Essential Element For Plants Research Articles

Solubility Relationship of Metals in Acid Soils of Kumaon Himalaya Region of India

ABSTRACT This study evaluated metal availability under acidic soil conditions and identified the solid phases that govern their solubility using Baker soil test. Free metal ion activity (Mn+) expressed as negative logarithm value (pMn+ = -log10 Mn+) of iron (pFe3+), manganese (pMn2+), copper (pCu2+), zinc (pZn2+), nickel (pNi2+), cadmium (pCd2+), and lead (pPb2+) ranged from 17.5 to 21.3, 5.2 to 8.4, 12.2 to 15.3, 9.3 to 11.9, 11.5 to 14.8, 11.8 to 15.1, and 10.9 to 13.4, respectively. The activities of Fe, Cu, Zn, Ni, Cd, and Pb in the soil solution are likely to be buffered by exchange reactions rather than precipitation-dissolution reactions. However, bixybite and manganite oxides are likely to govern the free Mn2+ activity in the soils. Based on intensity and quantity parameters, the soils were found to have sufficient supply power for plant essential elements (i.e. Fe, Mn, Cu, Zn, and Ni) except in the coarse-textured soils of Kosi. Nevertheless, the toxicity of iron in Someshwar and cadmium in Dhaili soils is expected under the prevailing soil conditions. The generated information on the solubility vis-à-vis availability of metals under acidic soil conditions will contribute to enlarge a field of research which is crucial for land management and deserves more attention, particularly in the fragile mountainous ecosystem.

Transport, functions, and interaction of calcium and manganese in plant organellar compartments.

Calcium (Ca2+) and manganese (Mn2+) are essential elements for plants and have similar ionic radii and binding coordination. They are assigned specific functions within organelles, but share many transport mechanisms to cross organellar membranes. Despite their points of interaction, those elements are usually investigated and reviewed separately. This review takes them out of this isolation. It highlights our current mechanistic understanding and points to open questions of their functions, their transport, and their interplay in the endoplasmic reticulum (ER), vesicular compartments (Golgi apparatus, trans-Golgi network, pre-vacuolar compartment), vacuoles, chloroplasts, mitochondria, and peroxisomes. Complex processes demanding these cations, such as Mn2+-dependent glycosylation or systemic Ca2+ signaling, are covered in some detail if they have not been reviewed recently or if recent findings add to current models. The function of Ca2+ as signaling agent released from organelles into the cytosol and within the organelles themselves is a recurrent theme of this review, again keeping the interference by Mn2+ in mind. The involvement of organellar channels [e.g. glutamate receptor-likes (GLR), cyclic nucleotide-gated channels (CNGC), mitochondrial conductivity units (MCU), and two-pore channel1 (TPC1)], transporters (e.g. natural resistance-associated macrophage proteins (NRAMP), Ca2+ exchangers (CAX), metal tolerance proteins (MTP), and bivalent cation transporters (BICAT)], and pumps [autoinhibited Ca2+-ATPases (ACA) and ER Ca2+-ATPases (ECA)] in the import and export of organellar Ca2+ and Mn2+ is scrutinized, whereby current controversial issues are pointed out. Mechanisms in animals and yeast are taken into account where they may provide a blueprint for processes in plants, in particular, with respect to tunable molecular mechanisms of Ca2+ versus Mn2+ selectivity.

Phytohormone content in brown macroalgae Sargassum from Lombok coast, Indonesia

Exessive use of inorganic fertilizers in rice production systems, causes various negative effects in the environemnt, such as reducing soil fertility and increases pollution, which disturbs agricultural sustainability. Understanding raw materials for developing organic fertilizers which are cheap and adaptive to our environment, is an important study recently. Many researchers reported that brown algae could increase growth and yield of several species of plants. This due to brown algae extract contain plant growth hormone and essential elements to stimulate growth and production of plants. This article report growth and yield of rice plants suplied with mixtured extract of brown algae. Several species of brown algae were collected in coastal beach of Lombok. The seaweeds were cutted into small peaces, extracted with boiled water for 30 minute and filtered using filter whatman no.1 to get solid and liquid extract. Mixtured solid extracts were added in soil media. On the other hand, the mixtured liquid extracts were sprayed to rice plants during vegetative growth. The results shown that mixtured solid extracts increased growth and yield of rice plants. However, mixtured liquid extract did not stimulate growth and yield of rice plants. This suggests that brown algae is a potential raw material for development of organic fertilizers, which are adaptive to environment to support sustainable agriculture.

