Exogenous sorbitol-chelated calcium mitigates toxicity of cadmium in peanut seedlings through physiological, biochemical, and transcriptomic regulation

Introduction Soil cadmium (Cd) contamination is considered to be one of the adverse stresses to which plants are subject. Research has demonstrated that exogenous calcium plays a crucial role in plant stress resistance. Methods Here, a controlled comparative experiment was conducted using peanut seedlings ( Arachis hypogaea L.) exposed to Cd stress and supplied with either inorganic calcium or sorbitol-chelated calcium (SCC) at an equivalent calcium (Ca) concentration. This investigation was undertaken through integrated physiological, biochemical and transcriptomic analyses. Results In the context of Cd stress, a marked inhibition in the growth parameters, photosynthetic activity, and root architecture of peanut seedlings was observed. This inhibition resulted in a significant accumulation of reactive oxygen species (ROS) within the plants. The application of exogenous calcium has been demonstrated to effectively alleviate Cd toxicity, with SCC exhibiting particularly notable efficacy in this regard. In comparison with Cd treatment, SCC significantly improved plant growth parameters and photosynthetic efficiency. Furthermore, SCC significantly enhanced superoxide dismutase (SOD) activity in tissues while concomitantly reducing malondialdehyde (MDA) and ROS levels, thereby mitigating membrane lipid oxidation. Concurrently, the analysis revealed that the SCC samples exhibited an upregulation of key genes, including AUX/IAA, GH3, SAUR, and JAZ. These genes have been implicated in promoting root growth and activating defence-related hormone pathways. Structural equation modelling further indicated that chlorophyll fluorescence exerted a significant positive influence on biomass accumulation, while excessive reactive oxygen species and osmotic regulators served as major inhibitory factors. Discussion Consequently, SCC effectively mitigates Cd toxicity by stabilising photosynthetic systems, enhancing antioxidant defences, and regulating hormonal signalling, thereby promoting recovery of peanut seedling growth. The present study offers novel insights and a scientific basis for the efficient utilisation of Ca-containing fertilisers and the mitigation of heavy metal pollution in agricultural fields.