Small RNAs, big impact: miRNAs and circRNAs in the post-transcriptional control of fruit ripening

Abstract Fruit ripening is a highly coordinated developmental process that determines the quality, nutritional value, and shelf life of horticultural crops. Recent advances have revealed that small noncoding RNAs, especially microRNAs (miRNAs) and circular RNAs (circRNAs), are central regulators of post-transcriptional gene expression during fruit development and maturation. miRNAs fine-tune ripening by targeting key transcription factors and enzymes involved in hormonal signaling, pigment biosynthesis, aroma formation, and cell wall modification. In parallel, circRNAs function as competing endogenous RNAs that modulate miRNA activity, integrating developmental and environmental cues into metabolic regulation. Although substantial progress has been made in identifying miRNAs and their targets, functional evidence for circRNA-mediated regulation remains limited and largely predictive. Integrative multi-omics approaches, combining transcriptomic, metabolomic, and epigenomic data, are expanding our understanding of these complex regulatory networks. Moreover, genome-editing and RNA-based technologies, such as CRISPR/Cas and artificial miRNAs, provide promising tools for modulating small RNA pathways to enhance fruit quality traits and post-harvest performance. This review synthesizes current knowledge on miRNA and circRNA function in fruit ripening, highlights emerging gaps, and discusses future directions for exploiting RNA-mediated regulation in sustainable fruit crop improvement. Graphical Abstract