Spatial Distribution of Soil Nutrients in Farmland in a Hilly Region of the Pearl River Delta in China Based on Geostatistics and the Inverse Distance Weighting Method

Soil nutrients are essential factors that reflect farmland quality. Nitrogen, phosphorus, and potassium are essential elements for plants, while silicon is considered a “quasi-essential” element. This study investigated the spatial distribution of plant nutrients in soil in a hilly region of the Pearl River Delta in China. A total of 201 soil samples were collected from farmland topsoil (0–20 cm) for the analysis of total nitrogen (TN), available phosphorus (AP), available potassium (AK), and available silicon (ASi). The coefficients of variation ranged from 47.88% to 76.91%. The NSRs of TN, AP, AK, and ASi were 0.15, 0. 07, 0.12, and 0.13, respectively. The NSRs varied from 0.02 to 0.20. All variables exhibited weak spatial dependence (R2 < 0.5), except for TN (R2 = 0.701). After comparing the prediction accuracy of the different methods, we used the inverse distance weighting method to analyze the spatial distribution of plant nutrients in soil. The uniform spatial distribution of AK, TN overall showed a trend of increasing from northeast to southwest, and the overall spatial distribution of AP and ASi showed that the northeast was higher than the southwest. This study provides support for the delimitation of basic farmland protection areas, the formulation of land use spatial planning, and the formulation of accurate farmland protection policies.

Establishing critical limits for nickel in soil and plant for predicting the response of spinach (spinacia oleracea)

Nickel (Ni) is an essential element for plants and research reports are available indicating its beneficial effects on growth of higher plants as well. Though abundant information exists on Ni toxicity in soil and plant system but not much is available on its critical level of deficiency (CLD) in soils and plants. A pot experiment was conducted in net-house of the micronutrient research project, Anand Agricultural University, Anand, Gujarat. For assessing the critical limit in soil, three bulk soils viz., low (<0.5 mg Ni kg−1), medium (0.5 to 1.0 mg Ni kg−1) and high (>1.0 mg Ni kg−1) were collected from different locations of Anand district. Six levels of Ni, i.e. Ni0, Ni2, Ni4, Ni6, Ni8 and Ni10 (0, 2.0, 4.0, 6.0, 8.0 and 10.0 mg Ni kg−1 soil) were applied in all 20 soils (10 low, 6 medium and 4 high in Ni content in soil). The experiment was conducted in factorial completely randomized design with three replications. The critical limit of Ni in soil was determined by Bray's per cent yield plotted against soil available Ni using the scattered diagram in graphical as well as statistical method. Wide variation in dry matter produce was observed across the soils. The concentration of Ni in spinach plant increased with increasing the level of Ni in soil. The CLD of the 0.005 M DTPA-CaCl2 extractable Ni in soil and plant was worked out as 0.46 and 2.27 mg kg−1, respectively with statistical method. Whereas, in graphical method it was reported as 0.50 and 2.20 mg kg−1, respectively in spinach crops.

Jian Feng Ma.

Jian Feng Ma.

The copper economy response is partially conserved in rice (Oryza sativa L.)

