Novel Insights Into Manganese Toxicity Mitigation: Biogenic Calcium Phosphate Nanoparticles Boost Antioxidant Defense...

Heavy metal contamination severely impacts global food safety because of its toxicity, bioaccumulation, and nonbiodegradability. Recently developed nanotechnology strategies, including the use of greenly synthesized nanoparticles, offer environmentally safe solutions. An experiment on wheat investigated how biogenic calcium phosphate nanoparticles (CaPNPs) can improve the cellular defense against manganese toxicity. Cultivated wheat plants were irrigated with 300 μM MnSO₄ and treated with foliar spraying of biogenic CaPNPs, which were green synthesized using Jania rubens extract, at concentrations of 25, 75, and 150 mg L^-1. The 21-day-old seedlings manifested manganese (Mn) poisoning, represented by a reduction in plant height as well as weight, photosynthetic pigments, and nonenzymatic antioxidants, in addition to an escalation in the oxidative stress indicators represented by reactive oxygen species (H₂O₂) and lipid peroxidation (LPO). Furthermore, an increase in the pool of antioxidant compounds as well as antioxidant enzymes, minerals, in addition to the total antioxidant capacity, was clearly promoted by CaPNP application, especially at 75 mg L^-1, which was consistent with the control. Consequently, CaPNPs caused a significant reduction in Mn, H₂O₂, MDA, and their oxidative damage. Additionally, 75 mg L^-1 CaPNPs stimulated the expression of anti-oxidative stress responsive genes, catalase (CAT) and superoxide dismutase (SOD), in addition to betaine aldehyde dehydrogenase (BADH) and mitogen-activated protein kinases (MAPKs). Therefore, the use of biogenic 75 mg L^-1 CaPNPs as an eco-friendly nanofertilizer plays a crucial role in plants growing in Mn-contaminated soil by promoting their growth characteristics, counterbalancing oxidative damage, and provoking the activity of the antioxidant defense machinery.