Traceability of Croatian extra virgin olive oils to the provenance soils by multielement and carbon isotope composition and chemometrics.

A capacity to determine the provenance of high-value food products is of high scientific and economic interest. With the aim to develop a tool for geographical traceability of Croatian extra virgin olive oils (EVOO), multielement composition and 13C/12C isotope ratio in EVOO as well as the geochemistry of the associated soils were analysed in samples collected from three regions along the Croatian Adriatic coast. Soil geochemistry was shown to influence the transfer and elemental composition of EVOO. The most discriminating variables to distinguish EVOO from different regions were S, Mo, Rb, Mg, Pb, Mn, Sn, K, V and δ13C. The predictive models achieved high sensitivity and specificity, especially when carbon isotope composition was added. The results suggest that interregional geographical traceability of Croatian EVOO is possible based on matching their multielement composition with that of the soils in the provenance area.

Copper accumulation in five weed species commonly found in the understory vegetation of Mediterranean vineyards.

Copper (Cu) concentration in agricultural soils often exceeds toxicological limits due to application of Cu-based fungicides. The potential of weeds for their use as functional cover plants in vineyard management and phytoremediation practices is little explored. We identified five weed species widely present in vineyards and assessed their Cu accumulation from eleven Mediterranean vineyards (soil Cu: 60-327 µg g-1) and two adjacent control sites (soil Cu: 15-30 µg g-1). Soils and plants were characterized by their physico-chemical properties and nutrient content. We applied multivariate techniques to analyze relationships between soil properties and leaf nutrient composition. Copper tolerance and accumulation traits were further tested in hydroponics using a series of CuSO4 concentrations (0.1-16 µM). Under field conditions, the highest Cu concentration in both roots and leaves were found in Lolium perenne (221 and 461 µg g-1, respectively), followed by Plantago lanceolata, Rumex obtusifolius and Taraxacum officinale (>100 µg g-1 Cu in leaves). Only one species, Trifolium repens, did not accumulate remarkable Cu concentrations. Overall, and as revealed by the multivariate analyses, leaf Cu concentration was driven by soil Cu content, soil texture, organic matter, nitrogen, and Cu uptake into roots. However, functional regression analysis and controlled experiments suggested that Cu might be additionally absorbed from the deposits on the leaf surface related to the Cu-fungicide treatments and soil dust. Our study highlights the importance of intra-specific variability in Cu accumulation among weed species in Cu-contaminated agricultural soils. Further validation of these findings under controlled conditions could provide essential insights for optimizing management and remediation strategies.

Comprehensive insights in thallium ecophysiology in the hyperaccumulator Biscutella laevigata.

Biscutella laevigata is the strongest known thallium (Tl) hyperaccumulator plant species. However, little is known about the ecophysiological processes leading to root uptake and translocation of Tl in this species, and the interactions between Tl and its chemical analogue potassium (K). Biscutella laevigata was subjected to hydroponics experimentation in which it was exposed to Tl and K, and it was investigated in a rhizobox experiment. Laboratory-based micro-X-ray fluorescence spectroscopy (µ-XRF) was used to reveal the Tl distribution in the roots and leaves, while synchrotron-based µ-XRF was utilised to reveal elemental distribution in the seed. The results show that in the seed Tl was mainly localised in the endosperm and cotyledons. In mature plants, Tl was highest in the intermediate leaves (16,100 µg g-1), while it was one order of magnitude lower in the stem and roots. Potassium did not inhibit or enhance Tl uptake in B.laevigata. At the organ level, Tl was localised in the blade and margins of the leaves. Roots foraged for Tl and cycled Tl across roots growing in the control soils. Biscutella laevigata has ostensibly evolved specialised mechanisms to tolerate high Tl concentrations in its shoots. The lack of interactions and competition between Tl and K suggests that it is unlikely that Tl is taken up via K channels, but high affinity Tl transporters remain to be identified in this species. Thallium is not only highly toxic but also a valuable metal and Tl phytoextraction using B. laevigata should be explored.

