University of São Paulo, Nuclear Instrumentation Laboratory, Center for Nuclear Energy in Agriculture, Piracicaba, 13416000, Brazil.
University of São Paulo, Cellular and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture, Piracicaba, 13416000, Brazil.
Sci Rep. 2019 Jul 18;9(1):10416. doi: 10.1038/s41598-019-46796-3.
Understanding nanoparticle root uptake and root-to-shoot transport might contribute to the use of nanotechnology in plant nutrition. This study performed time resolved experiments to probe Zn uptake, biotransformation and physiological effects on Phaseolus vulgaris (L.). Plants roots were exposed to ZnO nanoparticles (40 and 300 nm) dispersions and ZnSO (100 and 1000 mg Zn L) for 48 h. Near edge X-ray absorption spectroscopy showed that 40 nm ZnO was more easily dissolved by roots than 300 nm ZnO. It also showed that in the leaves Zn was found as a mixture Zn(PO) and Zn-histidine complex. X-ray fluorescence spectroscopy showed that root-to-shoot Zn-translocation presented a decreasing gradient of concentration and velocity, it seems radial Zn movement occurs simultaneously to the axial xylem transport. Below 100 mg Zn L, the lower stem tissue section served as a buffer preventing Zn from reaching the leaves. Conversely, it was not observed for 1000 mg Zn L ZnSO. Transcriptional analysis of genes encoding metal carriers indicated higher expression levels of tonoplast-localized transporters, suggesting that the mechanism trend to accumulate Zn in the lower tissues may be associated with an enhanced of Zn compartmentalization in vacuoles. The photosynthetic rate, transpiration, and water conductance were impaired by treatments.
了解纳米颗粒的根部吸收和根到梢的运输可能有助于将纳米技术应用于植物营养。本研究进行了时间分辨实验，以探究 Zn 的吸收、生物转化和对菜豆（Phaseolus vulgaris（L.））的生理影响。将植物根部暴露于 ZnO 纳米颗粒（40 和 300nm）分散体和 ZnSO（100 和 1000mg Zn L）中 48 小时。近边 X 射线吸收光谱表明，40nm ZnO 比 300nm ZnO 更容易被根部溶解。它还表明，在叶片中发现 Zn 作为 Zn(PO)和 Zn-组氨酸复合物的混合物。X 射线荧光光谱表明，Zn 从根部到梢部的转运呈现出浓度和速度的递减梯度，似乎径向 Zn 运动与轴向木质部运输同时发生。在 100mg Zn L 以下，较低的茎组织部分充当缓冲液，防止 Zn 到达叶片。相反，在 1000mg Zn L ZnSO 中则没有观察到这种情况。编码金属载体的基因的转录分析表明，液泡膜定位转运蛋白的表达水平较高，表明将 Zn 积累在较低组织中的机制趋势可能与液泡中 Zn 的区室化增强有关。处理后，光合速率、蒸腾和水分传导受到损害。
