Boron Toxicity Research Articles

Rational design of reverse osmosis membranes for boron removal: A counter-intuitive relationship between boron rejection and pore size

Owing to the toxicity of excess boron, developing reverse osmosis membranes that are capable of effectively removing boric acid, a boron specie commonly exists in seawater, is critical to advance water purification technology. To date, design principles of reverse osmosis membranes for boron removal have not yet been systematically explored. Using nanoporous graphene as a model system and by employing state-of-the-art molecular simulation techniques, this study discovers the critical role of the adsorptive competition of boric acid against water in the nanopores of membranes in their design. Specifically, the preferential adsorption of water onto the pore rims can be exploited to impede the permeation of boric acid, facilitating the size-exclusion effect for much improved boron rejection. Moreover, a well-balanced adsorptive competition is desired; water adsorption should not be too strong so that efficient water permeation can still be preserved. This results in membranes that are not only highly permeable but also capable of effectively removing boric acid. Detailed investigations on energetic, dynamics, and spatial distribution of water and boric acid as well as their free energy landscapes are also conducted for better understandings. Moreover, bilayer nanoporous graphene membranes with a heterogeneous design are identified to effectively block both boric acid and salt with a decent water permeation. Overall, the outcomes achieved herein can fundamentally guide the rational design of reverse osmosis membranes for more efficient and effective boron removal.

MITIGATION EFFECTS OF WATER-SOLUBLE CHITOSAN ON BORON TOXICITY IN PEPPER PLANTS

Excess boron in soil is often found in dry agricultural areas and is one of the factors limiting crop yields. Polysaccharide-based biostimulants can mitigate the harmful effects of environmental stresses on plants. I performed this study under controlled greenhouse conditions to understand the response of pepper plants under boron stress to treatment with water-soluble chitosan (WSC). I watered plants with 50 or 100 mg/l WSC and 1.5 mM boric acid solution. As a result of WSC application at both concentrations, plants were taller and had more leaves and greater leaf length, width, relative chlorophyll content, and fresh aboveground weight compared with the control. Plants exposed to boron stress had fewer leaves, a lower relative chlorophyll content, and leaf blade damage indicative of boron toxicity. At the same time, boron-exposed plants showed a marked increase in the leaf nitrogen, phosphorus, potassium, and boron contents. Applying WSC at both concentrations modulated boron stress in plants by improving plant growth; reducing boron accumulation in leaves; and increasing the available nitrate nitrogen, phosphorus, and potassium contents in the substrate.

The Critical Levels of Boron for Germination and Seedling Growth of Melon

This study was conducted to determine the effects of boron levels on germination and seedling growth of melon cultivars with different fruit characteristics under laboratory conditions. The seeds of three melon cultivars (Hasanbey 1, Kırkağaç 589, and Toros Sarıbal) were germinated at different boron levels (0, 20, 40, 60, 80, and 100 mg L-1) constituted by sodium borate (Na2B8O13.4H2O). Germination percentage, mean germination time, germination index, seedling growth parameters, and seedling dry matter were investigated. The optimum and toxicity levels of boron were calculated by regression analysis. Germination percentage, mean germination time, and germination index were not affected by increasing boron levels. A boron dose of 20 mg L-1 promoted root length, shoot length, and seedling fresh weight of melon; however, seedling growth of melon cultivars was inhibited at higher boron levels than 40 mg L-1. Seedling dry weight and dry matter significantly enhanced when the boron levels were increased. Root length was more sensitive to boron than shoot length. Melon cultivars showed different responses to boron levels and the highest seedling growth parameters were obtained from Kırkağaç 589. The optimum boron level for shoot growth was calculated as 12.8 mg L-1, while the inhibitory level of boron for root growth was 65.4 mg L-1. The toxicity of boron on the germination performance was not detected and higher levels than 20 mg L-1 inhibited seedling growth of melon.

