Iron Oxide Nanoparticles as Nano-adsorbents: A Possible Way to Reduce Arsenic Phytotoxicity in Indian Mustard Plant (Brassica juncea L.)

Abstract

Application of nanoparticles (NPs) is very effective in reducing metal toxicity. The present study was designed to determine the effectiveness of iron oxide nanoparticles (Fe3O4 NP) in reducing the toxicity of arsenic in Indian mustard (Brassica juncea var. Pusa Jagannath) plant. Fourteen-day-old mustard plants were subjected to 150 µM As(III), Fe3O4 NPs (500 mg L−1 Fe3O4), 500 mg L−1 FeSO4 or As(Ш) + Fe3O4 NPs (150 µM + 500 mg L−1) stress for a period of 96 h. Significant toxicity was observed in seed germination indicators, and root–shoot length under arsenic (As) stress, but application of Fe3O4 NPs along with As improved the overall growth of plant. Results demonstrated increased photosynthetic pigment and protein content under Fe3O4 NP augmentation as compared to As-alone treatment. Antioxidative enzymes such as SOD, CAT, APX and stress-related parameters (cysteine and proline) showed varied results under different treatments. However, decreased stress-related parameters might be due to restricted entry of As inside the plant in the presence of Fe3O4 NP, and hence detoxification machinery is not required. The ameliorating effect of Fe3O4 NPs in combination with As was confirmed by reduced MDA and H2O2 content. Further, the addition of Fe3O4 NPs along with As altered sulphur-related gene transcripts. Overall, this study suggests the possible involvement of Fe3O4 NPs as nano-adsorbents in reducing As toxicity in the plant through its size variation and increase/decrease of various study parameters.