Physiological and molecular mechanisms of zinc oxide quantum dots alleviating cadmium stress in Ligusticum chuanxiong

This study establishes zinc oxide quantum dots (ZnO QDs) as precision-engineered nanoparticles for alleviating cadmium (Cd) toxicity in the medicinal plant Ligusticum chuanxiong . Synthesized via a sol–gel method, the resulting ZnO QDs exhibited distinct physicochemical properties, including quantum confinement-enhanced Zn²⁺ release and high colloidal stability, which are conducive to efficient nutrient delivery and plant protection. Foliar application of ZnO QDs at an optimized concentration effectively restored growth parameters and reduced Cd accumulation in Cd-stressed plants, while concurrently enhancing zinc uptake. The treatment markedly attenuated oxidative stress, as evidenced by reduced levels of hydrogen peroxide and malondialdehyde, and modulated antioxidant enzyme activities. Additionally, ZnO QDs significantly promoted the accumulation of pharmacologically active compounds, including chlorogenic acid and senkyunolides. Integrated transcriptomic and metabolomic analyses revealed that ZnO QDs downregulated key Cd transporters (e.g., YSL and bZIP families) and plant cadmium resistance (PCR) proteins, which were activated under Cd stress, and restored the levels of stress-responsive metabolites. These findings underscore the dual functionality of ZnO QDs in not only mitigating Cd phytotoxicity but also enhancing the biosynthesis of valuable phytochemicals, providing a mechanistic basis for their application in combating cadmium contamination in medicinal plants. • ZnO QDs reduce Cd content in Ligusticum chuanxiong. • ZnO QDs decrease oxidative damage in Ligusticum chuanxiong. • ZnO QDs increase bioactive compounds in seedlings. • ZnO QDs downregulate heavy metal transporter genes in seedlings.