Hispidulin mediates long-term cadmium tolerance and accumulation capacity in Artemisia argyi

Cadmium (Cd) pollutant poses severe risks to ecosystems. Identifying suitable plant species with large biomass, economic value, and stable Cd tolerance and accumulation is urgently needed for Cd removal. Here, Artemisia argyi cultivar ‘Xiang Ai’ (XA) exhibited remarkable Cd tolerance together with sustained and stable Cd-accumulation capacity throughout its entire growth period. Normal growth was maintained even under 100 mg/kg Cd exposure, and a stable Cd-enrichment level of 7045.74 μg per plant was recorded. Cd was predominantly accumulated in the aboveground organs, particularly in the lower leaves. Physiological, biochemical, and multi-omics analyses revealed that its Cd tolerance was mainly achieved through a coordinated antioxidant defense system, in which enhanced SOD-mediated enzymatic activity acted synergistically with hispidulin-enriched non-enzymatic protection driven by the upregulation of flavonoid biosynthesis genes. Moreover, hispidulin was further suggested to potentiate SOD activity, thereby reinforcing the enzymatic detoxification of ROS. Additionally, hispidulin was implicated as a putative signaling molecule capable of recruiting Cd-tolerant rhizosphere microorganisms (e.g., norank_o_Chloroplast), which further strengthened Cd resistance in XA. Collectively, this study provides new insights into the Cd tolerance mechanisms of A. argyi, and establishes a theoretical basis for ecological restoration of Cd-contaminated soils and the safe utilization of hyperaccumulative medicinal plant resources.