Ion flux integrated with transcriptomic and metabolomics analysis uncover molybdenum mitigation on cadmium toxicity in clove basil seedlings.

Abstract

Both preventing cadmium (Cd) from entering the food system and maximizing the utility of Cd-contaminated soils are of paramount importance. This study investigated the mitigation of Cd²⁺ toxicity in clove basil seedlings, an aromatic plant producing essential oil, by molybdenum (Mo) supplementation. The results revealed a distinct, Mo-mediated defense mechanism. First, phenotypic assessments showed that exogenous Mo application (0.08 μM) restored Cd-inhibited seedling growth, increasing whole-plant fresh weight by 37.62%. Concurrently, Mo application reduced Cd²⁺ levels by at least 8.31% and suppressed net Cd²⁺ translocation from roots to shoots. Second, transcriptomic analysis integrating WGCNA and GSEA revealed that Cd + Mo combination treatment induced lipid biosynthesis pathways while retarding detrimental lipid metabolism. These results were corroborated by metabolomics analysis, which showed that the most altered metabolites by Cd + Mo were lipids. Third, physiological measurements demonstrated that Cd + Mo enhanced the antioxidant activity. Specifically, glutathione reductase activity and glutathione content increased by 112.07% and 17.79%, respectively, while glutathione peroxidase activity was reduced by 92.18%. Mechanistically, multi-omics and physiological analyses highlighted that Mo mitigated Cd²⁺ toxicity primarily by reducing Cd²⁺ uptake, enhancing antioxidant activity, and modulating lipid metabolism. Therefore, this study provides critical mechanistic insights into Mo-mediated Cd tolerance, offering a significant contribution to the field by establishing a highly practical paradigm for both phytoremediation and safe land utilization. Cultivating non-food economic crops, such as clove basil, potentially represents an effective strategy for safely utilizing heavy metal-contaminated land.