Elicitor-Mediated Enhancement of Secondary-Metabolite Biosynthesis in Juniperus (Cupressaceae): Current Advances and Future Perspectives
Juniperus species are a rich source of pharmacologically important secondary metabolites, including terpenoids, lignans, flavonoids, and phenolic compounds. However, the commercial utilization of these metabolites is limited by the plant’s slow growth, poor natural regeneration, and environmental variability affecting metabolite accumulation. Integrating plant tissue culture with elicitation strategies is a promising approach for sustainably producing these valuable compounds. This review summarizes the diversity, biological activities, and biotechnological significance of secondary metabolites in Juniperus, focusing on tissue culture systems and enhancement of metabolite biosynthesis through elicitors. It critically evaluates the current knowledge of the effects of signaling compounds such as methyl jasmonate (MeJA), jasmonic acid (JA), and salicylic acid (SA), as well as other abiotic and biotic elicitors including silver nanoparticles (AgNPs), chitosan, and chito-oligosaccharides. Particular attention is given to their effects on podophyllotoxin, phenolic, flavonoid, and other bioactive metabolite accumulation. Elicitation responses appear to depend strongly on species, culture system, elicitor type, and treatment conditions. This review also highlights major knowledge gaps, particularly the limited understanding of the regulatory mechanisms controlling secondary-metabolite biosynthesis in Juniperus species. Overall, the available evidence suggests that integrating optimized elicitation strategies with transcriptomics, metabolomics, and metabolic engineering could improve our understanding of secondary metabolite regulation and facilitate the development of sustainable Juniperus tissue culture platforms for producing high-value natural products.