• Transitive siRNAs are generated via RDR-dependent synthesis of dsRNA, enabling amplification and spread of RNAi silencing signals beyond primary targets.
• In Arabidopsis, RDR1 and RDR6 cooperate with RISC and aberrant RNAs to produce transitive siRNAs in diverse subcellular compartments, revealing complex regulatory mechanisms.
• Transitive siRNAs play crucial roles in plant development and stress adaptation, with potential applications in crop improvement and biotechnology.
• The review highlights unresolved questions regarding RDR recruitment and the full spectrum of transitive siRNA functions, guiding future research.