Li Junli, Hu Jing, Ma Chuanxin, Wang Yunqiang, Wu Chan, Huang Jin, Xing Baoshan
School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, PR China.
Stockbridge School of Agriculture, University of Massachusetts, Amherst, MA 01003, United States.
Chemosphere. 2016 Sep;159:326-334. doi: 10.1016/j.chemosphere.2016.05.083. Epub 2016 Jun 15.
Iron oxide nanoparticles (γ-Fe2O3 NPs) have emerged as an innovative and promising method of iron application in agricultural systems. However, the possible toxicity of γ-Fe2O3 NPs and its uptake and translocation require further study prior to large-scale field application. In this study, we investigated uptake and distribution of γ-Fe2O3 NPs in corn (Zea mays L.) and its impacts on seed germination, antioxidant enzyme activity, malondialdehyde (MDA) content, and chlorophyll content were determined. 20 mg/L of γ-Fe2O3 NPs significantly promoted root elongation by 11.5%, and increased germination index and vigor index by 27.2% and 39.6%, respectively. However, 50 and 100 mg/L γ-Fe2O3 NPs remarkably decreased root length by 13.5% and 12.5%, respectively. Additionally, evidence for γ-Fe2O3 NPs induced oxidative stress was exclusively found in the root. Exposures of different concentrations of NPs induced notably high levels of MDA in corn roots, and the MDA levels of corn roots treated by γ-Fe2O3 NPs (20-100 mg/L) were 5-7-fold higher than that observed in the control plants. Meanwhile, the chlorophyll contents were decreased by 11.6%, 39.9% and 19.6%, respectively, upon NPs treatment relative to the control group. Images from fluorescence and transmission electron microscopy (TEM) indicated that γ-Fe2O3 NPs could enter plant roots and migrate apoplastically from the epidermis to the endodermis and accumulate the vacuole. Furthermore, we found that NPs mostly existed around the epidermis of root and no translocation of NPs from roots to shoots was observed. Our results will be highly meaningful on understanding the fate and physiological effects of γ-Fe2O3 NPs in plants.
氧化铁纳米颗粒（γ-Fe2O3 NPs）已成为农业系统中铁应用的一种创新且有前景的方法。然而，在大规模田间应用之前，γ-Fe2O3 NPs的潜在毒性及其吸收和转运需要进一步研究。在本研究中，我们调查了γ-Fe2O3 NPs在玉米（Zea mays L.）中的吸收和分布，并测定了其对种子萌发、抗氧化酶活性、丙二醛（MDA）含量和叶绿素含量的影响。20 mg/L的γ-Fe2O3 NPs显著促进根伸长11.5%，并分别使发芽指数和活力指数提高27.2%和39.6%。然而，50和100 mg/L的γ-Fe2O3 NPs分别使根长度显著降低13.5%和12.5%。此外，仅在根中发现了γ-Fe2O3 NPs诱导氧化应激的证据。不同浓度的纳米颗粒处理显著诱导玉米根中高水平的MDA，γ-Fe2O3 NPs（20 - 100 mg/L）处理的玉米根中MDA水平比对照植物中观察到的高5 - 7倍。同时，与对照组相比，纳米颗粒处理后叶绿素含量分别降低了11.6%、39.9%和19.6%。荧光和透射电子显微镜（TEM）图像表明，γ-Fe2O3 NPs可以进入植物根，并从表皮向质外体迁移至内皮层并积累在液泡中。此外，我们发现纳米颗粒大多存在于根表皮周围，未观察到纳米颗粒从根向地上部的转运。我们的结果对于理解γ-Fe2O3 NPs在植物中的归宿和生理效应具有重要意义。
