The multifaceted role of microRNA in medicinal plants

The active ingredients of medicinal plants are often regarded as secondary metabolites (SMs), and microRNAs (miRNAs) play an important regulatory role in their accumulation. Based on the increased availability of medicinal plant genomes and developed multi-omics techniques, new insights into the function of medicinal plant miRNA continue to emerge. On the one hand, miRNAs regulate the growth and development of organs of medicinal plants, such as roots, stems, leaves, and flowers, which directly impacts the production of phytomedicine. On the other hand, miRNAs are directly involved in the biosynthesis regulation of SMs such as alkaloids, flavonoids, and terpenes that contribute to the therapeutic properties. Furthermore, several miRNAs from medicinal plants have been suggested to act directly as antineoplastic or antiviral. In this review, we summarized the multifaceted roles of medicinal plant miRNAs, highlighting their functions as regulators within plants and as active ingredients that exert effects through cross-kingdom regulatory mechanisms. These roles not only contribute to enhancing the yield and quality of medicinal plants but also offer possibilities for the development of novel therapeutics, holding significant implications for the medicinal plant industry and human health.