Role of ABA in the adaptive response of Arabidopsis plants to long-term boron toxicity treatment

Boron (B) toxicity causes impairments in several plant metabolic and physiological processes. Under conditions of excessive B availability, this micronutrient is passively transported through the transpiration stream and accumulates in leaves, causing the development of necrotic regions in leaf tips. Some plants have developed adaptive mechanisms to minimize the toxic effects of excessive B accumulation in their tissues. Thus, for instance, in Arabidopsis it has been described an ABA-dependent decrease in the transpiration rate that would restrict B accumulation in aerial plant tissues in response to short-term B toxicity, this effect being mediated by AtNCED3 (which encodes a key enzyme for ABA biosynthesis). The present work aimed to study the possible involvement of ABA in the adjustment of plant water balance and B homeostasis during the adaptive response of Arabidopsis to prolonged B toxicity. For this purpose, Arabidopsis wild-type and the ABA-deficient nced3-2 mutant plants were subjected to B toxicity for 7 days. We show that ABA-dependent stomatal closure is determinant for the adjustment of plant water relations under conditions of prolonged B toxicity. Results suggest that, in addition to the AtNCED3 gene, the AtNCED5 gene could also be involved in this ABA-dependent stomatal closure. Finally, our results also indicate the possible role of endogenous root ABA content in the mechanism of active efflux of B via BOR4 (efflux-type B transporter) from the root to the external environment under excess B conditions.

The Fungal Root Endophyte Serendipita indica (Piriformospora indica) Enhances Bread and Durum Wheat Performance under Boron Toxicity at Both Vegetative and Generative Stages of Development through Mechanisms Unrelated to Mineral Homeostasis.

While the importance of beneficial soil microorganisms for soil health and crop performance has been receiving ever-increasing attention, Serendipita indica has been widely studied as a fungal root endophyte with significant potential for increasing the stress tolerance of host plants. Boron (B) toxicity as an adverse soil condition is particularly prevalent in arid and semi-arid regions and threatens crop production. Studies on S. indica-wheat symbiosis are limited, and effects of S. indica on crops have never been reported in the context of B toxicity. Here, two pot experiments were conducted under greenhouse conditions to investigate the effects of S. indica on the growth and yield parameters of bread (Triticum aestivum) and durum wheat (Triticum durum) grown at different levels of B toxicity in native vs. sterilized soil, and parameters related to root colonization, membrane damage, oxidative stress, chlorophyll, and mineral nutrition were measured to elucidate the physiological mechanisms of damage and benefit. Boron toxicity decreased early vegetative growth and grain yield, but it did not affect the straw dry weight of mature plants, whereas S. indica significantly enhanced the vegetative growth, straw dry weight, and the grain number of both wheat species. Membrane damage as demonstrated by increased lipid peroxidation and relative electrolyte leakage was caused by B toxicity and alleviated by S. indica. The benefits provided by S. indica could not be attributed to any significant changes in tissue concentrations of B or other minerals such as phosphorus. Soil sterilization generally improved plant performance but it did not consistently strengthen or weaken the effects of S. indica. The presented results suggest that S. indica may be used as an effective microbial inoculant to enhance wheat growth under adverse soil conditions such as B toxicity through mechanisms that are possibly unrelated to mineral homeostasis.

Carbon allocation of Spirodela polyrhiza under boron toxicity.

Pectic polysaccharides containing apiose, xylose, and uronic acids are excellent candidates for boron fixation. Duckweeds are the fastest-growing angiosperms that can absorb diverse metals and contaminants from water and have high pectin content in their cell walls. Therefore, these plants can be considered excellent boron (B) accumulators. This work aimed to investigate the relationship between B assimilation capacity with apiose content in the cell wall of Spirodela polyrhiza subjected to different boric acid concentrations. Plants were grown for 7 and 10 days in ½ Schenck-Hildebrandt media supplemented with 0 to 56 mg B.L-1, the non-structural and structural carbohydrates, and related genes were evaluated. The results showed that B altered the morphology and carbohydrate composition of this species during plant development. The optimum B concentration (1.8 mg B.L-1) led to the highest relative growth and biomass accumulation, reduced starch, and high pectin and apiose contents, together with increased expression of UDP-apiose/UDP-xylose synthase (AXS) and 1,4-α-galacturonosyltransferase (GAUT). The toxic state (28 and 56 mg B.L-1) increased the hexose contents in the cell wall with a concomitant reduction of pectins, apiose, and growth. The pectin content of S. polyrhiza was strongly associated with its growth capacity and regulation of B content within the cells, which have AXS as an important regulator. These findings suggest that duckweeds are suitable for B remediation, and their biomass can be used for bioenergy production.