Independent variation in copper tolerance and copper accumulation among crop species and varieties.

Copper (Cu) locally contaminates soils and might negatively affect growth and yield of crops. A better understanding of plant copper tolerance and accumulation is needed in order to breed more Cu-tolerant or Cu-efficient crops. Cu tolerance was evaluated in different varieties of seven species (Brassica carinata, B. juncea, B. napus, Cynara cardunculus, Helianthus annuus, Nicotiana tabacum and Raphanus sativus) exposed to a series of CuSO4 concentrations (0.1-8 µM CuSO4) in the nutrient solution. Plants were further exposed to 0.1 µM CuSO4 and to their variety-specific concentrations that reduced root growth to 50% of the maximum rate (EC50). Among all the varieties of all the species the EC50 varied from 0.7 up to 3.1 µM Cu. B. carinata was significantly more Cu-sensitive than the other species, which were not significantly different among each other, and B. carinata and H. annuus accommodated significant intra-specific, inter-varietal variation. There were significant differences between species in Cu uptake efficiency and nutrient status. When under EC50 exposure, all the Brassicaceae, except B. carinata, maintained low Cu concentrations in shoots, whereas the other species and B. carinata exhibited significantly increased shoot Cu concentrations, compared to the control. There was no apparent relationship between Cu tolerance and Cu accumulation in roots and shoots, suggesting that the observed variation in tolerance, both between and within species, is not explained by differential exclusion capacity. Discriminant analysis and treatment comparisons suggest possible contribution of lignin, saturated fatty acids, manganese (Mn) and zinc (Zn) in tolerance to high Cu concentrations in shoot.

Manganese soil and foliar fertilization of olive plantlets: the effect on leaf mineral and phenolic content and root mycorrhizal colonization.

BACKGROUND: The present study aimed to examine the effect of foliar (Mn_fol) and soil Zeolite-Mn (Mn_ZA) application on leaf mineral, total phenolic and oleuropein content, and mycorrhizae colonization of self-rooted cv. Leccino plantlets grown on calcareous soil. RESULTS: The dissolution of zeolite was 97% when citric acid was applied at 0.05 mM dm-3 , suggesting that organic acids excreted by roots can dissolve modified zeolite (Mn_ZA), making Mn available for plant uptake. The leaf Mn concentration was the highest for Mn_fol treatment at 90 days after transplanting (DAT) (172 mg kg-1 ) and 150 DAT (70 mg kg-1 ) compared to other treatments. Mn_ZA soil application increased leaf Mn concentration at 150 DAT compared to control and NPK treatments. The oleuropein leaf content was highest for Mn_fol compared to other treatments at 90 DAT and lowest at 150 DAT. Arbuscular mycorrhizal colonization was higher for Mn_fol treatment at 150 DAT compared to all other treatments. CONCLUSION: Changes in the arbuscular colonization percentage and oleuropein content may be connected to stress conditions provoked by a high leaf Mn concentration in the Mn_fol treatment at 90 DAT. Mn_ZA application increased leaf Mn concentration at 150 DAT compared to control and NPK treatments. It can be assumed that the dominant mechanism in Mn uptake from modified zeolite is Mn_ZA dissolution through root exudates. © 2018 Society of Chemical Industry.

Cerium negatively impacts the nutritional status in rapeseed.

Cerium (Ce) has been reported to be both beneficial and harmful to plants. This contradiction deserves explanation in the light of increased anthropogenic release of Ce in the environment. Ce tolerance and accumulation were evaluated in hydroponically cultivated Brassica napus L. (rapeseed). Ce and other nutrient concentrations were measured with increasing Ce concentration in the nutrient solution. Moreover, Ce and calcium (Ca) accumulation were evaluated at different Ca and Ce concentrations in nutrient solution and a Michaelis-Menten type inhibition model considering Ce and Ca competition was tested. Plants were also sprayed with Ce solution in Ca-deficient media. Ce decreased the growth and root function, which affected shoot nutritional status. Calcium was the most severely inhibited nutrient in both roots and shoots. High Ca concentrations in the nutrient solution inhibited Ce accumulation in a non-competitive way. Moreover, phosphorus (P) precipitated Ce inside root cells. Ce spraying did not alleviate Ca deficiency symptoms and the results were critically compared to the available literature.

