| 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
-
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)
-
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)
-
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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| 11. |
- Javed, M. Tariq, et al.
(författare)
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Cellular proton dynamics in Elodea canadensis leaves induced by cadmium
- 2014
-
Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 77, s. 15-22
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Tidskriftsartikel (refereegranskat)abstract
- Our earlier investigations showed that Elodea canadensis shoots, grown in the presence of cadmium (Cd), caused basification of the surrounding medium. The present study was aimed to examine the proton dynamics of the apoplastic, cytosolic and vacuolar regions of E. canadensis leaves upon Cd exposure and to establish possible linkage between cellular pH changes and the medium basification. The changes in cytosolic calcium [Ca2+](cyt) was also investigated as the [Ca2+](cyt) and [pH](cyt) homeostasis are closely linked. The cellular H+ and Ca2+ concentrations were monitored by fluorescence microscopy and ion-specific fluorescent dyes. Cadmium concentration of leaf-cell walls was measured after plant cultivation at different fixed levels of starting pH. The protoplasts from E. canadensis leaves were isolated by use of a newly developed enzymatic method. Upon Cd addition, both cytosolic and vacuolar pH of leaf protoplasts increased with a concomitant rise in the cytosolic Ca2+ concentration. Time course studies revealed that changes in [Ca2+](cyt) and [PH](cyt) followed similar dynamics. Cadmium (0.5 mu M) exposure decreased the apoplastic pH by 0.85 units. The maximum cell wall bound Cd-contents were obtained in plants grown at low starting pH. It is concluded that Cd treatment causes apoplastic acidosis in E. canadensis leaves associated with enhanced Cd binding to the cell walls and, consequently, reduced Cd influx into the cytosol.
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| 12. |
- Javed, M. Tariq, 1983-, et al.
(författare)
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Changes in pH and organic acids in mucilage of Eriophorum angustifolium roots after exposure to elevated concentrations of toxic elements
- 2012
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 20:3, s. 1876-1880
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Tidskriftsartikel (refereegranskat)abstract
- The presence of Eriophorum angustifolium in mine tailings of pyrite maintains a neutral pH, despite weathering, thus lowering the release of toxic elements into acid mine drainage water. We investigated if the presence of slightly elevated levels of free toxic elements triggers the plant rhizosphere to change the pH towards neutral by increasing organic acid content. Plants were treated with a combination of As, Pb, Cu, Cd and Zn at different concentrations in nutrient medium and in soil in a rhizobox-like system for 48-120 hrs. The pH and organic acids were detected in the mucilage dissolved from root surface, reflecting the rhizosphere solution. Also the pH of root-cell apoplasm was investigated. Both apoplasmic and mucilage pH increased and the concentrations of organic acids enhanced in the mucilage with slightly elevated levels of toxic elements. When organic acid concentration was high, also the pH was high. Thus, efflux of organic acids from the roots of E. angustifolium may induce rhizosphere basification.
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| 13. |
- Javed, Muhammad Tariq, 1983-, et al.
(författare)
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Cytosolic uptake of cadmium causes an extra- and intra-cellular basification in Elodea canadensis
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The current study was aimed to investigate the pH changes by Elodea canadensis shoots under different photosynthetic conditions in the presence and absence of cadmium (Cd) and its influence on Cd uptake. Plants were grown under light, dark and in the presence of the photosynthetic inhibitor (3-(3,4-dichlorophenyl)-1,1-dimethylurea) with and without 0.5 µM Cd in the solution at a starting pH of 5.0. The Cd uptake into the cytosol of leaf protoplasts was investigated by using a Cd-specific fluorescent dye, LeadmiumTM Green AM. Cadmium and proton dynamics were monitored in leaf protoplasts after plant exposure to 0.5 µM CdCl2 for 3 and 7 d, respectively. The pH sensitive dye BCECF-AM was used to detect cytosolic pH changes. The shoots increased the surrounding water pH, which enhanced Cd uptake. Beside pH increase by photosynthetic activity, E. canadensis possessed additional mechanisms to raise the surrounding water pH in the presence of Cd. The cytosolic cadmium (Cd2+cyt) fluorescence of leaf protoplasts increased upon addition of CdCl2 to the external medium, reflecting (Cd2+cyt) uptake. Plant exposure to 0.5 µM CdCl2 for 3 d did not induce significant changes in (Cd2+cyt)and [pH]cyt. However, the (Cd2+cyt) and pHcyt were significantly increased after plant exposure to 0.5 µM CdCl2 for 7d. This suggests that E. canadensis initially sequester Cd in its apoplasmic region depending upon the presence of acidic polysaccharides in its cell wall and external medium basification. With time Cd translocates into the cytosol and subsequently causes its basification.
