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.