Effects of Cerium and Titanium Oxide Nanoparticles in Soil on the Nutrient Composition of Barley (Hordeum vulgare L.) Kernels.

The implications of metal nanoparticles (MeNPs) are still unknown for many food crops. The purpose of this study was to evaluate the effects of cerium oxide (nCeO2) and titanium oxide (nTiO2) nanoparticles in soil at 0, 500 and 1000 mg·kg(-1) on the nutritional parameters of barley (Hordeum vulgare L.) kernels. Mineral nutrients, amylose, ß-glucans, amino acid and crude protein (CP) concentrations were measured in kernels. Whole flour samples were analyzed by ICP-AES/MS, HPLC and Elemental CHNS Analyzer. Results showed that Ce and Ti accumulation under MeNPs treatments did not differ from the control treatment. However, nCeO2 and nTiO2 had an impact on composition and nutritional quality of barley kernels in contrasting ways. Both MeNPs left ß-glucans unaffected but reduced amylose content by approximately 21%. Most amino acids and CP increased. Among amino acids, lysine followed by proline saw the largest increase (51% and 37%, respectively). Potassium and S were both negatively impacted by MeNPs, while B was only affected by 500 mg nCeO2·kg(-1). On the contrary Zn and Mn concentrations were improved by 500 mg nTiO2·kg(-1), and Ca by both nTiO2 treatments. Generally, our findings demonstrated that kernels are negatively affected by nCeO2 while nTiO2 can potentially have beneficial effects. However, both MeNPs have the potential to negatively impact malt and feed production.

Changes in Physiological and Agronomical Parameters of Barley (Hordeum vulgare) Exposed to Cerium and Titanium Dioxide Nanoparticles.

The aims of our experiment were to evaluate the uptake and translocation of cerium and titanium oxide nanoparticles and to verify their effects on the growth cycle of barley (Hordeum vulgare L.). Barley plants were grown to physiological maturity in soil enriched with either 0, 500 or 1000 mg · kg(-1) cerium oxide nanoparticles (nCeO2) or titanium oxide nanoparticles (nTiO2) and their combination. The growth cycle of nCeO2 and nTiO2 treated plants was about 10 days longer than the controls. In nCeO2 treated plants the number of tillers, leaf area and the number of spikes per plant were reduced respectively by 35.5%, 28.3% and 30% (p ≤ 0.05). nTiO2 stimulated plant growth and compensated for the adverse effects of nCeO2. Concentrations of Ce and Ti in aboveground plant fractions were minute. The fate of nanomaterials within the plant tissues was different. Crystalline nTiO2 aggregates were detected within the leaf tissues of barley, whereas nCeO2 was not present in the form of nanoclusters.

Evidence of Phytotoxicity and Genotoxicity in Hordeum vulgare L. Exposed to CeO2 and TiO2 Nanoparticles.