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| 14. |
- Javed, Muhammad Tariq, 1983-
(författare)
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Mechanisms behind pH changes by plant roots and shoots caused by elevated concentration of toxic elements
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Toxic elements are present in polluted water from mines, industrial outlets, storm water etc. Wetland plants take up toxic elements and increase the pH of the medium. In this thesis was investigated how the shoots of submerged plants and roots of emergent plants affected the pH of the surrounding water in the presence of free toxic ions. The aim was to clarify the mechanisms by which these plants change the surrounding water pH in the presence of toxic ions. The influence of Elodea canadensis shoots on the pH of the surrounding water was studied in the presence of cadmium (Cd) at low initial pH (4-5). The involvement of photosynthetic activity in the pH changes was investigated in the presence and absence of Cd. The cytosolic, vacuolar and apoplasmic pH changes as well as cytosolic Cd changes in E. canadensis were monitored. The influence of Eriophorum angustifolium roots on the pH of the surrounding water was investigated in the presence of a combination of Cd, copper, lead, zinc and arsenic at low initial pH (3.5). Eriophorum angustifolium root exudates were analyzed for organic acids. Elodea canadensis shoots increased the pH of the surrounding water, an effect more pronounced with increasing Cd levels and/or increasing plant biomass and increased plant Cd uptake. The pH increase in the presence of free Cd ions was not due to photosynthesis or proton uptake across the plasmalemma or tonoplast. Cadmium was initially sequestered in the apoplasm of E. canadensis and caused its acidosis. Eriophorum angustifolium roots increased the surrounding water pH and this effect was enhanced in the presence of arsenic and metals. This pH increase was found to depend partly on the release of oxalic acid, formic acid and succinic acid by the plants. In conclusion, E. canadensis shoots and E. angustifolium roots were found to increase the low initial pH of the surrounding water. The pH modulation by these species was enhanced by low levels of free toxic ions in the surrounding water.
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| 15. |
- Javed, Muhammad Tariq, 1983-, et al.
(författare)
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pH changes and organic acids exudation by Eriophorum angustifolium roots exposed to elevated concentration of toxic elements
-
Tidskriftsartikel (refereegranskat)abstract
- This study was aimed to investigate the influence of Eriophorum angustifolium roots on surrounding water pH in the presence of heavy metals and As, and the possible mechanism behind. We monitored the pH in the surrounding nutrient solution by E. angustifolium roots at a starting pH 3.5 and in the presence of a combination of As, Pb, Cu, Cd and Zn at different concentrations. The metal and As contents in the plant shoots and roots were analyzed as well as organic acids in the root exudates. Fluorescence microscopy and a pH-specific fluorescent dye were used to investigate the influence of different elements on apoplastic pH of E. angustifolium roots. The results showed that the roots have the ability to increase the rhizosphere pH even in the presence of different free metal ions and As. The plant root metal and As contents were significantly higher as compared with shoots. Metal and As treatment at higher concentrations significantly caused the apoplastic pH to increase in this species. Of the acids analyzed, the exudation of the oxalic, formic and succinic acids was significantly enhanced after metal and As exposure, as compared with control, giving the maximum concentration of these acids after 25 µM As, Cu, Zn, Pb and 2.5 µM Cd treatment. The roots of E. angustifolium respond to toxic ions by releasing organic acids, which transiently induce rhizosphere basification.
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| 16. |
- Kader, Abdul, 1969-, et al.