Copper (Cu) is an essential element for plants, especially in photosynthesis, as it is required for plastocyanin function in electron transfer reactions at thylakoid membranes. In Arabidopsis thaliana, Cu deficiency leads to the Cu economy response, in which plants prioritize Cu usage by plastocyanin in detriment of non-essential cupric proteins. In rice (Oryza sativa), however, this response has not been characterized. Rice OsHMA5 is a Cu xylem-loading transporter involved in Cu translocation from roots to shoots, as suggested by the analysis of oshma5 mutant plants. Aiming to understand how rice plants respond to Cu deficiency and how decreased Cu translocation to shoots can affect this response, we characterized the physiological and molecular responses of WT and oshma5 plants under control and Cu deficiency treatments. We found evidence that shoots of oshma5 plants are more prone to Cu deficiency compared to shoots of WT plants, as demonstrated by decreased chlorophyll and Cu concentrations, and electron transport rate. Gene expression analysis revealed that Cu high-affinity transporters OsCOPT1 and OsCOPT5, along with a set of miRNAs and three Cu/Zn superoxide dismutases are responsive to Cu deficiency in both WT and oshma5 plants, suggesting their involvement in the Cu economy response. However, Fe superoxide dismutase was not up-regulated in rice, indicating a difference compared to the A. thaliana Cu economy model. Therefore, we provide evidence for a partially conserved Cu economy response in rice, in comparison to A. thaliana.

Earthworm and arbuscular mycorrhiza interactions: Strategies to motivate antioxidant responses and improve soil functionality.

Earthworms and arbuscular mycorrhizal fungi (AMF) act synergistically in the rhizosphere and may increase host plant tolerance to Cd. However, mechanisms by which earthworm-AMF-plant partnerships counteract Cd phytotoxicity are unknown. Thus, we evaluated individual and interactive effects of these soil organisms on photosynthesis, antioxidant capacity, and essential nutrient uptake by Solanum nigrum, as well as on soil quality following Cd exposure (0-120mgkg-1). Decreases in biomass and photosynthetic activity, as well as nutrient imbalances were observed in Cd-stressed plants; however, the addition of AMF and earthworms reversed these effects. Cd exposure increased superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities, whereas inoculation with Rhizophagus intraradices decreased those. Soil enzymatic activity decreased by 15-60% with increasing Cd concentrations. However, Cd-mediated toxicity was partially reversed by soil organisms. Earthworms and AMF ameliorated soil quality based on soil enzyme activity. At 120mgkg-1 Cd, the urease, catalase, and acid phosphatase activities were 1.6-, 1.4-, and 1.2-fold higher, respectively, in soils co-incubated with earthworms and AMF than in uninoculated soil. Cd inhibited shoot Fe and Ca phytoaccumulation, whereas AMF and earthworms normalized the status of essential elements in plants. Cd detoxification by earthworm-AMF-S.nigrum symbiosis was manifested by increases in plant biomass accumulation (22-117%), chlorophyll content (17-63%), antioxidant levels (SOD 10-18%, POD 9-25%, total polyphenols 17-22%, flavonoids 15-29%, and glutathione 7-61%). It also ameliorated the photosynthetic capacity, and macro- and micronutrient statuses of plants; markedly reduced the levels of malondialdehyde (20-27%), superoxide anion (29-36%), and hydrogen peroxide (19-30%); and upregulated the transcription level of FeSOD. Thus, the combined action of earthworms and AMF feasibly enhances metal tolerance of hyperaccumulating plants and improves the quality of polluted soil.

Effect of Solid and Liquid Extracts of Lombok Sargassum cristafolium on Growth and Yield of Rice Plants (Oryza sativa L.)

An exessive use of inorganic fertilizers in agriculture cultivation system causes many disadventages, such as increase cost production, reduce farmer’s income and soil fertility, and harm our environment. Therefore, it is needed to find out raw materials for development of organic biostimulant and biofertilizer inducing essential element absorption, growth and yield of plants, which are adaptive to our environment as well. Previous researchres reported that seaweed contained plant growth hormones and essential elements in liquid and solid extracts respectively. This article reports effect of solid and liquid extracts of Sargassum cristafolium on growth and yield of rice plants. The extracts were extracted according to modified procedure.. Solid extract (350 gr) of Sargassum cristafolium was mixed with soil (6650 gr) to become 7 kg soil media. Moreover, liquid extract (10%) of Sargassum cristafolium was sprayed to rice plants once a week during vegetative growth. The results shown that addition of 350 gr of solid extract to soil media increased growth (plant high, tiller number, shoot dry weight and root dry weight) and yield (penicle number and grain weight per plants) significantly compared with those of plants which were not supplied with solid extract. However, spraying liquid extract of Sargassum cristafolium did not affet significantly growth and yield of rice plants, even small change happen in growth and yield parameters of the rice plants supplied with solid extract. This indicates that solid extract is a potential source for development of biofertilizer which is adaptive to our environment to support sustainable agriculture system.

