Engineered nickel oxide nanoparticles affect genome stability in Allium cepa (L.)

Abstract

Indiscriminate uses of engineered nickel oxide nanoparticles (NiO-NPs) in heavy industries have ushered their introduction into the natural environment, ensuing novel interactions with biotic components of the ecosystem. Though much is known about the toxicity of NiO-NPs on animals, their phytotoxic potential is not well elucidated. NiO-NP hinders intra-cellular homeostasis by producing ROS in excess, having profound effect on the antioxidant profile of exposed animal and plant tissues. In the present study, bulbs of the model plant Allium cepa were treated with varying concentrations of NiO-NP (10 mg L−1 - 500 mg L−1) to study changes in ROS production and potential genotoxic effect. The data generated proved a concomitant upsurge in intracellular ROS accumulation with NiO-NP dosage that could be correlated with increased genotoxicity in A. cepa. Augmented in situ ROS production was revealed through DCFH-DA assay, with highest increase in fluorescence (70% over control) in bulbs exposed to 125 mg L−1 NiO-NP. Effect of NiO-NP on genomic DNA was studied through detailed analyses of RAPD profiles which allows detection of even slightest changes in DNA sequence of treated plants. Significant differences in band intensity, loss and appearance of bands as well as genomic template stability and band sharing indices of treated plants revealed increased vulnerability of genomic DNA to NiO-NP, at even lowest concentration (10 mg L−1). This is the first report of NiO-NP induced genotoxicity on A. cepa, which confirms the nanoparticle as a potent environmental hazard.