(författare)
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Cytosolic calcium and pH signaling in plants under salinity stress
- 2010
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Ingår i: Plant signaling and behavior. - Austin USA : Landes Bioscience. ; 5:3, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Calcium is one of the essential nutrients for growth and development of plants. It is an important component of various structures in cell wall and membranes. Besides some fundamental roles under normal condition, calcium functions as a major secondarymessenger molecule in plants under different developmental cues and various stress conditions including salinity stress. Also changes in cytosolic pH, pHcyt, either individually, or in coordination with changes in cytosolic Ca2+ concentration, [Ca2+]cyt, evoke a wide range of cellular functions in plants including signal transduction in plant-defense responses against stresses. It is believed that salinity stress, like other stresses, is perceived at cell membrane, either extra cellular or intracellular, which then triggers an intracellular-signaling cascade including the generation of secondary messenger molecules like Ca2+ and protons. The variety and complexity of Ca2+ and pH signaling result from the nature of the stresses as well as the tolerance level of the plant species against that specific stress. The nature of changes in [Ca2+]cyt concentration, in terms of amplitude, frequency and duration, is likely very important for decoding the specific downstream responses for salinity stress tolerance in planta. It has been observed that the signatures of [Ca2+]cyt and pH differ in various studies
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| 17. |
- Kader, Abdul M, et al.
(författare)
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Expressions of OsHKT1, OsHKT2, and OsVHA aredifferentially regulated under NaCl stress in salt-sensitiveand salt-tolerant rice (Oryza sativa L.) cultivars
- 2006
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Ingår i: Journal of Experimental Botany. - Oxford : Society for Experimental Biology. - 0022-0957 .- 1460-2431. ; 57:15, s. 4257-4268
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Tidskriftsartikel (refereegranskat)abstract
- Under NaCl-dominated salt stress, the key to plant survivalis maintaining a low cytosolic Na+ level or Na+/K+ratio. The OsHKT1, OsHKT2, and OsVHA transportergenes might play important roles in maintaining cytosolicNa+ homeostasis in rice (Oryza sativa L. indica cvsPokkali and BRRI Dhan29). Upon NaCl stress, theOsHKT1 transcript was significantly down-regulatedin salt-tolerant cv. Pokkali, but not in salt-sensitive cv.BRRI Dhan29. NaCl stress induced the expression ofOsHKT2 and OsVHA in both Pokkali and BRRI Dhan29.In cv. Pokkali, OsHKT2 and OsVHA transcripts wereinduced immediately after NaCl stress. However, in cv.BRRI Dhan29, the induction of OsHKT2 was quite lowand of OsVHA was low and delayed, compared with thatin cv. Pokkali. OsHKT2 and OsVHA induction mostlyoccurred in the phloem, in the transition from phloemto mesophyll cells, and in the mesophyll cells of theleaves. The vacuolar area in cv. Pokkali did not changeunder either short- (5–10 min) or long-term (24 h) saltstress, although it significantly increased 24 h afterthe stress in cv. BRRI Dhan29. When expressionalconstructs of VHA-c and VHA-a with YFP and CFP wereintroduced into isolated protoplasts of cvs Pokkaliand BRRI Dhan29, the fluorescence resonance energytransfer (FRET) efficiency between VHA-c and VHA-aupon salt stress decreased slightly in cv. Pokkali, butincreased significantly in cv. BRRI Dhan29. The resultssuggest that the salt-tolerant cv. Pokkali regulates theexpression of OsHKT1, OsHKT2, and OsVHA differentlyfrom how the salt-sensitive cv. BRRI Dhan29 does.Together, these proteins might confer salt tolerance inPokkali by maintaining a low cytosolic Na+ level anda correct ratio of cytosolic Na+/K+.
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| 18. |
- Kader, Abdul, 1969-, et al.