Engineered nanoscale materials (ENMs) are considered emerging contaminants since they are perceived as a potential threat to the environment and the human health. The reactions of living organisms when exposed to metal nanoparticles (NPs) or NPs of different size are not well known. Very few studies on NPs-plant interactions have been published, so far. For this reason there is also great concern regarding the potential NPs impact to food safety. Early genotoxic and phytotoxic effects of cerium oxide NPs (nCeO2) and titanium dioxide NPs (nTiO2) were investigated in seedlings of Hordeum vulgare L. Caryopses were exposed to an aqueous dispersion of nCeO2 and nTiO2 at, respectively 0, 500, 1000, and 2000 mg l(-1) for 7 days. Genotoxicity was studied by Randomly Amplified Polymorphism DNA (RAPDs) and mitotic index on root tip cells. Differences between treated and control plants were observed in RAPD banding patterns as well as at the chromosomal level with a reduction of cell divisions. At cellular level we monitored the oxidative stress of treated plants in terms of reactive oxygen species (ROS) generation and ATP content. Again nCeO2 influenced clearly these two physiological parameters, while nTiO2 were ineffective. In particular, the dose 500 mg l(-1) showed the highest increase regarding both ROS generation and ATP content; the phenomenon were detectable, at different extent, both at root and shoot level. Total Ce and Ti concentration in seedlings was detected by ICP-OES. TEM EDSX microanalysis demonstrated the presence of aggregates of nCeO2 and nTiO2 within root cells of barley. nCeO2 induced modifications in the chromatin aggregation mode in the nuclei of both root and shoot cells.

Variation in Heavy Metal Accumulation and Genetic Diversity at a Regional Scale Among Metallicolous and Non-Metallicolous Populations of the Facultative Metallophyte Biscutella laevigata subsp. laevigata.

Biscutella laevigata is a facultative metallophyte, with populations on non-metalliferous and metalliferous soils. Some of its metallicolous populations have been shown to hyperaccumulate thallium or lead in nature. Only Tl hyperaccumulation has been experimentally confirmed. We aimed to compare the patterns of metal (hyper)accumulation and genetic diversity among populations of B. laevigata subsp. laevigata in NE Italy. None of the populations exhibited foliar hyperaccumulation of Cu, Zn, or Pb. The root-to-shoot accumulation rates for these metals were unchanged or decreased rather than enhanced in the metallicolous populations, in comparison with the non-metallicolous ones. Hyperaccumulation of Tl was confined to the population of the Cave del Predil mine. This population was genetically very distinct from the others, as demonstrated by AFLP-based cluster analysis. The two other mine populations did not surpass the threshold for Tl hyperaccumulation, but showed enhanced foliar Tl concentrations and root-to-shoot translocation rates, in comparison with the non-metallicolous populations. Genetic analysis suggested that adaptation to metalliferous soil must have been independently evolved in the metallicolous populations.

In vivo synthesis of nanomaterials in plants: location of silver nanoparticles and plant metabolism.

Metallic nanoparticles (MeNPs) can be formed in living plants by reduction of the metal ions absorbed as soluble salts. It is very likely that plant metabolism has an important role in MeNP biosynthesis. The in vivo formation of silver nanoparticles (AgNPs) was observed in Brassica juncea, Festuca rubra and Medicago sativa. Plants were grown in Hoagland's solution for 30 days and then exposed for 24 h to a solution of 1,000 ppm AgNO3. In the leaf extracts of control plants, the concentrations of glucose, fructose, ascorbic acid, citric acid and total polyphenols were determined. Total Ag content in plant fractions was determined by inductively coupled plasma atomic emission spectroscopy. Despite the short exposure time, the Ag uptake and translocation to plant leaves was very high, reaching 6,156 and 2,459 mg kg-1 in B. juncea and F. rubra, respectively. Ultrastructural analysis was performed by transmission electron microscopy (TEM), and AgNPs were detected by TEM X-ray microanalysis. TEM images of plant fractions showed the in vivo formation of AgNPs in the roots, stems and leaves of the plants. In the roots, AgNPs were present in the cortical parenchymal cells, on the cell wall of the xylem vessels and in regions corresponding to the pits. In leaf tissues, AgNPs of different sizes and shapes were located close to the cell wall, as well as in the cytoplasm and within chloroplasts. AgNPs were not observed in the phloem of the three plant species. This is the first report of AgNP synthesis in living plants of F. rubra. The contents of reducing sugars and antioxidant compounds, proposed as being involved in the biosynthesis of AgNPs, were quite different between the species, thus suggesting that it is unlikely that a single substance is responsible for this process. MSC 2010: 92 Biology and other natural sciences; 92Cxx Physiological, cellular and medical topics; 92C80 Plant biology.