Ascorbate Supplementation: A Blessing in Disguise for Tomato Seedlings Exposed to NiO Nanoparticles

Abstract

While nanomaterials offer wide-ranging solutions, their intensified use causes environmental contamination, posing ecotoxicological risks to several organisms, including plants. It becomes important to understand the phytotoxicity of NMs and find sustainable strategies to enhance plant tolerance to these emerging contaminants. Thus, this study aimed to evaluate the potential of ascorbic acid (AsA) in increasing the tolerance of in vitro grown tomato seedlings to nickel oxide nanomaterials (nano-NiO). Seeds of Solanum lycopersicum cv. Micro-Tom were germinated in culture medium containing 30 mg/L nano-NiO, 150 mg/L AsA, or a combination of both. A control situation was included. Surprisingly, single AsA administration in the medium impaired the growth of tomato seedlings and increased the lipid peroxidation of biomembranes. Nonetheless, plant development was more severely repressed by nano-NiO, with evident macroscopic effects that did not translate into serious redox disorders. Still, proline and AsA levels diminished in response to nano-NiO, while glutathione and phenols increased. Despite the negative effects of AsA on non-stressed plants, nano-NiO-induced stress was counteracted by AsA supply, with enhanced levels of glutathione and phenols. Overall, the supplementation with AsA proved to be a “blessing in disguise” for plants under nano-NiO-induced stress, improving antioxidant capacity and activating other defense mechanisms.