(författare)
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Sodium sensing induces different changes in free cytosolic calcium concentration and pH in salt-tolerant and -sensitive rice (Oryza sativa) cultivars
- 2007
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Ingår i: Physiologia Plantarum. - : Blackwell Publishing. - 0031-9317. ; 130, s. 99-111
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Tidskriftsartikel (refereegranskat)abstract
- Perception of salt stress in plant cells induces a change in the free cytosolic Ca2+, [Ca2+]cyt, which transfers downstream reactions toward salt tolerance. Changes in cytosolic H+ concentration, [H+]cyt, are closely linked to the [Ca2+]cyt dynamics under various stress signals. In this study, salt-induced changes in [Ca2+]cyt, and [H+]cyt and vacuolar [H+] concentrations were monitored in single protoplasts of rice (Oryza sativa L. indica cvs. Pokkali and BRRI Dhan29) by fluorescence microscopy. Changes in cytosolic [Ca2+] and [H+] were detected by use of the fluorescent dyes acetoxy methyl ester of calcium-binding benzofuran and acetoxy methyl ester of 2', 7'-bis-(2- carboxyethyl)-5-(and-6) carboxyfluorescein, respectively, and for vacuolar pH, fluorescent 6-carboxyfluorescein and confocal microscopy were used. Addition of NaCl induced a higher increase in [Ca21]cyt in the salt-tolerant cv. Pokkali than in the salt-sensitive cv. BRRI Dhan29. From inhibitor studies, we conclude that the internal stores appear to be the major source for [Ca2+]cyt increase in Pokkali, although the apoplast is more important in BRRI Dhan29. The [Ca21]cyt measurements in rice also suggest that Na1 should be sensed inside the cytosol, before any increase in [Ca2+]cyt occurs. Moreover, our results with individual mesophyll protoplasts suggest that ionic stress causes an increase in [Ca2+]cyt and that osmotic stress sharply decreases [Ca2+]cyt in rice. The [pH]cyt was differently shifted in the two rice cultivars in response to salt stress and may be coupled to different activities of the H1-ATPases. The changes in vacuolar pH were correlated with the expressional analysis of rice vacuolar H+-ATPase in these two rice cultivars.
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| 19. |
- Kader, M Abdul, et al.
(författare)
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Adaptation mechanisms in Rice (Oryza sativa) under salt stress
- 2007
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Ingår i: 2nd World Conference on Stress. ; , s. 1-
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Konferensbidrag (refereegranskat)abstract
- The project focuses on two important aspects of Na+ toxicity in salt-tolerant rice cv. Pokkali and salt-sensitive cv. BRRI Dhan29, namely i) how Na+ stress induces a change in cytosolic Ca2+, [Ca2+]cyt, and pH, [pH]cyt, and ii) how cells could maintain a low cytosolic Na+ and/or Na+/K+ ratio. The salt-induced changes in [Ca2+]cyt and [pH]cyt and their sources were monitored in single rice protoplasts by fluorescence microscopy. The expression of the transporter genes OsHKT1, OsHKT2 and OsVHA, which are thought to play a significant role in maintaining correct cytosolic Na+ and or Na+/K+ ratio, were examined in both rice cultivars under salt stress condition by real time RT-PCR and in situ PCR. The results show that Na+ must be sensed inside the cytosol, before any changes in [Ca2+]cyt and [pH]cyt occur. Sensing of Na+ induced different changes in [Ca2+]cyt and [pH]cyt in the two rice cultivars with different sources for the changes. The [pH]cyt changes were coupled to differentH+-ATPases in the two cultivars. The expression analysis of OsHKT1, OsHKT2 and OsVHA showed variable and cell- specific induction in these cultivars under salt stress condition. The important mechanism for salt tolerance in cv. Pokkali was to keep cytosolic Na+ at a low level, by reducing Na+-influx (through down-regulation of OsHKT1) and compartmentalizing cytosolic Na+ into the vacuole (through the induction of vacuolar H+ATPase OsVHA, an energizer for the tonoplast Na+/H+ antiporter). Pokkali might also induce increased uptake of K+ through the induction of OsHKT2, as evident in this study. Vacuolarcompartmentalization of Na+ is also present in salt-sensitive cv. BRRI Dhan29, but to a lesser extent and much later than in cv. Pokkali. The results suggest that the signaling and subsequent adaptive responses in the salt-tolerant rice cv. Pokkali are different from that in the salt-sensitive cv. BRRI Dhan29.
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| 20. |
- Kader, Md Abdul, et al.
(författare)
-
Cellular traits for sodium tolerance in rice (Oryza sativa L.)
- 2008
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Under salt stress the ability to reduce Na+-influx into the cytosol, and subsequently increase the compartmentalization of cytosolic Na+ into the vacuole, appeared to be the significant salt-tolerance determinant in salt-tolerant cv. Pokkali. These mechanisms were either absent or less efficient in the salt-sensitive cv. BRRI Dhan29.
