Comparative impacts of iron oxide nanoparticles and ferric ions on the growth of Citrus maxima.

Abstract

The impacts of iron oxide nanoparticles (γ-Fe2O3 NPs) and ferric ions (Fe3+) on plant growth and molecular responses associated with the transformation and transport of Fe2+ were poorly understood. This study comprehensively compared and evaluated the physiological and molecular changes of Citrus maxima plants as affected by different levels of γ-Fe2O3 NPs and Fe3+. We found that γ-Fe2O3 NPs could enter plant roots but no translocation from roots to shoots was observed. 20 mg/L γ-Fe2O3 NPs had no impact on plant growth. 50 mg/L γ-Fe2O3 NPs significantly enhanced chlorophyll content by 23.2% and root activity by 23.8% as compared with control. However, 100 mg/L γ-Fe2O3 NPs notably increased MDA formation, decreased chlorophyll content and root activity. Although Fe3+ ions could be used by plants and promoted the synthesis of chlorophyll, they appeared to be more toxic than γ-Fe2O3 NPs, especially for 100 mg/L Fe3+. The impacts caused by γ-Fe2O3 NPs and Fe3+ were concentration-dependent. Physiological results showed that γ-Fe2O3 NPs at proper concentrations had the potential to be an effective iron nanofertilizer for plant growth. RT-PCR analysis showed that γ-Fe2O3 NPs had no impact on AHA gene expression. 50 mg/L γ-Fe2O3 NPs and Fe3+ significantly increased expression levels of FRO2 gene and correspondingly had a higher ferric reductase activity compared to both control and Fe(II)-EDTA exposure, thus promoting the iron transformation and enhancing the tolerance of plants to iron deficiency. Relative levels of Nramp3 gene expression exposed to γ-Fe2O3 NPs and Fe3+ were significantly lower than control, indicating that all γ-Fe2O3 NPs and Fe3+ treatments could supply iron to C. maxima seedlings. Overall, plants can modify the speciation and transport of γ-Fe2O3 NPs or Fe3+ for self-protection and development by activating many physiological and molecular processes.

• Authors: Jing Hu, Huiyuan Guo, Junli Li, Qiuliang Gan, Yunqiang Wang, Baoshan Xing
• Journal: Environmental pollution (Barking, Essex : 1987) (Environ Pollut) Vol. 221 Pg. 199-208 (Feb 2017) ISSN: 1873-6424 [Electronic] England
• PMID: 27916492 (Publication Type: Journal Article)
• Copyright: Copyright © 2016 Elsevier Ltd. All rights reserved.

Chemical References

• Ferric Compounds
• Ions
• Soil Pollutants
• Chlorophyll
• ferric oxide

Topics

• Chlorophyll (metabolism)
• Citrus (drug effects, growth & development)
• Ferric Compounds (metabolism, toxicity)
• Ions
• Nanoparticles (toxicity)
• Plant Roots (metabolism)
• Seedlings (metabolism)
• Soil Pollutants (toxicity)