Zinc uptake from ZnSO4 (aq) and Zn-EDTA (aq) and its root-to-shoot transport in soybean plants (Glycine max) probed by time-resolved in vivo X-ray spectroscopy.

This study investigated the dynamic of zinc (Zn) uptake and the root-to-shoot Zn-transport when supplied as ZnSO4 (aq) or Zn-EDTA (aq) in soybean seedlings using in vivo X-ray fluorescence (XRF) and X-ray absorption spectroscopy (XANES). The time-resolved X-ray fluorescence showed that plants absorbed ca. 10-fold more Zn from ZnSO4 (aq) than from Zn-EDTA (aq). However, the uptake velocity did not influence the amount of Zn in the stem. It let furthermore appear that the plants were able to reduce the absorption of Zn from Zn-EDTA (aq) earlier than ZnSO4 (aq). Thus, the entrance of Zn2+ into the roots is not necessarily accompanied by SO42-(aq). Regardless the source, the Zn distribution and its transport in the stem were spatially correlated to the bundles and cortex nearby the epidermal cells. Its chemical speciation showed that Zn is neither transported as ZnSO4(aq) nor as Zn-EDTA(aq), indicating that these compounds are retained in the roots or biotransformed on in the root-solution interface. Zn2+ was long-distance transported complexed by organic molecules such as histidine, malate, and citrate, and the proportion of ligands was affected by the concentration of Zn2+ in the stem rather than by the type of Zn source.

A new glance on root-to-shoot in vivo zinc transport and time-dependent physiological effects of ZnSO4 and ZnO nanoparticles on plants.

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 ZnSO4(aq) (100 and 1000 mg Zn L-1) 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 Zn3(PO4)2 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-1, 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-1 ZnSO4(aq). 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.

Bean Seedling Growth Enhancement Using Magnetite Nanoparticles.

Advanced fertilizers are one of the top requirements to address rising global food demand. This study investigates the effect of bare and polyethylene glycol-coated Fe3O4 nanoparticles on the germination and seedling development of Phaseolus vulgaris L. Although the germination rate was not affected by the treatments (1 to 1 000 mg Fe L-1), seed soaking in Fe3O4-PEG at 1 000 mg Fe L-1 increased radicle elongation (8.1 ± 1.1 cm vs 5.9 ± 1.0 cm for the control). Conversely, Fe2+/Fe3+(aq) and bare Fe3O4 at 1 000 mg Fe L-1 prevented the growth. X-ray spectroscopy and tomography showed that Fe penetrated in the seed. Enzymatic assays showed that Fe3O4-PEG was the least harmful treatment to α-amylase. The growth promoted by the Fe3O4-PEG might be related to water uptake enhancement induced by the PEG coating. These results show the potential of using coated iron nanoparticles to enhance the growth of common food crops.

X-ray Spectroscopy Uncovering the Effects of Cu Based Nanoparticle Concentration and Structure on Phaseolus vulgaris Germination and Seedling Development.

Nanoparticles properties such as solubility, tunable surface charges, and singular reactivity might be explored to improve the performance of fertilizers. Nevertheless, these unique properties may also bring risks to the environment since the fate of nanoparticles is poorly understood. This study investigated the impact of a range of CuO nanoparticles sizes and concentrations on the germination and seedling development of Phaseolus vulgaris L. Nanoparticles did not affect seed germination, but seedling weight gain was promoted by 100 mg Cu L-1 and inhibited by 1 000 mg Cu L-1 of 25 nm CuO and CuSO4. Most of the Cu taken up remained in the seed coat with Cu hotspots in the hilum. X-ray absorption spectroscopy unraveled that most of the Cu remained in its pristine form. The higher surface reactivity of the 25 nm CuO nanoparticles might be responsible for its deleterious effects. The present study therefore highlights the importance of the nanoparticle structure for its physiological impacts.