Data on the interaction of hyperaccumulating plants with nanoscale metals Zn and Cd.

The article describes: growth phenotypes of the four plant species (Noccaea caerulescens, Thlaspi perfoliatum, Arabidopsis halleri, Arabidopsis thaliana) before and after the treatment with ionic and nanoscale Zn and Cd (Fig. 1); the method of synthesis and characterization of ZnS QDs and CdS QDs (Fig. 2); the genetic characterization (performed with molecular markers) of the four plant species, their relative genecological relation (Fig. 3); a conceptual workflow designed to detect the amount of ionic Zn and Cd in the original solution/suspension used for the treatment (Fig. 4); the determination of Zn and Cd in the treatment soils after 30 days from supplement of ionic and nanoscale Zn and Cd (Fig. 5); the effect of the treatment on root elongation (Fig. 6); a workflow of a novel analytical method designed to detect the ionic and nanoscale Zn and Cd in the plant tissues after digestion with three different methods (Fig. 7); a reconstruction experiments with an exsiccated powder of plant tissue spiked with the same amount of Zn in the ionic and nanoscale forms (Fig. 8); a TEM-EDX analysis on these powdered plant tissues after removal of all soluble (ionic) Zn to show the presence of Zn in a non soluble form (nanoscale) (Fig. 9); the calculation of Bioconcentration Factor (BCF) and Translocation Factor (TF) and their ratios (Table 1); all data of the "spiking" experiments (Tables 2 and 3).

Interaction of hyperaccumulating plants with Zn and Cd nanoparticles.

Metal hyperaccumulating plant species are an interesting example of natural selection and environmental adaptation but they may also be useful to developing new technologies of environmental monitoring and remediation. Noccaea caerulescens and Arabidopsis halleri are both Brassicaceae and are known metal hyperaccumulators. This study evaluated tolerance, uptake and translocation of zinc sulfide quantum dots by N. cearulescens and cadmium sulfide quantum dots by A. halleri in direct comparison with the non-hyperaccumulator, genetically similar T. perfoliatum and A. thaliana. Growth media were supplied with two different concentrations of metal in either salt (ZnSO4 and CdSO4) or nanoscale form (ZnS QDs and CdS QDs). After 30 days of exposure, the concentration of metals in the soil, roots and leaves was determined. Uptake and localization of the metal in both nanoscale and non-nanoscale form inside plant tissues was investigated by Environmental Scanning Electron Microscopy (ESEM) equipped with an X-ray probe. Specifically, the hyperaccumulators in comparison with the non-hyperaccumulators accumulate ionic and nanoscale Zn and Cd in the aerial parts with a BCF ratio of 45.9 for Zn ion, 49.6 for nanoscale Zn, 2.64 for Cd ion and 2.54 for nanoscale Cd. Results obtained with a differential extraction analytical procedure also showed that a significant fraction of nanoscale metals remained inside the plants in a form compatible with the retention of at least a partial initial structure. The molecular consequences of the hyperaccumulation of nanoscale materials are discussed considering data obtained with hyperaccumulation of ionic metal. This is the first report of conventional hyperaccumulating plants demonstrating an ability to hyperaccumulate also engineered nanomaterials (ENMs) and suggests a potential novel strategy for not only understanding plant-nanomaterial interactions but also for potential biomonitoring in the environment to avoid their entering into the food chains.

Cadmium sulfide quantum dots impact Arabidopsis thaliana physiology and morphology.

