Hydrogen Peroxide-Oxidative Signaling Enhances Biosynthesis of Specialized Metabolites in Baccharis conferta Kunth

Hydrogen peroxide (H₂O₂) regulates plant metabolism. This study examined its effect on the biosynthesis of specialized metabolites in Baccharis conferta, a medicinal plant rich in phenolics and terpenes. Plants were elicited with 25 µM and 250 µM H₂O₂. Phenolic changes were evaluated by total phenolic content (TPC), total flavonoid content (TFC), phenylalanine ammonia-lyase (PAL) activity, and LC-MS analysis of flavonoids and hydroxycinnamic acids. Meanwhile, terpene changes were evaluated by HPTLC, total terpene content (TTC), and expression of the 1-deoxy-D-xylulose-5-phosphate synthase (Bco-DXS1) gene. H₂O₂ markedly modulated both pathways. Phenolic metabolism was activated, particularly under 25 µM H₂O₂, with PAL activity increasing by 52%, TPC by 42%, and TFC by 50% relative to the control. Chemical analysis revealed that five compounds, including chlorogenic acid, differed significantly across treatments. Gene expression analysis showed that 25 µM H₂O₂ upregulated Bco-DXS1 and increased TTC, whereas 250 µM H₂O₂ repressed gene expression but still enhanced terpene accumulation. Overall, these results suggest that moderate H₂O₂ levels function as a signaling molecule in B. conferta, simultaneously boosting phenolic and terpene pathways. This highlights controlled H₂O₂ elicitation as an effective biotechnological approach to increase the production of valuable metabolites in medicinal plant cultures.