Elicitors-induced modulation of plant performance, essential oil composition, and iridoid biosynthesis in Valeriana jatamansi Jones cultivated under controlled vertical aeroponics

Abstract The integration of aeroponic cultivation and elicitation offers an efficient strategy for enhancing biomass production and specialized metabolite accumulation in medicinal plants. In the current investigation, foliar application of fungal endophyte (FE), seaweed extract (SWE), and salicylic acid (SA) were applied to aeroponically cultivated Valeriana jatamansi to evaluate their effect on morphological growth, biomass yield, physiological performance, antioxidant defence, essential oil production, valepotriate accumulation, biosynthetic gene expression, and antimicrobial activity. SA treatment significantly enhances morphological growth, whereas FE promotes biomass accumulation. Elicitor treatment showed improved photochemical performance and antioxidant defence as indicated by reduced malondialdehyde and H₂O₂ levels and enhanced superoxide dismutase and catalase activities in leaf and root tissues. SWE produced the highest essential oil yield (2.50%) (v/w) and patchouli alcohol concentration (238.31 mg/L), while FE resulted in the highest relative abundance of patchouli alcohol (43.27%) in the oil. FE also markedly enhanced root valepotriate accumulation, with maximum acevaltrate (0.47%), didrovaltrate (0.53%), and valtrate (3.10%) contents. Consistently, qRT-PCR profiling revealed enhanced expression of iridoid pathway genes, including SLS , IS , 7DLGT and 7DLS , following elicitor treatment in leaf and root tissue. Essential oil exhibited strain-dependent antimicrobial activity, with Bacillus subtilis being the most susceptible strain (MIC 0.06 mg/mL). Overall, these findings demonstrate that combining aeroponic cultivation with targeted elicitation can effectively enhance biomass productivity, physiological resilience, essential oil quality, and valuable specialized metabolites in V. jatamansi , presenting a potential strategy for sustainable, scalable production of high-value medicinal plant products.