The differential mechanisms of CdS QDs (Quantum Dots) and Cd ion toxicity to Arabidopsis thaliana (L.) Heynh were investigated. Plants were exposed to 40 and 60 mg L-1 for CdS QDs and 76.9 and 115.2 mg L-1 CdSO4·7H2O and toxicity was evaluated at 5, 20, 35 (T5, T20, T35) days after exposure. Oxidative stress upon exposure was evaluated by biochemical essays targeting non-enzymatic oxidative stress physiological parameters, including respiration efficiency, total chlorophylls, carotenoids, ABTS and DPPH radicals reduction, total phenolics, GSH redox state, lipid peroxidation. Total Cd in plants was measured with AAS. Root and leaf morphology and element content were assessed in vivo utilizing low-vacuum Environmental Scanning Electron Microscopy (ESEM) with X-ray microanalysis (EDX). This integrated approach allowed identification of unique nanoscale CdS QDs toxicity to the plants that was distinct from CdSO4 exposure. The analyses highlighted that CdS QDs and Cd ions effects are modulated by the developmental stage of the plant, starting from T20 till T35 the plant development was modulated by the treatments, in particular CdS QDs induced early flowering. Both treatments induced Fe accumulation in roots, but at different intensities, while CdS QDs was associated with Mn increase into plant leaf. CdSO4 elicited higher levels of oxidative stress compared with QDs, especially the former treatment caused more intense respiration damages and reduction in chlorophyll and carotenoids than the latter. The two types of treatments impact differently on root and leaf morphology.

Structural and Functional Features of Chars From Different Biomasses as Potential Plant Amendments.

Biochars result from the pyrolysis of biomass waste of plant and animal origin. The interest in these materials stems from their potential for improving soil quality due to increased microporosity, carbon pool, water retention, and their active capacity for metal adsorption from soil and irrigation water. Applications in agriculture have been studied under different conditions, but the overall results are still unclear. Char structure, which varies widely according to the pyrolysis process and the nature of feedstock, is thought to be a major factor in the interaction of chars with soil and their metal ion adsorption/chelation properties. Furthermore, biochar nutrients and their elemental content can modify soil fertility. Therefore, the use of biochars in agricultural settings should be examined carefully by conducting experimental trials. Three key problems encountered in the use of biochar involve (i) optimizing pyrolysis for biomass conversion into energy and biochar, (ii) physicochemically characterizing biochar, and (iii) identifying the best possible conditions for biochar use in soil improvement. To investigate these issues, two types of wood pellets, plus digestate and poultry litter, were separately converted into biochar using different technologies: pyrolysis/pyrogasification or catalytic (thermo)reforming. The following physicochemical features for the different biochar batches were measured: pH, conductivity, bulk density, humidity and ash content, particle size, total organic substances, and trace element concentrations. Fine porous structure analysis and total elemental analysis were performed using environmental scanning electron microscopy along with energy-dispersive X-ray spectrometry (EDX). Phytotoxicity tests were performed for each biochar. Finally, we were able to (i) differentiate the biochars according to their physicochemical properties, microstructure, elemental contents, and original raw biomass; (ii) correlate the whole biochar features with their respective optimal concentrations when used as plant fertilizers or soil improvers; and (iii) show that biochars from animal origin were phytotoxic at lower concentrations than those from plant feedstock.

Abiotic Stress Response to As and As+Si, Composite Reprogramming of Fruit Metabolites in Tomato Cultivars.

The toxic element arsenic interacts with the beneficial element silicon at many levels of the plant metabolism. The ability of the tomato plant to take up and translocate As into its fruit has risen concerns that it could facilitate the entry of this element into the human food chain above the admitted level. Here, the fruit of two contrasting tomato cultivars, Aragon and Gladis, were evaluated following exposures of either 48 h or 14 days to As-contaminated irrigation water, with or without supplementary Si. The focus was on selected biochemical stress response indicators to dissect metabolic fruit reprogramming induced by As and Si. A multivariate statistical approach was utilized to establish the relationship between tissue As and Si concentrations and selected biochemical aspects of the stress response mechanisms to identify a set of relevant stress response descriptors. This resulted in the recognition of strong cultivar and temporal effects on metabolic and biochemical stress parameters following the treatments. In this paper the metabolic changes in H2O2 content, lipid peroxidation, lycopene and carotenoids content, ascorbate and GSH redox state, total phenolics, ABTS and DPPH radicals inhibition were in favor of an oxidative stress. The significance of some of these parameters as reliable arsenic exposition biomarkers is discussed in the context of the limited knowledge on the As-induced stress response mechanisms at the level of the ripening fruit which presents a distinctive molecular background dissimilar from roots and shoots.