Cadmium tolerance mechanisms and the regulatory role of GST gene in genetically related wheat varieties under Cd stress: A multi-level analysis.

Cadmium (Cd) contamination poses a serious threat to wheat production and food safety. This study investigated Cd tolerance mechanisms at morpho-physiological, biochemical, and transcriptomic levels in three genetically related wheat genotypes exposed to 10 μM Cd stress. Cd exposure inhibited plant growth in all genotypes, but the hybrid cultivar L4 (Luomai 49) exhibited lower growth inhibition and greater Cd tolerance than its parental lines L6 (Luomai 6010) and ZM (Zhengmai 9023). L4 maintained improved root system architecture, lower oxidative damage, and more stable redox homeostasis, while restricting Cd translocation from roots to shoots. Transcriptomic analysis revealed extensive genotype-dependent transcriptional reprogramming in L4, with Cd-responsive genes enriched in antioxidant regulation, cell wall modification, transmembrane transport, and phytohormone signaling processes. Glutathione S-transferase (GST) genes were identified as important Cd-responsive candidates and exhibited enhanced transcriptional responses in L4. Functional validation using TaGST mutant plants demonstrated that disruption of TaGST function reduced Cd tolerance, impaired plant growth, altered elemental homeostasis, and disrupted stress-responsive transcriptional networks associated with antioxidant defense and secondary metabolism. Collectively, these findings demonstrate that L4 achieves enhanced Cd tolerance through coordinated physiological and transcriptional regulation and reveal a positive role of GST in wheat Cd stress adaptation, providing potential genetic resources for breeding Cd-tolerant wheat cultivars.