Characterization of Nutrient Disorders and Impacts on Chlorophyll and Anthocyanin Concentration of Brassica rapa var. Chinensis

Essential plant nutrients are needed at crop-specific concentrations to obtain optimal growth and yield. Foliar tissue analysis is the standard method for assessing nutrient levels in plants. Symptoms of nutrient deficiency or toxicity occur when the foliar tissue values become too low or high. Diagnostic nutrient deficiency criteria for Brassica rapa var. Chinensis (bok choy) is lacking in the current literature. In this study, green (‘Black Summer’) and purple (‘Red Pac’) bok choy plants were grown in silica sand culture, with control plants receiving a complete modified Hoagland’s all-nitrate solution, and nutrient-deficient plants induced by using a complete nutrient formula withholding a single nutrient. Tissue samples were collected at the first sign of visual disorder symptoms and analyzed for dry weight and nutrient concentrations of all plant essential elements. Six weeks into the experiment, the newest matured leaves were sampled for chlorophyll a, b, and total carotenoids concentrations for both cultivars, and total anthocyanin concentration in ‘Red Pac’. Compared to control plants, the dry weight of ‘Black Summer’ green bok choy was significantly lower for nitrogen (N), phosphorus (P), calcium (Ca), or boron (B) deficiency treatments, and nutrient concentrations were lower for all variables except iron (Fe) deficiency. Dry weight was less in ‘Red Pac’ plants grown without N, potassium (K), Ca, B, or molybdenum (Mo), and nutrient concentrations were lower for all except Mo-deficiency compared to controls. Total chlorophyll and total carotenoid concentrations were lower in leaves from N−, Fe-, and manganese- (Mn) deficient plants of both cultivars. Leaf anthocyanin concentration was lower only for K-, Ca-, and B-deficiencies in ‘Red Pac’. Our results indicate that visual symptoms of nutrient deficiency are well correlated with nutrient disorders. In contrast, changes in dry weight, chlorophyll, and anthocyanin did not show consistent changes across nutrient disorders.

PH-dependent transcriptional profile changes in iron-deficient Arabidopsis roots

BackgroundIron is an essential element for plants and abundantly present in most mineral soils. The mobility of iron is, however, dependent on the redox potential and hydrogen activity (pH) of the soil, factors that may limit its availability to plants in particular at alkaline pHs. Iron deficiency triggers pronounced changes in the transcriptional profile of plants, inducing processes that aid in the acquisition, uptake, and translocation of iron. How ambient pH impact the transcriptional iron deficiency response has not yet been elucidated in detail.ResultsHere, we provide an RNA-seq data set that catalogs global gene expression changes of iron-deficient plants grown at either optimal (5.5) or high (7.0) pH. A suite of 857 genes changed significantly and more than twofold in expression; only 54 genes of this suite were also differentially expressed between iron-deficient and iron-sufficient plants grown at pH 5.5. Among the high pH-responsive genes, 186 were earlier shown to be responsive to short-term transfer to low pH, 91 genes of this subset were anti-directionally regulated by high and low pH. The latter subset contained genes involved in cell wall organization, auxin homeostasis, and potential hubs of yet undefined signaling circuits. Growing iron-deficient plants at high pH also modulated the transcriptional iron deficiency response observed at pH 5.5 by compromising the enzymatic reduction of ferric chelates and favoring the production of iron-mobilizing coumarins.ConclusionsIt is concluded that ambient pH is an important determinant of global gene expression which tunes iron acquisition to the prevailing edaphic conditions.

