| 1. |
- Awad-Allah, Eman F. A., et al.
(författare)
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Phosphorus protects against cadmium-induced phytotoxicity by stimulating plasma membrane H+-ATPase activity
- 2023
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Ingår i: Journal of plant nutrition. - 0190-4167 .- 1532-4087. ; 46:16, s. 3918-3932
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Tidskriftsartikel (refereegranskat)abstract
- Proper plant nutrition can be an effective strategy to alleviate the phytotoxicity and damaging effects of Cd stress on plants and to avoid its entry into the food chain. This study aimed to investigate effects of phosphorus concentrations, and pH levels in the nutrient solution on Cd uptake, growth, photosynthetic characters, total phytochelatins (PCs), and plasma membrane ATPase activity of sugar beet (Beta vulgaris L.) plants grown in sand culture. Two successive experimental studies were carried out under controlled conditions. In the first study, 10-day-old sugar beet seedlings were irrigated with a half-strength Hoagland and Arnon nutrient solution, adjusted to different pH (3.5, 5.0, 6.0, 7.0, or 8.0), and containing 0, 0.15, or 0.30 mg Cd L−1 as CdCl2. In the second study, 10-day-old sugar beet seedlings were irrigated with the same nutrient solution (pH 6), but combined with different phosphorus concentrations (0, 10, 25 and 50 µg P ml−1 as KH2PO4) and Cd levels (0, 0.15, and 0.30 mg Cd L−1 as CdCl2). The first study revealed that pH had a strong influence on Cd uptake by sugar beet roots. Cd stress significantly decreased sugar beet growth and Mg2+-ATPase activity, whereas it increased total phytochelatins (PCs). Second study indicated an antagonistic effect between P and Cd. Furthermore, phosphorus had the potential to stimulate Mg2+-ATPase activity and synthesis of photosynthetic pigments and to promote growth of sugar beet seedlings. Cadmium induced phytotoxicity in sugar beet seedlings can be alleviated by a proper pH and phosphorus nutrition.
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| 2. |
- Bergqvist, Claes, 1977-
(författare)
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Arsenic accumulation in plants for food and phytoremediation : Influence by external factors
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Arsenic (As) appears in the environment as various As species, which may vary in plant uptake and toxicity. Moreover, As exposure may vary between habitat due to availability and speciation, both of which are influenced by redox potential. To decrease As uptake, addition of silicate may be a tool.The aim of the study was to investigate how the external factors As availability, plant habitats, silicon and oxygen level, influenced the accumulation and speciation of As in plants for food and phytoremediation in a temperate region. The external factors were chosen due to their previously showed influence on As in plants.The risks with dietary As was investigated by plant As accumulation and speciation in carrot, lettuce and spinach grown in alum shale and glassworks soils, and by the influence of silicon on As accumulation in lettuce in hydroponics. Suitable plants for As phytoremediation was investigated by analysing plants from various habitats, and by the O2 influence on phytofiltration.The results showed that vegetables accumulated more As in soils with higher As extractability, and the As extractability in the rhizosphere was higher than in bulk soil. Also, the As concentration in lettuce was higher in hydroponics than in soil, but silicon reduced the accumulation of As in lettuce in hydroponics. Also, the more toxic inorganic As were the main As species detected in vegetables, compared with the less toxic organic As. For phytoremediation, the results showed a low As accumulation in emergent and terrestrial plants. Submerged plants had had a higher shoot As concentration. In general, the habitat had a major influence on the As accumulation in plants. The results also showed that the As accumulation properties in Elodea canadensis was reduced at higher O2.In conclusion, consumption of vegetables cultivated in As polluted soils can result in an elevated intake of inorganic As, and E. canadensis is a promising candidate for As phytofiltration in a temperate region.
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| 3. |
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| 4. |
- Cherian, Sam, et al.