Leaf Proteomic Analysis in Seedlings of Two Maize Landraces with Different Tolerance to Boron Toxicity.

Boron (B) toxicity is an important stressor that negatively affects maize yield and the quality of the produce. The excessive B content in agricultural lands is a growing problem due to the increase in arid and semi-arid areas because of climate change. Recently, two Peruvian maize landraces, Sama and Pachía, were physiologically characterized based on their tolerance to B toxicity, the former being more tolerant to B excess than Pachía. However, many aspects regarding the molecular mechanisms of these two maize landraces against B toxicity are still unknown. In this study, a leaf proteomic analysis of Sama and Pachía was performed. Out of a total of 2793 proteins identified, only 303 proteins were differentially accumulated. Functional analysis indicated that many of these proteins are involved in transcription and translation processes, amino acid metabolism, photosynthesis, carbohydrate metabolism, protein degradation, and protein stabilization and folding. Compared to Sama, Pachía had a higher number of differentially expressed proteins related to protein degradation, and transcription and translation processes under B toxicity conditions, which might reflect the greater protein damage caused by B toxicity in Pachía. Our results suggest that the higher tolerance to B toxicity of Sama can be attributed to more stable photosynthesis, which can prevent damage caused by stromal over-reduction under this stress condition.

Botanical and physiological parameters response of black bean (Phaseolus vulgaris L.) cultivars under increasing boron concentrations

Argentina is one of the five leading exporters of common bean (Phaseolus vulgaris L.) worldwide. Although common bean has been characterized as sensitive to boron toxicity, its production is often subjected to high boron concentrations. The aim of this study was to provide detailed information on the impact of increasing boron concentrations (0.5–8.0 mg L−1) on germination, growth, and root anatomy of two black bean cultivars (Leales 24 and Uirapurú) frequently produced in Argentina. Standard germination assays and pot greenhouse experiments were conducted. Radicles obtained in germination assays were used to make cross sections, which were analyzed under the microscope to identify anatomical alterations. Increasing boron concentrations had no effect on germination variables. In contrast, most of the growth variables analyzed (height, leaf area, fresh and dry weight, and water content) showed a steady decrease for boron concentrations above 1.0 mg L−1. Tissue boron concentrations showed an increase when boron concentrations increased. At the microscopic level, there seemed to be a decreasing trend in xylem vessel diameter. Our results suggest that boron concentrations above 1.0 and 2.0 mg L−1 may cause considerable growth and yield decreases in Uirapurú and Leales 24, respectively, thus affecting Argentinian bean production. Additionally, our results suggest that Leales 24 is moderately sensitive to boron toxicity and is best adapted for production in areas with higher boron concentrations. These findings highlight the importance of evaluating boron concentrations in soils and irrigation water in agricultural areas, and selecting cultivars best adapted to local conditions as tools for obtaining higher yields.

Potential application of melatonin in reducing boron toxicity in rice seedlings through improved growth, cell wall composition, proline, and defense mechanisms

