Multi-omics elucidation of ZnO quantum dots enhancing growth and bioactive compound biosynthesis in Ligusticum chuanxiong Hort

Zinc (Zn) is essential for plant growth and development. In this study, Zn oxide quantum dots (ZnO QDs) were synthesized and applied to Ligusticum chuanxiong seedlings to examine their regulatory effects on growth and bioactive compound biosynthesis. Foliar-applied ZnO QDs exploited nanoscale properties to enhance Zn accumulation, increase photosynthetic pigment levels, and promote carbohydrate and protein biosynthesis. Levels of endogenous phytohormones, including cytokinin (6-benzyladenine, 6-BA) and auxin (indole-3-acetic acid, IAA), were also elevated. ZnO QDs reduced lipid peroxidation through selective activation of catalase and polyphenol oxidase, alleviating oxidative damage. They also enhanced the accumulation of key medicinal compounds: chlorogenic acid, senkyunolide A, ligustilide, and 3-n-butylphthalide. Multi-omics analyses identified two transcriptionally regulated pathways: genes in the tryptophan pathway (TAR4.1, TAR4.2, YUCCA6, and AAO) promoted auxin biosynthesis, whereas genes in the phenylalanine metabolic pathway (PALs, 4CLs, and HCTs) redirected flux toward chlorogenic acid and related metabolites. ERF transcription factors were predominant in regulating both auxin and chlorogenic acid biosynthesis. These findings demonstrate that ZnO QDs coordinate Zn delivery, antioxidant activation, and biosynthesis of medicinal metabolites, supporting a nanotechnology-based strategy for improving the quality and yield of medicinal crops.