Foliar nanoparticles alleviated cadmium-induced phytotoxicity in dandelion via regulation of ionomics, metabolomics, and rhizobacterial networks.

Foliar application of beneficial nanoparticles (NPs) demonstrates potential in alleviating heavy metal (HM) stress in plants. Yet, their effects on rhizosphere microbial communities, nutrient dynamics, and metabolic adaptations in dandelion remain underexplored. This study investigated the mechanisms underlying Cadmium (Cd) stress mitigation in dandelion via foliar application of ZnONPs, TiO2NPs, SiO2NPs, and Fe3O4NPs by integrating high-throughput sequencing, metabolomic profiling, and physiological analyses. Moderate concentrations of ZnONPs (ZM) and low concentrations of SiO2NPs (SL) elevated proline content (31.14 % and 82.41 %) and increased soluble protein levels (72.95 % and 78.50 %). ZM further reduced malondialdehyde levels by 18.38 %. Spraying ZnONPs, TiO2NPs, and Fe3O4NPs enhanced the accumulation of essential nutrients and reduced Cd accumulation (24.58 %, 17.37 %, and 20.21 %). Metabolic reprogramming in leaves under NP treatments drove the accumulation of palmitic acid, stearic acid, D-glucopyranoside, and myo-inositol, with key physiological indicators (plant height, chlorophyll content, and total phenols content) showing significant positive correlations with differentially expressed metabolites and nutrient profiles. Notably, foliar application of TiO2NPs and SiO2NPs significantly enhanced rhizosphere bacterial diversity and total species richness, particularly enriching stress-resistant phyla such as Proteobacteria, Chloroflexi, and Firmicutes, which facilitated Cd immobilization, organic pollutant degradation, and bioactive compound production. These findings provided insights into nanoparticle-mediated stress mitigation strategies and highlighted the potential of NPs to enhance agricultural sustainability in contaminated environments.