RNA Activation in Plants: Current Evidence and Molecular Insights.

The current scientific literature presents increasing evidence for the existence of the RNA activation (RNAa) phenomenon in eukaryotes. RNAa is a molecular mechanism by which gene expression is activated through small activating RNAs (saRNAs) and microRNAs (miRNAs). The RNAa pathway shares many similarities with RNA interference (RNAi), yet it represents a distinct regulatory process. While RNAi is a relatively well-characterized process involving Dicer-like endonucleases that process double-stranded RNAs (dsRNAs) into small interfering RNAs (siRNAs), ultimately leading to gene silencing, the molecular mechanisms underlying RNAa remain poorly understood. This review summarizes and discusses the current knowledge of RNA-mediated activation of gene expression in plants, highlighting this emerging research area beyond gene silencing. While research on RNAa in plants remains limited, available data support the existence of RNA-triggered gene activation and RdDM-associated transcriptional derepression at specific plant loci. Whether these phenomena constitute a unified RNAa pathway analogous to that described in animals remains to be determined. A broader understanding of RNAa-related processes is essential for advancing plant science and developing innovative strategies in plant molecular biology and biotechnology.