Melatonin (MT) has been demonstrated to provide defense against both biotic and abiotic stressors. Boron toxicity (BT) can significantly limit the growth and production of plants. However, few studies have been conducted on whether MT is effective in attenuating B toxicity in different plants. In order to evaluate the efficacy of exogenous MT treatment in reducing the negative impact of BT on rice seedlings, this study examined the influence of MT on growth, antioxidant capacity, cell wall composition, and proline metabolism in rice seedlings under hydroponics. Four treatments were established: MT (50 μM), MT + BT (50 μM MT + 800 μM B), BT (800 μM), and CK (control) in a completely randomized design. The results indicate that BT had a significant detrimental effect on the shoot length, root length, and root and shoot fresh weights of rice seedlings by 11.96%, 27.77%, 25.69%, and 18.67%, respectively as compared to the control treatment. However, exogenous MT application increased these parameters and reduced B accumulation in aboveground parts (14.05%) of the plant. Exogenous MT also increased the endogenous melatonin content and antioxidant enzyme activities (64.45%, 71.61%, 237.64%, and 55.42% increase in superoxide dismutase, ascorbate peroxidase, and peroxidase activities, respectively), while decreasing reactive oxygen species levels and oxidized forms of glutathione and ascorbic acid. Additionally, MT enhanced the biosynthesis of proline by decreasing proline dehydrogenase (ProDH) and increasing the GSH (glutathione) and ASA (ascorbic acid) contents. Exogenous MT also increased cell wall components that can increase B adsorption to the cell wall. Overall, these findings suggest that MT application can be a potential solution for strengthening the stress tolerance of rice seedlings, particularly under conditions of B toxicity. In regions where soil contains high levels of boron, the use of MT could enhance rice crop yields and quality.

Effects of EDTA on boron toxicity to the green algae Chlamydomonas reinhardtii, Chlorella sorokiniana, and Chlorella vulgaris

This study investigated whether the toxicity of boron to the green algal species Chlamydomonas reinhardtii, Chlorella sorokiniana, and Chlorella vulgaris was affected by the presence of ethylenediaminetetraacetic acid (EDTA). As EDTA exists widely in aquatic ecosystems, its effects must be considered when assessing metal toxicity. C. vulgaris was found to be the most insensitive among the three algae, as there was little change in the toxicity of boron for this species in the presence of EDTA when compared with that for the other species. In contrast, C. reinhardtii and C. sorokiniana were both highly sensitive to boron in the presence of EDTA. Based on Visual MINTEQ modeling results, we found that EDTA combined with micronutrients. This chelation reduced their availability for uptake by the algae; consequently, the algae were highly sensitive to boron. These results will be useful for future assessments of risk and management of boron in aquatic ecosystems.

Boron bio-mining by high boron-tolerant native microalgae in Turkey and boron toxicity in the aquatic environment.

Boron (B) is one of the most important trace elements. Turkey has the largest B reserves in the world with 3 billion tons of B. Therefore, the toxicity of B is more important in Turkey. In this study, effective B removal was provided by different types of microalgae and then B recovery in culture media by bio-mining was detected. The water of Lake Mogan in Gölbaşı/Ankara/Turkey was used as the microalgae culture medium as a cost-reducing factor. The effects of light, temperature, NaNO3 and K2HPO4 stresses on B removal were determined. The highest B removal was 17.19% at 25 μmol/m2s light intensity and 25 °C for Phormidium animale in Lake Mogan culture medium. Boron removal of Scenedesmus sp. was 36.42% at 25 μmol/m2s light intensity, at 25 °C, at 1.5 g/L NaNO3 and 40 mg/L K2HPO4 concentrations in BG11 medium on the 15th day. The chl (a + b) concentration of Scenedesmus sp. was 1.63 μg/mL at 75 μmol/m2s light intensity and the chl (a) concentration of P. animale was 2.01 μg/mL at 25 μmol/m2s light intensity. Considering all parameters, Scenedesmus sp. and P. animale are recommended as effective biomaterials for the B removal process.

Physiological and Nutritional Responses of Ungrafted Merlot and Cabernet Sauvignon Vines or Grafted to 101-14 Mgt and 1103P Rootstocks Exposed to an Excess of Boron

