Engineered elicitation in Artemisia annua L. callus cultures alters artemisinin biosynthesis, antioxidant responses, and bioactivity

Artemisia annua L. callus cultures are valuable systems for producing the antimalarial artemisinin, yet enhancing yields via elicitation is challenging. This study delineates how combining plant growth regulators (PGRs) and silver nitrate (AgNO3) affects biomass, artemisinin biosynthesis, antioxidant responses, and bioactivity. A. annua calli were treated with PGRs (BAP, NAA, 2,4-D) and elicited with AgNO3 to assess resulting metabolic and bioactive profiles. While 1 mg/L AgNO3 in media containing 5 mg/L BAP and 1 mg/L NAA augmented fresh and dry biomass by 182% and 227%, it decoupled growth from secondary metabolism; artemisinin content reached only 0.83-fold that of wild plants. Notably, Silver ions showed context-specific roles, attenuating oxidative stress under 2,4-D-induced high stress but exacerbating it under NAA-mediated low stress. Extracts demonstrated differential antimicrobial activity, with the most significant inhibition observed against Staphylococcus aureus. Specific elicitor combinations drive metabolic trade-offs in A. annua callus, providing a framework to optimize the controlled biosynthesis of therapeutic compounds.