Taurine enhances cadmium tolerance in maize in association with antioxidant defence and mitochondrial-related gene expression

Abstract

Cadmium (Cd) contamination in agricultural soils restricts crop productivity by disturbing cellular redox homeostasis and metabolism. The present study assessed whether taurine mitigates Cd-induced toxicity in hydroponically grown maize (Zea mays L., cv. Hido) seedlings exposed to 100 µM Cd in the presence or absence of taurine supplementation. Cd stress significantly reduced root and shoot development, pigment levels, soluble protein content, and several antioxidative enzyme activities, and was accompanied by elevated ROS accumulation and increased membrane lipid peroxidation. Taurine alleviated these effects by promoting growth recovery, maintaining pigment and protein status, and strengthening antioxidant capacity through higher SOD, CAT, APX and GR activities together with improved ascorbate–glutathione levels; this response was accompanied by lower ROS accumulation and membrane lipid peroxidation. Gene expression analysis showed that Cd exposure upregulated cytochrome c oxidase 19 (COX19) and alternative oxidase (AOX), indicating a stress-associated transcriptional response involving mitochondrial-related genes. Taurine further enhanced their expression, suggesting a taurine-associated mitochondrial-related transcriptional response under Cd stress. Taurine also significantly reduced Cd accumulation in both roots and shoots. The limited change in the translocation factor suggests that this effect was primarily associated with reduced Cd uptake, with only minor changes in root-to-shoot translocation. These findings indicate that taurine-mediated Cd tolerance involves changes in antioxidant defence, mitochondrial-related gene expression, cellular redox status, and reduced Cd accumulation.