TiO2-nanoparticles (TiO2-NP) have the potential to impair plant development. Nevertheless, the metabolic processes behind the physiological responses to TiO2-NP are still far from being fully understood. In this study, Triticum aestivum plants were exposed for 21 days to different concentrations (0; 5; 50; 150 mg L-1) of TiO2-NP (P25). After treatment, the metabolite profiles of roots and leaves were analysed. The content of >70 % of the identified metabolites changed in response to P25 and the impact on metabolic pathways increased with TiO2-NP dose, with leaves showing higher alterations. Roots up-regulated monosaccharides, azelaic acid, and γ-aminobutanoic acid and triggered the tyrosine metabolism, whereas leaves up-regulated the metabolisms of reserve sugars and tocopherol, and the phenylalanine and tryptophan pathways. Both organs (mainly leaves) up-regulated the aspartate family pathway together with serine, alanine and valine metabolisms and the glycerolipids' biosynthesis. In addition, the citrate and glyoxylate metabolisms were down-regulated in both organs (highest dose). Sugar biosynthesis breakdown, due to photosynthetic disturbances, shifted the cell metabolism to use amino acids as an alternative energy source, and both ROS and sugars worked as signalling molecules activating organ dependent antioxidant responses. Concluding, these NP-pollutants severely impact multiple crop metabolic pathways and may ultimately compromise plant performance.
Keywords: Metabolic pathways; Metabolomics; Nanomaterials; Phytotoxicity; Titanium dioxide.
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