(författare)
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Phytoremediation of Trace element Contaminated Environments and the Potential of Endophytic Bacteria for Improving this Process
- 2012
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Ingår i: Critical reviews in environmental science and technology. - : Informa UK Limited. - 1064-3389 .- 1547-6537. ; 42:21, s. 2215-2260
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Forskningsöversikt (refereegranskat)abstract
- Trace elements (heavy metals and metalloids) are among the most widespread contaminants that pose serious threat to all living organisms. Plant and microbial-assisted remediation holds great promise for in situ remediation of trace element contaminated environments. An extended knowledge of plant processes generally involved in the uptake, translocation, storage and detoxification of contaminants, and plant-microbe interactions were essential in developing improved technologies for environmental clean up. Currently, with the initiation of transgenic technologies, great strides have been made in trace element phytoremediation research. In this review, we provide an overview of the current knowledge of how plants cope with trace elements and discuss the development of transgenic plants with improved trace element remediation capabilities. In addition, this review also addresses the recent progress made towards understanding the plant-microbe interactions, especially of endophytic bacteria (natural and genetically engineered), and their contribution in improving the efficiency and versatility of trace element phytoremediation.
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| 5. |
- D'Onofrio, Cladio, et al.
(författare)
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Sodium induces simultaneous changes in cytosolic calcium and pH in salt-tolerant quince protoplasts
- 2009
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Ingår i: Journal of plant physiology (Print). - GmbH : Elsevier. - 0176-1617 .- 1618-1328. ; 166, s. 1755-1763
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Tidskriftsartikel (refereegranskat)abstract
- Previousexperimentswithsalt-resistantquinceBA29(Cydonia oblonga cv.Mill.) have shownthatthiscultivartakesupsodiumtransientlyintothecytosolofshoot protoplasts onlyintheabsenceofcalciumchloride,orat o1mMcalciumchloride. Addition ofNaClZ100mMtosingleprotoplastsfrom in vitro-cultivated quinceinthe presence of1.0mMcalciuminducedinstantchangesinthecytosolicconcentrations of calciumandprotons.Thesechangeswereinvestigatedbyuseoftetra [acetoxymethyl] estersofthefluorescentstilbenechromophoresFura2andbis- carboxyethyl-carboxyfluorescein (BCECF),respectively.ThecytosolicCa2+ dynamics in theprotoplastsweredependentontheconcentrationofNaCladded.Thechanges in calciumdifferedinamplitudeandfinalconcentrationandwerecorrelatedintime mainly withchangesinpH.Additionof100–400mMNaCltotheprotoplastscausedan oscillating increaseinthecytosoliclevelofcalcium,andthenadecrease.Addition of mannitol,ofequiosmolarconcentrationtoNaCl,didnotincreasethecytosolic calcium concentration.Moreover,therewasnoincreaseincytosoliccalciumwhen NaCl wasaddedinthepresenceofcalciumbindingethyleneglycol-bis(beta- aminoethylether)-N,N,N0,N0-tetra aceticacid(EGTA),orlantanorverapamil,two inhibitors ofplasmamembranecalciumchannels.Therefore,weconcludethat,in salt-resistant quince,sodiuminducesaninfluxofcalciumintothecytosolbyplasma membrane calciumchannels,andasimultaneousincreaseincytosolicpH.Because these changeswereobtainedinthepresenceof1mMcalciuminthemedium,they were notduetosodiumuptakeintothecytosol.
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| 6. |
- Greger, Maria, et al.
(författare)
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Silicate reduces cadmium uptake into cells of wheat
- 2016
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Ingår i: Environmental Pollution. - : Elsevier BV. - 0269-7491 .- 1873-6424. ; 211, s. 90-97
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Tidskriftsartikel (refereegranskat)abstract
- Cadmium (Cd) is a health threat all over the world and high Cd content in wheat causes high Cd intake. Silicon (Si) decreases cadmium content in wheat grains and shoot. This work investigates whether and how silicate (Si) influences cadmium (Cd) uptake at the cellular level in wheat. Wheat seedlings were grown in the presence or absence of Si with or without Cd. Cadmium, Si, and iron (Fe) accumulation in roots and shoots was analysed. Leaf protoplasts from plants grown without Cd were investigated for Cd uptake in the presence or absence of Si using the fluorescent dye, Leadmium Green AM. Roots and shoots of plants subjected to all four treatments were investigated regarding the expression of genes involved in the Cd uptake across the plasma membrane (i.e. LCT1) and efflux of Cd into apoplasm or vacuole from the cytosol (i.e. HMA2). In addition, phytochelatin (PC) content and PC gene (PCS1) expression were analysed. Expression of iron and metal transporter genes (IRT1 and NRAMP1) were also analysed. Results indicated that Si reduced Cd accumulation in plants, especially in shoot. Si reduced Cd transport into the cytoplasm when Si was added both directly during the uptake measurements and to the growth medium. Silicate downregulated LCT1 and HMA2 and upregulated PCS1. In addition, Si enhanced PC formation when Cd was present. The IRT1 gene, which was downregulated by Cd was upregulated by Si in root and shoot facilitating Fe transport in wheat. NRAMP1 was similarly expressed, though the effect was limited to roots. This work is the first to show how Si influences Cd uptake on the cellular level.
