Hydrogen-mediated alleviation effects of cadmium toxicity for sustainable artemisinin production in Artemisia annua

Artemisia annua, a traditional Chinese medicinal plant, is renowned for producing artemisinin, a potent antimalarial drug. However, cadmium pollution in the soil significantly inhibits the growth and metabolic processes of A. annua, jeopardizing safe and high-yield artemisinin production. Here, we explore the effects of hydrogen on the physiological responses of 40-day-old A. annua under 80 mg·L⁻¹ cadmium stress, utilizing the hydrogen storage material MgH₂. Our findings reveal that MgH₂ treatment alone has a limited impact on the growth and development of A. annua. However, when combined with cadmium stress, MgH₂ treatment restores approximately 10% of the biomass lost due to cadmium stress. MgH₂ treatment also significantly increases endogenous hydrogen in seedlings, reducing the expression of cadmium uptake and transport genes induced by heavy metal, leading to lower cadmium absorption and accumulation. Additionally, MgH₂ mitigates the adverse effects on leaf gas exchange and chlorophyll content, restoring about 15% of photosynthetic capacity compromised by cadmium exposure. Notably, MgH₂ also modifies the soil microbial community structure and enhances carbon cycling, suggesting its beneficial role in remediating cadmium damage in soil. Finally, our results demonstrate that MgH₂ can fully restore glandular-secreting trichome (GST) density and artemisinin production at 80 mg·L⁻¹ cadmium concentrations in A. annua. Given the primary use of A. annua for compound extraction, our findings provide a new safe and sustainable strategy for cultivation and production of traditional Chinese medicinal plants.