Agronomic Biofortification of Stevia rebaudiana with Zinc Oxide (ZnO) Phytonanoparticles and Antioxidant Compounds

Agronomic biofortification is a process used to increase the concentration of essential elements in plants through fertilization and thus improve their nutritional quality. Increasing the content of Zn+2 in Stevia rebaudiana plants would imply adding value to the crop. The use of ZnO phytonanoparticles, in addition to increasing the content of Zn+2, can also generate an inductor effect that promotes the synthesis of metabolites of commercial interest. This study reports the effect of fertilization with ZnO phytonanoparticles on morphometric parameters of S. rebaudiana plants and the content of Zn+2, stevioside, rebaudioside A, total phenols, flavonoids and the antiradical activity of leaf extracts. Biofortification was carried out in a hydroponic culture using peat moss/agrolite as a support under a completely random experimental design. The green ZnO nanoparticles were added via root at different concentrations. The physiological and morphometric parameters of the plant were not affected with respect to the control by the use of phytonanoparticles. The biofortification of S. rebaudiana with ZnO phytonanoparticles at a concentration of 75 mg/L enhanced zinc content up to 406.8% with respect to the control. The total phenols (60.5%) and flavonoids (87.8%) were also increased without having a negative effect on plant growth. The biosynthetic pathway of steviol glycosides was not affected.

Ionic Selenium and Nanoselenium as Biofortifiers and Stimulators of Plant Metabolism

Selenium (Se) is an essential element in mammals; however, there is frequently an insufficient intake due to several factors. Different techniques have been used to deal with this problem, such as plant biofortification with Se in its ionic forms and, more recently, at the nanoscale. Additionally, despite the fact that Se is not considered an essential element in plants, it has been shown to stimulate (through still unknown mechanisms) plant metabolism, causing an increase in the synthesis of molecules with reducing power, including enzymes such as glutathione peroxidase, catalase and ascorbate peroxidase as well as non-enzymatic antioxidants such as phenolic compounds, glucosinolates, vitamins and chlorophylls. A positive correlation has also been shown with other essential elements, achieving an increase in tolerance to environmental adversities. This article describes the advances made in the field of the biofortification of horticultural crops with ionic Se and nanoselenium (nSe) from 2009 to 2019. The aspects covered include various concentrations used, the findings made regarding the impact these chemical forms have on plant metabolism, and indications of its participation in the synthesis of primary and secondary metabolites that increase stress tolerance.

Silicon supplementation improves the nutritional and sensory characteristics of lentil seeds obtained from drought-stressed plants.

Lentil is an important nutritionally rich pulse crop in the world. Despite having a prominent role in human health and nutrition, it is very unfortunate that global lentil production is adversely limited by drought stress, causing a huge decline in yield and productivity. Drought stress can also affect the nutritional profile of seeds. Silicon (Si) is an essential element for plants and a general component of the human diet found mainly in plant-based foods. This study investigated the effects of Si on nutritional and sensory properties of seeds obtained from lentil plants grown in an Si-supplied drought-stressed environment. Significant enhancements in the concentration of nutrients (protein, carbohydrate, dietary fibre, Si) and antioxidants (ascorbate, phenol, flavonoids, total antioxidants) were found in seeds. Significant reductions in antinutrients (trypsin inhibitor, phytic acid, tannin) were also recorded. A novel sensory analysis was implemented in this study to evaluate the unconscious and conscious responses of consumers. Biometrics were integrated with a traditional sensory questionnaire to gather consumers responses. Significant positive correlations (R = 0.6-1) were observed between sensory responses and nutritional properties of seeds. Seeds from Si-treated drought-stressed plants showed higher acceptability scores among consumers. The results demonstrated that Si supplementation can improve the nutritional and sensory properties of seeds. This study offers an innovative approach in sensory analysis coupled with biometrics to accurately assess a consumer's preference towards tested samples. In the future, the results of this study will help in making a predictive model for sensory traits and nutritional components in seeds using machine-learning modelling techniques. © 2020 Society of Chemical Industry.