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| 7. |
- Gul, Mehreen, et al.
(författare)
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Potassium-induced decrease in cytosolic Na+ alleviates deleterious effects of salt stress on wheat (Triticum aestivum L.)
- 2019
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 21:5, s. 825-831
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Tidskriftsartikel (refereegranskat)abstract
- Accumulation of NaCl in soil causes osmotic stress in plants, and sodium (Na+) and chloride (Cl-) cause ion toxicity, but also reduce the potassium (K+) uptake by plant roots and stimulate the K+ efflux through the cell membrane. Thus, decreased K+/Na+ ratio in plant tissue lead us to hypothesise that elevated levels of K+ in nutrient medium enhance this ratio in plant tissue and cytosol to improve enzyme activation, osmoregulation and charge balance. In this study, wheat was cultivated at different concentrations of K+ (2.2, 4.4 or 8.8 mm) with or without salinity (1, 60 or 120 mm NaCl) and the effects on growth, root and shoot Na+ and K+ distribution and grain yield were determined. Also, the cytosolic Na+ concentration was investigated, as well as photosynthesis rate and water potential. Salinity reduced fresh weight of both shoots and roots and dry weight of roots. The grain yield was significantly reduced under Na+ stress and improved with elevated K+ fertilisation. Elevated K+ level during cultivation prevented the accumulation of Na+ into the cytosol of both shoot and root protoplasts. Wheat growth at vegetative stage was transiently reduced at the highest K+ concentration, perhaps due to plants' efforts to overcome a high solute concentration in the plant tissue, nevertheless grain yield was increased at both K+ levels. In conclusion, a moderately elevated K+ application to wheat seedlings reduces tissue as well as cytosolic Na+ concentration and enhances wheat growth and grain yield by mitigating the deleterious effects of Na+ toxicity.
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| 8. |
- Javed, Muhammad Tariq, 1983-, et al.
(författare)
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Cadmium induces cellular pH changes in Elodea canadensis and causes external basification
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Tidskriftsartikel (refereegranskat)abstract
- Earlier investigations showed that Elodea canadensis causes a basification of the surrounding medium in the presence of cadmium. This study was aimed to investigate the mechanism by which Cd causes this plant to increase the surrounding water pH. Cd-induced pH changes in cytosol, vacuole and apoplastic regions of E. canadensis were monitored by fluorescence microscopy and pH-specific fluorescent dyes. Since cytosolic Ca2+ and pH homeostasis are closely linked, the cytosolic calcium [Ca2+]cytwas also investigated after Cd treatment. Cd binding to the cell walls of E. canadensis was investigated after cultivation of plants at different fixed pH. We developed a new enzymatic method for the isolation of protoplasts from E. canadensis leaves. Cd exposure resulted in a subsequent increase in both cytosolic and vacuolar pH of leaf protoplasts and concomitant rise in the [Ca2+]cyt. Changes in [Ca2+]cyt and [pH]cyt followed the same dynamics upon Cd addition, but the changes in [pH]cyt seemed to be prior to the [Ca2+]cyt changes. Cd treatment decreased the apoplastic pH by 0.85 units and Cd contents of cell walls were enhanced at low pH. In conclusion, Cd exposure decreased the apoplastic pH of E. canadensis and resulted in Cd binding to the cell walls which may prevent Cd influx to the cytosol. The results suggest that the Cd-induced apoplastic acidification can be one of the mechanisms to increase the surrounding medium pH by E. canadensis shoots.
