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

Application of nanoparticles (NPs) is very effective in reducing metal toxicity. The present study was designed to determine the effectiveness of iron oxide nanoparticles (Fe 3 O 4 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), Fe 3 O 4 NPs (500 mg L −1 Fe 3 O 4 ), 500 mg L −1 FeSO 4 or As(Ш) + Fe 3 O 4 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 Fe 3 O 4 NPs along with As improved the overall growth of plant. Results demonstrated increased photosynthetic pigment and protein content under Fe 3 O 4 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 Fe 3 O 4 NP, and hence detoxification machinery is not required. The ameliorating effect of Fe 3 O 4 NPs in combination with As was confirmed by reduced MDA and H 2 O 2 content. Further, the addition of Fe 3 O 4 NPs along with As altered sulphur-related gene transcripts. Overall, this study suggests the possible involvement of Fe 3 O 4 NPs as nano-adsorbents in reducing As toxicity in the plant through its size variation and increase/decrease of various study parameters.