title: Comparative impacts of iron oxide nanoparticles and ferric ions on the growth of Citrus maxima.
abstract: The impacts of iron oxide nanoparticles (γ-Fe2O3NPs) 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-Fe2O3NPs and Fe3+. We found that γ-Fe2O3NPs could enter plant roots but no translocation from roots to shoots was observed. 20 mg/L γ-Fe2O3NPs had no impact on plant growth. 50 mg/L γ-Fe2O3NPs significantly enhanced chlorophyll content by 23.2% and root activity by 23.8% as compared with control. However, 100 mg/L γ-Fe2O3NPs 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-Fe2O3NPs, especially for 100 mg/L Fe3+. The impacts caused by γ-Fe2O3NPs and Fe3+were concentration-dependent. Physiological results showed that γ-Fe2O3NPs at proper concentrations had the potential to be an effective iron nanofertilizer for plant growth. RT-PCR analysis showed that γ-Fe2O3NPs had no impact on AHA gene expression. 50 mg/L γ-Fe2O3NPs 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-Fe2O3NPs and Fe3+were significantly lower than control, indicating that all γ-Fe2O3NPs and Fe3+treatments could supply iron to C. maxima seedlings. Overall, plants can modify the speciation and transport of γ-Fe2O3NPs or Fe3+for self-protection and development by activating many physiological and molecular processes.
authors.affiliation: School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Hu
authors.affiliation: Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, United States.
authors.forename: Huiyuan
authors.initials: H
authors.lastname: Guo
authors.affiliation: School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China; Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, United States. Electronic address: lijunli0424@sina.com.
authors.forename: Junli
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China.
authors.forename: Qiuliang
authors.initials: Q
authors.lastname: Gan
authors.affiliation: Institute of Economic Crops, Hubei Academy of Agricultural Science, Wuhan 430064, PR China.
authors.forename: Yunqiang
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, United States.
authors.forename: Baoshan
authors.initials: B
authors.lastname: Xing
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D002957:Citrus / Q000187:drug effects* / Q000254:growth & development; D005290:Ferric Compounds / Q000378:metabolism / Q000633:toxicity*; D007477:Ions; D053758:Nanoparticles / Q000633:toxicity*; D018517:Plant Roots / Q000378:metabolism; D036226:Seedlings / Q000378:metabolism; D012989:Soil Pollutants / Q000633:toxicity*
chemical_list: D005290:Ferric Compounds; D007477:Ions; D012989:Soil Pollutants; D002734:Chlorophyll; C000499:ferric oxide
keywords: Citrus maxima; Fe(3+); Gene expression; Impacts; Micronutrient; γ-Fe(2)O(3) NPs