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| 9. |
- Javed, M. Tariq, et al.
(författare)
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Cadmium spiked soil modulates root organic acids exudation and ionic contents of two differentially Cd tolerant maize (Zea mays L.) cultivars
- 2017
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Ingår i: Ecotoxicology and Environmental Safety. - : Elsevier BV. - 0147-6513 .- 1090-2414. ; 141, s. 216-225
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Tidskriftsartikel (refereegranskat)abstract
- Our earlier work described that the roots of two maize cultivars, grown hydroponically, differentially responded to cadmium (Cd) stress by initiating changes in medium pH depending on their Cd tolerance. The current study investigated the root exudation, elemental contents and antioxidant behavior of the same maize cultivars (cv. 3062 (Cd-tolerant) and cv. 31P41 (Cd-sensitive)] under Cd stress. Plants were maintained in a rhizobox-like system carrying soil spiked with Cd concentrations of 0, 10, 20, 30, 40 and 50 mu mol/kg soil. The root and shoot Cd contents increased, while Mg, Ca and Fe contents mainly decreased at higher Cd levels, and preferentially in the sensitive cultivar. Interestingly, the K contents increased in roots of cv. 3062 at low Cd treatments. The Cd stress caused acidosis of the maize root exudates predominantly in cv. 3062. The concentration of various organic acids was significantly increased in the root exudates of cv. 3062 with applied Cd levels. This effect was diminished in cv. 31P41 at higher Cd levels. Cd exposure increased the relative membrane permeability, anthocyanin (only in cv. 3062), proline contents and the activities of peroxidases (POD) and superoxide dismutase (SOD). The only exception was the catalase activity, which was diminished in both cultivars. Root Cd contents were positively correlated with the secretion of acetic acid, oxalic acid, glutamic acid, citric acid, and succinic acid. The antioxidants like POD and SOD exhibited a positive correlation with the organic acids under Cd stress. It is likly that a high exudation of dicarboxylic organic acids improves nutrient uptake and activities of antioxidants, which enables the tolerant cultivar to acclimatize in Cd polluted environment.
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| 10. |
- Javed, M. Tariq, et al.
(författare)
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Cadmium uptake in Elodea canadensis leaves and its interference with extra- and intra-cellular pH
- 2014
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Ingår i: Plant Biology. - : Wiley. - 1435-8603 .- 1438-8677. ; 16:3, s. 615-621
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated cadmium (Cd) uptake in Elodea canadensis shoots under different photosynthetic conditions, and its effects on internal (cytosolic) and external pH. The plants were grown under photosynthetic (light) or non-photosynthetic (dark or in the presence of a photosynthetic inhibitor) conditions in the presence or absence of CdCl2 (0.5 mu m) in a medium with a starting pH of 5.0. The pH-sensitive dye BCECF-AM was used to monitor cytosolic pH changes in the leaves. Cadmium uptake in protoplasts and leaves was detected with a Cd-specific fluorescent dye, Leadmium Green AM, and with atomic absorption spectrophotometry. During cultivation for 3days without Cd, shoots of E.canadensis increased the pH of the surrounding water, irrespective of the photosynthetic conditions. This medium alkalisation was higher in the presence of CdCl2. Moreover, the presence of Cd also increased the cation exchange capacity of the shoots. The total Cd uptake by E.canadensis shoots was independent of photosynthetic conditions. Protoplasts from plants exposed to 0.5 mu m CdCl2 for 3days did not exhibit significant change in cytosolic [Cd2+] or pH. However, exposure to CdCl2 for 7days resulted in increased cytosolic [Cd2+] as well as pH. The results suggest that E.canadensis subjected to a low CdCl2 concentration initially sequesters Cd into the apoplasm, but under prolonged exposure, Cd is transported into the cytosol and subsequently alters cytosolic pH. In contrast, addition of 10-50 mu m CdCl2 directly to protoplasts resulted in immediate uptake of Cd into the cytosol.
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