The role of exogenous silicon to mitigate Al2O3 nanoparticle-induced toxicity in barley (Hordeum vulgare L.)

Abstract

In this study, we used silicon (Si, in the form of K2SiO3, 2 mM) to alleviate the toxicity of aluminum oxide (Al2O3) nanoparticles (NPs) in barley (Hordeum vulgare L.). Using Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS) analyses, we showed that the Al2O3 NPs were taken up by barley plants. Barley growth was negatively affected by the addition of 3 g l-1 nano-Al2O3, whereas the diminishing effect of NPs on barley growth was not obvious when 1 g l-1 nano-Al2O3 was applied, indicating that the nano-Al2O3 action is dependent on nano-Al2O3 dose. Si pretreatment ameliorated toxic effects of high nano-Al2O3 on root growth. Si pretreatment did not decrease nano-Al2O3 entry into roots but reduced nano-Al2O3 accumulation in the shoot. The restriction of the root-to-shoot translocation of nano-Al2O3 was one of the important mechanisms for Si to mitigate high nano-Al2O3 toxicity. The occurrence of oxidative stress was found under 3 g l1 nano-Al2O3 treatment, as evaluated by the accumulation of malondialdehyde (MDA). Exogenous addition of Si could alleviate toxicity symptoms induced by Al2O3 nanoparticles by reducing lipid peroxidation via enhancing antioxidant activity of catalase as well as by limiting the root-to-shoot translocation of nano-Al2O3. These data provide the first direct evidence that the Si pretreatment ameliorates nano Al2O3 phytotoxicity in plants.

Keywords

• Hordeum vulgare L.
• malondialdehyde
• nano-Al2O3
• nanotoxicity
• silicon