Rhizospheric regulation and antioxidative defense mediate species-specific phytoremediation efficiency in multi-metal contaminated soils

release and rhizospheric alkalization, which reduced metal solubility and availability. At the physiological level, all species experienced metal-induced oxidative stress, evidenced by elevated root malondialdehyde (MDA) concentrations. However, shoot responses diverged markedly: B. pilosa maintained oxidative homeostasis with stable shoot MDA levels, while C. argentea and M. sativa showed progressive oxidative burden. Metallothionein-based detoxification strategies also varied tissue and species specifically. Root tissues generally upregulated glutathione (GSH) and phytochelatin (PC) biosynthesis, yet foliar responses differed: GSH predominated in B. pilosa leaves, whereas PCs dominated in C. argentea and M. sativa. Antioxidant enzyme profiles further distinguished species strategies: B. pilosa and C. argentea showed coordinated catalase (CAT) and peroxidase (POD) upregulation in shoots, while M. sativa exhibited enzymatic imbalances indicative of compromised oxidative defense. These findings establish a mechanistic framework linking rhizosphere modification, metal translocation efficiency, and antioxidative capacity, providing critical insights for rational plant selection in tailored phytoremediation programs targeting multi-metal contaminated environments.