The aim of this study is to analyze the effect of excess boron (B) on the nutrient uptake, growth, and physiological performance of grapevines. Merlot and Cabernet Franc grapevines, either own-rooted or grafted onto 1103P and 101-14 Mgt rootstocks, were exposed in a hydroponic pot experiment to 0.5 mM boron for sixty days. Twenty-five days following the beginning of B treatment, the first symptoms of boron toxicity appeared, including leaf edge and margin yellowing, subsequent necrosis, and cupping of leaf blades. At harvest, sixty days after the start of the experiment, B concentration of the treated vines increased in all parts of the vine in the following order: Leaves > Roots > Trunks > Shoots. Leaf Boron concentration in treated vines ranged from 980.67 to 1064.37 mg kg−1 d.w. Boron excess significantly reduced the concentrations of all macro and micronutrients studied in this experiment. The total leaf chlorophyll (Chl) concentration decreased from 35.46 to 44.45%, thirty and sixty days, respectively, from the beginning of the boron treatments. In addition, an excess amount of boron resulted in a dramatic decrease in net CO2 assimilation rate, stem water potential, and PSII maximum quantum yield, irrespective of vine type (own-rooted or grafted). At the end of the experimental period, the total leaf phenolic content increased by 71.73% in Merlot and by 71.16% in Cabernet Franc due to Boron stress. The tressed vines grafted onto 1103P showed increased shoot and root dry weights, leaf chlorophyll content, CO2 assimilation rates, and Fv/Fm ratio compared to vines grafted onto 101-14 Mgt. It was found that rootstocks play an important role in B toxicity. The results showed that the leaf accumulation of boron was delayed to a greater extent by 1103P rootstock compared to 101-14 Mgt, resulting in the earlier appearance of leaf toxicity symptoms in vines grafted onto 101-14 Mgt rootstock compared to 1103P.

Mitigation effects of Rhizophagus intraradices and Micrococcus yunnanensis on boron toxicity in maize (Zea may L.) plant

A greenhouse pot experiment was conducted to investigate the effect of arbuscular mycorrhiza fungus and plant growth promoting rhizobacterium on maize (Zea may L.) growth as well as nutrient concentrations under different levels of boron (B). Five levels of B (0, 10, 20, 40 and 60 mg B kg−1 as boric acid) and four levels of microbial inoculants (non-inoculation, Rhizophagus intraradices, Micrococcus yunnanensis, and co-inoculation) were used. Shoot and root dry weights significantly decreased as B levels increased. An increase in plant growth was observed at the levels of 10 and 20 mg B kg−1 due to microbial inoculation especially mycorrhization. Shoot and root dry weights positively correlated with shoot phosphorus concentration and root colonization. At the level of 40 mg B kg−1, root colonization significantly decreased. Shoot iron, copper, sodium and zinc concentrations significantly increased under excessive B concentrations. Totally, B application at low quantity improved plant growth while at higher rates it seemed toxic. Nonetheless, the inoculation of bacterium and arbuscular mycorrhiza had a more alleviative effect when the plant was exposed to excess B.

Glutathione and Proline Attenuates Injury Induced by Boron Toxicity in Wheat

Given the increasing importance of boron (B) toxicity, the present study investigates the roles of glutathione (20 mM, GSH) and proline (20 mM) in the improvement of wheat (Triticum aestivum cv. Altındane) resistance to B toxicity (10 mM B). The plants were raised in hydroponic culture with control, B toxicity, B+glutathione, B+proline, glutathione and proline. B+glutathione and B+proline resisted the detrimental influences of B toxicity on the root and shoot lengths, the total chlorophyll, and phenolic contents. B toxicity increased superoxide radicals (O2.-), hydrogen peroxide (H2O2), lipid peroxidation (MDA), and proline contents while B+glutathione and B+proline applications diminished the mentioned parameters with the exception of the proline content. Individual B toxicity and combined B+glutathione and B+proline applications increased generally total ascorbic acid and glutathione levels in the wheat while the B+proline application decreased GSH content. The B toxicity decreased superoxide dismutase, catalase and guaiacol peroxidase activities in compared with control with the exception of the ascorbate peroxidase activity. Exogenous glutathione and proline augmented all enzyme activities in the wheat exposed to B toxicity. As a result, it can be suggested that glutathione and proline mitigates B toxicity; by preventing oxidative damage in the membrane, by increasing enzymatic and non-enzymatic antioxidant and by decreasing O2.-, H2O2, and MDA contents. Glutathione is generally more effective than proline in mitigating the above detrimental effects of B toxicity. The datum submitted in the current work are significant and the first to indicate that effects of exogenous glutathione and proline in improving a culture plant strength to B toxicity.

