Physiological and metabolomic analyses reveal that Fe3O4 nanoparticles ameliorate cadmium and arsenic toxicity in Panax notoginseng

Abstract

Heavy metal(loid)-contaminated available arable land seriously affects crop development and growth. Engineered nanomaterials have great potential in mitigating toxic metal(loid) stress in plants. However, there are few details of nanoparticles (NPs) involved in Panax notoginseng response to cadmium (Cd) and arsenic (As). Herein, integrating physiological and metabolomic analyses, we investigated the effects of Fe₃O₄ NPs on plant growth and Cd/As responses in P. notoginseng. Cd/As treatment caused severe growth inhibition. However, foliar application of Fe₃O₄ NPs increased beneficial elements in the roots and/or leaves, decreased Cd/As content by 10.38% and 20.41% in the roots, reduced membrane damage and regulated antioxidant enzyme activity, thereby alleviating Cd/As-induced growth inhibition, as indicated by increased shoot fresh weight (FW), the rootlet length and root FW by 40.14%, 15.74%, and 46.70% under Cd stress and promoted the shoot FW by 27.00% under As toxicity. Metabolomic analysis showed that 227 and 295 differentially accumulated metabolites (DAMs) were identified, and their accumulation patterns were classified into 8 and 6 clusters in the roots and leaves, respectively. Fe₃O₄ NPs altered metabolites significantly involved in key pathways, including amino sugar and nucleotide sugar metabolism, flavonoid biosynthesis and phenylalanine metabolism, thus mediating the trade-off between plant growth and defense under stress. Interestingly, Fe₃O₄ NPs recovered more Cd/As-induced DAMs to normal levels, further supporting that Fe₃O₄ NPs positively affected seedling growth under metal(loid)s stress. In addition, Fe₃O₄ NPs altered terpenoids when the seedlings were subjected to Cd/As stress, thus affecting their potential medicinal value. This study provides insights into using nanoparticles to improve potential active ingredients of medicinal plants in metal(loid)-contaminated areas.

Keywords: Arsenic; Cadmium; Fe(3)O(4) NPs; Metabolomics; Panax notoginseng.