Silver nanoparticles enhance organogenesis, total flavonoid and anthocyanin contents in Gynura pseudochina tissue culture

Gynura pseudochina is an Indonesian medicinal herb valued for its flavonoid and anthocyanin content. Despite its pharmacological importance, approaches to enhance metabolite accumulation and clarify associated molecular responses remain limited. This study evaluated 10 nm silver nanoparticles (AgNPs) as elicitors of in vitro growth, metabolite accumulation, gene expression, and sequence-based characterization. We observed dose-dependent modulation of organogenesis and biomass, with improved growth at moderate concentrations (notably 30 µg/L). Flavonoid and anthocyanin contents peaked at 60 µg/L. RAPD profiles remained monomorphic across the tested AgNP concentrations, indicating that no detectable polymorphic variation was observed within the resolution limits of the RAPD markers employed in this study. Partial cDNAs of GpPAL, GpDFR, and GpCHS were successfully isolated, and phylogenetic analysis showed close relationships with Gynura bicolor, with sequence similarities of 92.80%, 100%, and 98.31%, respectively. qRT-PCR revealed strong induction of GpPAL at 60 µg/L, whereas GpDFR and GpCHS were downregulated. Overall, AgNPs effectively modulated growth and phenylpropanoid metabolism, providing a reproducible nano-elicitation framework for medicinal plants with limited genomic resources.