&lt;p&gt;Protective role of antioxidative enzymes and antioxidants against iron-induced oxidative stress in the cyanobacterium &lt;em&gt;Anabaena sphaerica&lt;/em&gt; isolated from iron rich paddy field of Chhattisgarh, India&lt;/p&gt;

Iron, as an essential element for plants and microorganisms, plays a significant role in photosynthesis, photopigment synthesis, nitrogen fixation, nucleic acid synthesis, etc. However, in iron rich environments, it causes stress by affecting various physiological activities including ROS generation and detoxification machineries. Here, we investigated the protective role of antioxidative enzymes and antioxidants against iron-induced oxidative stress in the cyanobacteria, Anabaena sphaerica from the iron rich regions of Chhattisgarh. We evaluated various morpho-physiological modifications at different concentrations of iron (0, 20, 50, 75 and 100 µM FeCl 3 ). Microscopic and physiological characterization showed highest order of structural deformities, reactive oxygen species (ROS) generation and lipid peroxidation at 100 µM FeCl 3 but growth was reduced only by 28%. Possibly, maximum superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities along with highest level of antioxidants (carotenoid, proline, cysteine and non protein thiol) played a major role in protecting the growth. As compared to 20 µM FeCl 3 treated cells of A. sphaerica , almost equal growth and no structural alterations at 50 and 75 µM FeCl 3 may be correlated with minimum ROS, electrolyte leakage and malondialdehyde (MDA) content along with an activation of efficient ROS detoxification machinery i.e. enhanced level of antioxidative enzymes and antioxidants. Thus, the inherited property of A. sphaerica to grow at iron enriched condition make it more efficient microbe for improvement of the nitrogen status in the soil.

Transcriptomic analysis at organ and time scale reveals gene regulatory networks controlling the sulfate starvation response of Solanum lycopersicum

BackgroundSulfur is a major component of biological molecules and thus an essential element for plants. Deficiency of sulfate, the main source of sulfur in soils, negatively influences plant growth and crop yield. The effect of sulfate deficiency on plants has been well characterized at the physiological, transcriptomic and metabolomic levels in Arabidopsis thaliana and a limited number of crop plants. However, we still lack a thorough understanding of the molecular mechanisms and regulatory networks underlying sulfate deficiency in most plants. In this work we analyzed the impact of sulfate starvation on the transcriptome of tomato plants to identify regulatory networks and key transcriptional regulators at a temporal and organ scale.ResultsSulfate starvation reduces the growth of roots and leaves which is accompanied by major changes in the organ transcriptome, with the response being temporally earlier in roots than leaves. Comparative analysis showed that a major part of the Arabidopsis and tomato transcriptomic response to sulfate starvation is conserved between these plants and allowed for the identification of processes specifically regulated in tomato at the transcript level, including the control of internal phosphate levels. Integrative gene network analysis uncovered key transcription factors controlling the temporal expression of genes involved in sulfate assimilation, as well as cell cycle, cell division and photosynthesis during sulfate starvation in tomato roots and leaves. Interestingly, one of these transcription factors presents a high identity with SULFUR LIMITATION1, a central component of the sulfate starvation response in Arabidopsis.ConclusionsTogether, our results provide the first comprehensive catalog of sulfate-responsive genes in tomato, as well as novel regulatory targets for future functional analyses in tomato and other crops.

Silicon Supply Improves Leaf Gas Exchange, Antioxidant Defense System and Growth in Saccharum officinarum Responsive to Water Limitation

Silicon (Si) is not categorized as a biologically essential element for plants, yet a great number of scientific reports have shown its significant effects in various crop plants and environmental variables. Plant Si plays biologically active role in plant life cycle, and the significant impact depends on its bioaccumulation in plant tissues or parts. In particular, it has been investigated for its involvement in limited irrigation management. Therefore, this experiment was conducted to examine the effect of Si application in eco-physiological, enzymatic and non-enzymatic activities of sugarcane plants against water stress. Four irrigation levels, i.e., normal (100–95% of soil moisture), 80–75, 55–50, and 35–30% of soil moisture were treated for the sugarcane cultivar GT 42 plants supplied with 0, 100, 200, 300, 400 and 500 mg Si L−1 and exposed for 60 days after Si application. Under stress, reduction in plant length (~26–67%), leaf area-expansion (~7–51%), relative water content (~18–57%), leaf greenness (~12–35%), photosynthetic pigments (~12–67%), physiological responses such as photosynthesis (22–63%), stomatal conductance (~25–61%), and transpiration rate (~32–63%), and biomass production were observed in the plants without Si application. The drought condition also inhibited the activities of antioxidant enzymes like catalase (~10–52%), peroxidase (ca. 4–35), superoxide dismutase (10–44%) and enhanced proline (~73–410%), and malondialdehyde content (ca. 15–158%), respectively. However, addition of Si ameliorated drought induced damage in sugarcane plants. The findings suggest that the active involvement of Si in sugarcane responsive to water stress ranges from plant performance and physiological processes, to antioxidant defense systems.

