Lead (Pb) contamination poses a major threat to medicinal plants by impairing photosynthesis, disturbing metabolism, and overactivating stress signaling. Here, we examined the responses of ginseng ( Panax ginseng C.A. Meyer) to Pb stress and the mitigating role of methyl jasmonate (MeJA) using integrated physiological, biochemical, metabolomic, transcriptomic, and network analyses. The exposure to Pb reduced photosynthetic efficiency, root biomass, pollen viability, and root activity, while inducing oxidative damage. Specifically, at the red fruit stage, Pb exposure caused a significant reduction in SPAD values (chlorophyll content) compared to the control group (P < 0.05). Root morphology was also significantly affected by Pb exposure, with reduced root growth and symptoms of root rot observed in the Pb1000 treatment (P < 0.05). The MeJA supplementation partially restored photosynthetic performance, improving Pn (P < 0.05), reinforced antioxidant defenses, and significantly improved root biomass relative to Pb-only treatments (P < 0.05). Additionally, MeJA treatment enhanced the activity of antioxidant enzymes, including SOD and CAT, and reduced oxidative damage as indicated by lower MDA levels (P < 0.05). Omics profiling revealed that MeJA reprogrammed carbohydrate metabolism, phenylpropanoid biosynthesis, and hormone signaling, with MYB, bHLH, and ERF transcription factors linking these pathways. In contrast, Pb disrupted carbon and glutathione metabolism, lipid remodeling, and secondary metabolism, while excessively activating MAPK signaling and endocytosis. Integrated analyses showed that MeJA alleviated these effects through dual regulation: reactivating Pb-suppressed phenylpropanoid, flavonoid, terpenoid, and hormone pathways, while suppressing Pb-induced overactivation of stress signaling. Collectively, MeJA mitigates Pb toxicity in ginseng by coordinated reprogramming of metabolism and gene expression, simultaneously enhancing defense metabolism and restraining maladaptive signaling. These findings advance understanding of hormone-mediated detoxification and suggest that MeJA could serve as an eco-friendly regulator to improve stress resilience and safeguard medicinal crop quality in contaminated soils. • MeJA alleviates Pb toxicity in ginseng through a dual regulatory mechanism. • MeJA counteracts Pb-induced repression of phenylpropanoid-flavonoid, terpenoid, and hormone signaling pathways. • MeJA suppresses Pb-driven overactivation of MAPK signaling and endocytosis to prevent maladaptive responses. • Transcription factors (MYB, bHLH, ERF, NAC) act as central nodes integrating metabolic and signaling adjustments.
Yang et al. (Fri,) studied this question.