Integrated proteomic, chemical forms, and distribution analysis reveals NaCl-mediated detoxification of cadmium in...

NaCl up-regulates ion transporters to accelerate Na and Cd to the shoots and Cd into vacuoles, shifts intracellular homeostasis to lower Cd toxicity, and promotes YCF1/2-driven photosynthesis for faster organic-mass accumulation to relieve Cd stress. Due to the rapid development of industry and agriculture, heavy metals (HMs) pollution in saline soil has become increasingly severe. Suaeda salsa is a promising candidate for the phytoremediation of HMs in saline soils. In this study, we identified a pathway by which high salt concentrations enhance cadmium (Cd) tolerance in S. salsa. The results indicated that NaCl improved resistance to Cd by modulating the levels of proline and carbohydrates, particularly in the range of 100 to 200 mM NaCl. Roots, the main sink for Cd²⁺, immobilize the ion in the cell wall through cytoplasmic pathways and block its transmembrane transport. Moreover, NaCl significantly increased the Cd content in the cell wall while decreasing Cd accumulation in organelles and the soluble fraction. Notably, 100 and 150 mM NaCl were more effective in promoting the transport of Cd from roots to leaves, helping to alleviate Cd toxicity in Suaeda salsa. Furthermore, NaCl induced the transformation of Cd into a less toxic form, which was associated with higher water transport capacity and increased ion transportation-related proteins. Proteomic analysis indicated that under Cd stress, NaCl may maintain cellular osmotic homeostasis by up-regulating SOS1, NHX1 and HKT1, and may enhance the adaptability of plants to abiotic stress by up-regulating YCF1 and YCF2. Additionally, NaCl may maintain the reduction state of glutathione (GSH) by up-regulating CSD2 and PRXQ, which indirectly affects the chelation of HMs. This study may provide a sustainable approach for phytoremediation of HMs contaminated saline soil.