Alleviation mechanisms of metal(loid) stress in plants by silicon: a review.

Silicon (Si), although not considered as an essential element for plants in general, can ameliorate the phytotoxicity induced by excess metal(loid)s whether non-essential (e.g. Cd, Pb, Cr, Al, As, and Sb) or essential (e.g. Cu, Ni, and Zn). The Si-enhanced resistance allowing plants to cope with this type of abiotic stress has been developed at multiple levels in plants. Restriction of root uptake and immobilization of metal(loid)s in the rhizosphere by Si is probably one of the first defence mechanism. Further, retention of elements in the root apoplasm might enhance the resistance and vigour of plants. At the cellular level, the formation of insoluble complexes between Si and metal(loid)s and their storage within cell walls help plants to decrease available element concentration and restrict symplasmic uptake. Moreover, Si influences the oxidative status of plants by modifying the activity of various antioxidants, improves membrane stability, and acts on gene expression, although its exact role in these processes is still not well understood. This review focuses on all currently known plant-based mechanisms related to Si supply and involved in amelioration of stress caused by excess metal(loid)s.

Quantifying beryllium concentrations in plant shoots from forest ecosystems using cation-exchange chromatography and quadrupole ICP-MS.

Beryllium (Be) is known to be one of the most toxic elements but at the same time exerts a stimulating effect on plant growth. Despite this contradiction, little is known about the Be metabolism in living organisms, partially because of the low amounts present and because the analysis of Be in plants by ICP-MS remains challenging. The challenges arise from the complex organic matrix, the low abundance of Be relative to the other plant essential elements, and the matrix effects resulting thereof in the plasma. To address these challenges, we developed and evaluated a new method for Be concentration analysis in plant material. Key is the quantitative separation of Be from the other matrix elements by cation-exchange chromatography. The new method was verified by processing seven reference materials representing different plant matrices yielding a long-term reproducibility of 16% (RSD). Applying the method, Be concentrations in tree, shrub, bush, and grass samples grown in non-polluted ecosystems from four temperate forests and a tropical rainforest were measured. The Be concentrations in different plant organs range from 0.01 to 63ng/g that suggest a natural baseline for Be concentrations of 52ng/g (95 percentile of non-woody tissue) that may serve as bioindicator for Be pollution in the environment. Comparison of Be concentrations in plants with the soil's biologically available fraction revealed that Be is discriminated from uptake into shoots and thus can be considered as non-essential.

Nickel Occurrence in a Livestock Food Chain (Northwestern Italy)

Nickel (Ni) is an essential element in plants and animals, but elevated levels can exert toxicity in living beings, as recently highlighted by the European Food Safety Authority opinion. However, literature regarding the presence of nickel in the environment is scarce. In 2016, the EU Commission Recommendation n°1110 recommended monitoring the presence of Ni in feed in order to set maximum levels or to adopt other risk management measures to ensure a high level of animal health protection and consequently of human health. A total of 200 samples of feedingstuffs, drinking water, and milk were collected from dairy cow farms in Piedmont, and analyzed for Ni concentration by Z-ETA-AAS. Results showed the presence of nickel in feedingstuffs in a range from 0.20 to 16 mg/kg, while Ni concentrations in water and milk were close to or below the limit of quantitation. There was no carry-over from feed to milk in this food chain. Nickel concentrations were not of concern for animal health despite being in the upper range of those observed in vegetables from Europe.