Titanium dioxide nanoparticles seed priming as a remedy for nickel-induced stress in maize through antioxidant enhancement and ultrastructural optimization.

Heavy metals (HMs) have emerged as a critical global concern, not only limiting crop productivity but also posing risks to public health. Among them, nickel (Ni) is an essential micronutrient for plant growth; however, it becomes toxic at higher concentrations. Nano-enabled approaches, on the other hand, have emerged as promising eco-friendly alternatives for mitigating the negative impact associated with HMs. Here, we investigated the potential of titanium dioxide nanoparticles (TiO NPs) against Ni-induced stress in maize. Our results showed that Ni stress caused negative changes in maize by the excessive production of reactive oxygen species (ROS), inhibiting photosynthetic attributes, and damaging cellular ultrastructure. In contrast, TiO NPs priming significantly enhanced the antioxidant mechanism, photosynthetic efficacy, and nutrient uptake while reducing ultrastructural damage caused by Ni stress. Furthermore, TiO NPs efficiently reduced Ni accumulation, MDA (28%/32%), HO (23%/26%), and O (31%/34%) levels in shoot/root tissues, respectively, compared to Ni treatment. Moreover, TiO NPs priming has modulated the expression of antioxidant and defense-related genes, thereby restoring cellular redox homeostasis. Collectively, this is the first piece of evidence demonstrating the potential of TiO NPs as an efficient and sustainable alternative for enhancing crop tolerance in Ni-contaminated areas.