. RNAi is also deployed commercially in crops to protect against coleopteran and lepidopteran pests.

Synonyms

• RNA silencing
• post-transcriptional gene silencing
• PTGS

Related Terms

• gene silencing
• small interfering RNA
• microRNA
• Dicer
• Argonaute
• Functional genomics
• transgenic crop
• pest-resistant plant

Usage Notes

RNAi is used absolutely (the mechanism) or relatively (RNAi-mediated knockdown). In entomology, distinguish experimental RNAi (dsRNA injection, feeding, or transgene expression) from natural RNAi roles in antiviral defense and transposon suppression. Systemic RNAi—where silencing spreads between tissues—varies markedly among arthropod groups, being robust in Coleoptera and some Hemiptera but limited in Diptera like Drosophila. The term does not imply complete gene knockout; phenotypic penetrance depends on dsRNA dose, delivery method, and target tissue accessibility.