Phytotoxic effects of silver nanoparticles in tobacco plants

The small size of nanoparticles (NPs), with dimensions between 1 and 100 nm, results in unique chemical and physicalcharacteristics, which is why they are implemented in various consumer products. Therefore, an important concern is thepotential detrimental impact of NPs on the environment. As plants are a vital part of ecosystem, investigation of the phytotoxiceffects of NPs is particularly interesting. This study investigated the potential phytotoxicity of silver nanoparticles (AgNPs) ontobacco (Nicotiana tabacum) plants and compared it with the effects of the same AgNO3 concentrations. Accumulation of silverin roots and leaves was equally efficient after both AgNP and AgNO3 treatment, with predominant Ag levels found in the roots.Exposure to AgNPs did not result in elevated values of oxidative stress parameters either in roots or in leaves, while AgNO3induced oxidative stress in both plant tissues. In the presence of both AgNPs and AgNO3, root meristem cells became highlyvacuolated, which indicates that vacuoles might be the primary storage target for accumulated Ag. Direct AgNP uptake by rootcells was confirmed. Leaf ultrastructural studies revealed changes mainly in the size of chloroplasts of AgNP-treated and AgNO3-treated plants. All of these findings indicate that nano form of silver is less toxic to tobacco plants than silver ions.