Ethylenediamine-graphene oxide impregnated thin film nanocomposite membrane for the enhanced boron separation from seawater

The separation of toxic boron from seawater using nanofiltration (NF) membrane technology is challenging due to the neutral charge associated with boric acid at seawater pH. In this study, the ethylenediamine functionalized Graphene oxide (EDA-GO) derivative is utilized as a nanofiller to coat the active top layer of the NF membrane over the polyethersulfone ultrafiltration support. The coating involved a self-assembly reaction of hydrolyzed trimesic acid (TMA) molecules facilitated by a triethylamine base. The unique hypothesis for coating enabled the –NH2 of EDA-GO to interact with the –COOH of TMA via hydrogen bonding interactions. The rejection shown by the M-0.05 membrane with 0.05wt% loading of EDA-GO towards MgSO4, Na2SO4, and NaCl was >98%, >97%, and 63%, respectively. The same membrane produced water flux in the range of 35-37 L/m2h with the modest significance of the salts on the membrane flux. The M-0.05 membrane showed significantly higher rejection towards boron (>47%) with a flux of 16.7 L/m2h for the beachwell seawater feed owing to the repulsive interaction between the borate ions and -NH2 and -OH groups. The rejection and flux offered by the M-0.05 membrane towards seawater's monovalent and divalent constituents were much higher than the commercial NF-90 and NF-270.

Insight into the Boron Toxicity Stress-Responsive Genes in Boron-Tolerant Triticum dicoccum Shoots Using RNA Sequencing

Wheat production losses due to boron (B) toxicity can be reduced by breeding and growing modern wheat cultivars with a greater tolerance to high B. However, breeding of tolerant genotypes is possible by identifying B-tolerant wheat genetic resources and understanding their underlying molecular mechanism. Triticum dicoccum, despite being one of the oldest cultivated wheat species, mostly remained neglected and has been less explored for its potential towards abiotic stresses. In this study, for the first time, we report a B-toxicity-tolerant T. dicoccum genotype, PI94655, and its transcriptomic response towards high-B treatment (10 mM B) using RNA sequencing and RT-qPCR. More than 450 genes were significantly differentially expressed in the shoots of PI94655 under high B. A total 3237 novel genes and 12,206 novel transcripts were determined in the study. AP2-EREBP, MYB, and C3H were the families with the highest percentages of differentially expressed transcription factors (TFs) under B toxicity. Interestingly, KEGG pathway photosynthesis–antenna proteins showed the most significant enrichment. The obtained results suggested potential candidate genes that can be focused on to improve wheat tolerance to high B in future breeding programs. These genes can be functionally characterized to elucidate their role in providing tolerance to high B.

Effect of thermal characteristics on the chemical quality of real-brine treatment through hydrophilic fiber-based low-grade heat-powered humidification-dehumidification process

Considering the increasing demand for desalination plants and their byproduct brine, this study investigated a humidification-dehumidification (HDH) system for treating membrane distillation-generated real high-salinity brine using low-grade heat (45–70 ℃) to explore its feasibility for sustainable energy-efficient minimal liquid discharge. A novel super-hydrophilic fabric was adopted for accelerated humidification, and its impact on brine droplet miscarriage characteristics was evaluated. The influence of the operating fluid thermal properties (cycle 1: air preheating; cycle 2: air and brine dual-fluid preheating; and cycle 3: air post-heating after humidification) on the brine treatment efficiency, energy consumption, and chemical quality of freshwater produced was analyzed in detail to establish their characteristic nexus. It was identified that, during humidification, increasing the brine temperature (up to 55 ℃) influenced its ionic mobility, thereby promoting efficient separation of the salts/minerals and contributing to achieving better freshwater quality. Furthermore, although cycle 3 exhibited improved system thermal efficiency (gained output ratio equal to 1.77), its non-preheated air contributed to a negative effect of the reduced humidity ratio (∼17 g/kg), leading to a lower freshwater productivity of 67% than that of cycle 2 (29 g/kg and 70%). The present study also illustrates a novel effect of evaporative deposition occurring due to air-water interaction on the fabric humidifier surface, with an exploration of its effect on reducing freshwater chemical quality. The freshwater generated from optimum thermal cycle 2 exhibited reduced pH (by ∼63%), sodium (99.9%), chloride (99.9%), toxic boron (99.7%), and other chemical contaminants, thereby satisfying the major international water reuse standards.

Boron toxicity induces sulfate transporters at transcriptional level in Arabidopsis thaliana

Plants activate glutathione (GSH)-dependent detoxification pathways at biochemical and molecular levels under boron (B) toxicity. Sulfate uptake and transport are necessary for GSH biosynthesis in plants. Therefore, the transcriptional regulation of some sulfate transporters was determined in this study to clarify the importance of these transporters in leaf and root tissues of Arabidopsis thaliana under toxic B conditions. The expression level of SULTR1;3 was dramatically increased in leaf and root tissues under moderate and severe toxic B conditions, suggesting source-to-sink sulfate translocation under B toxicity. Stable expression levels of SULTR2;1, SULTR2;2, and low SULTR3;5 expression might restrict the sulfate movement into the xylem in leaves. SULTR3;1, SULTR3;2, SULTR3;3, SULTR3;4, SULTR4;1 and SULTR4;2 were induced in root tissues under toxic B conditions, indicating an induction of root-to-shoot sulfate translocation. These results showed that B toxicity might disrupt the homogeneous distribution of sulfate and sulfur-containing compounds in both tissues of A. thaliana. Moreover, we performed in silico analysis of microarray experiments to determine the common differentially expressed genes (DEGs) under B toxicity and sulfur deficiency. Gene ontology, hierarchical clustering, and coexpression network analyses of these DEGs demonstrated the requirement of sulfate transporters under B toxicity. A set of genes involved in sulfur metabolism coexpress with sulfate transporters under B toxicity. To the best of our knowledge, this is the first report focusing on the molecular regulation of sulfate transporters in Arabidopsis thaliana under B toxicity.

Boron toxicity tolerance in barley may be related to intrinsically higher levels of reactive oxygen species in the shoots

There is considerable intra-and interspecific variation in boron (B) toxicity tolerance in crop plants. In this study, we aimed to investigate the mechanisms involved in tolerance to excess B in barley (Hordeum vulgare) in the early stages of plant development. To do this, B-sensitive (B?lb?l-89) and B-tolerant (Tarm-92) barley cultivars were grown hydroponically under control and B stress conditions (10 mM H3BO3) for 4 or 7 days. The hydrogen peroxide (H2O2), malondialdehyde (MDA), total phenolic, total flavonoid, anthocyanin, proline, and total sugar contents, as well as DPPH radical scavenging capacity, were then determined for both cultivars. Our results showed that B treatment led to significant increases in the B concentration of the barley cultivars for both exposure times. However, there were no drastic differences in the B concentration of the roots and shoots between the sensitive and tolerant cultivars. While the dry root weight of B?lb?l-89 was reduced after 7 days of B stress (p < 0.05), such a decrease was not observed in Tarm-92. The H2O2, MDA, proline, total sugar, and anthocyanin contents of both cultivars increased considerably in response to excess B during at least one treatment period (p < 0.05). The H2O2 content of Tarm-92 under control and B stress conditions was significantly greater than that of B?lb?l-89, but there was no difference in the MDA content and radical scavenging capacity between the two cultivars. Finally, a 35% increase was found in the total flavonoid content of the Tarm-92 seedlings exposed to B stress for 4 days. In conclusion, the findings of this study suggest that tolerance to B toxicity in barley seedlings may be related to their capacity to tolerate higher levels of reactive oxygen species.

An Experimental Study to Evaluate the Action of Zincum Phosphoricum of Various Potencies against Boron Induced Toxicity in Solanum lycopersicum through Hydrophonic System

Agro homoeopathy is a boon now a days, where homoeopathy is acting like a fertilizer, insecticide and add more nutritive value. It is helping the public with organic veggies. This study is regarding boron toxicity in Solanum lycopersicum, where with hydrophonic system boron toxicity is induced and been treated with Zincum Phosphoricum of different potencies. After the study few potencies of Zincum Phosphoricum showed a drastic influence in the total yield of the plant.