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| 21. |
- Kader, Md Abdul, et al.
(författare)
-
Cellular traits for sodium tolerance in rice (Oryza sativa L.)
- 2008
-
Ingår i: Plant Biotechnology. ; 25:3, s. 247-255
-
Tidskriftsartikel (refereegranskat)abstract
- AbstractThe present review focuses on two important aspects of Na+ toxicity in rice (Oryza sativa L.), i) that Na+ stress induces different changes in cytosolic Ca2+, [Ca2+]cyt, and pH, [pH]cyt, in tolerant and sensitive cultivars, and ii) that cells from a tolerant cultivar can better maintain a low cytosolic Na+ and/or Na+/K+ ratio. Experiments with single rice protoplasts, fluorescence microscopy and specific ion-selective dyes suggest that Na+ must be sensed inside the cytosol, before any prolonged changes in [Ca2+]cyt and [pH]cyt occur. Inhibitor analyses show that Na+-induced increase in [pH]cyt in the tolerant cv. Pokkali, and a decrease in [pH]cyt in the sensitive cv. BRRI DHan29, likely are coupled to different H+-ATPases. Expression analysis of OsHKT2;1 (previous name OsHKT1), OsHKT2;2 (previous name OsHKT2) and OsVHA transcripts in rice using RT-PCR and fluorescence in situ-PCR, shows a variable and cell- specific induction in the two rice cultivars under salt stress condition. We conclude that the transient uptake of Na+, which occurs only in the tolerant cultivar, and the fast compartmentalization of Na+ into the vacuole, probably are the most important cellular traits for Na+-tolerance in rice. The low [Na+]cyt in cv. Pokkali might depend on the fast down-regulation of OsHKT2;1, causing less uptake of Na+, and fast up-regulation of the OsVHA transcript, and subsequent activation of the Na+/H+-anti-porter in the tonoplast. To decrease the cytosolic Na+/K+ ratio under Na+ toxicity, cv. Pokkali may also induce increased uptake of K+ through induction of OsHKT2;2, and other specific K+-transporter genes.
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| 22. |
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| 23. |
- Kader, Md Abdul, et al.
(författare)
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Mechanisms for cytosolic Na+ homeostasis in rice under salt stress
- 2009
-
Ingår i: Global Challenges in Research Cooperation, May 27-29 2008, Uppsala, Sweden. ; , s. 1-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Under salt stress the ability to reduce Na+-influx into the cytosol, and subsequently increase the compartmentalization into the vacuole, appeared to be the significant salt-tolerance determinants in the salt-tolerant rice, cv. Pokkali. These mechanisms were either absent, or less efficient, in the salt-sensitive rice cv. BRRI Dhan29.
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| 24. |
- Lindberg, Sylvia, et al.
(författare)
-
Cadmium uptake and interaction with phytochelatins in wheat protoplasts : Cadmium uptake and interaction with phytochelatins in wheat protoplasts
- 2007
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Ingår i: Plant Physiology and Biochemistry: Plant Physiology and Biochemistry. ; 45:1, s. 47-53
-
Tidskriftsartikel (refereegranskat)abstract
- In order to investigate the role of phytochelatins in short-time uptake of Cd2+ into the cytosol of wheat protoplasts, a new method wasapplied, using fluorescence microscopy and the heavy metal-specific fluorescent dye, 5-nitrobenzothiazole coumarin, BTC-5N. The uptake of Cd2+ into protoplasts from 5- to 7-day-old wheat seedlings (Triticum aestivum, L. cv. Kadett) was lower in protoplasts from seedlings raised inthe presence of 1 mM CdCl2, than in the absence. Presence of CdCl2 in the cultivation medium increased the content of phytochelatins (PCs) in the protoplasts. When seedlings were raised in the presence of both Cd2+ and buthionine sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, only little PC was found in the protoplasts. Pre-treatment with BSO alone did not affect the content of PC, but inhibited that of GSH. The inhibition of GSH was independent of pre-treatment with Cd2+. Unidirectional flux analyses, using 109Cd2+, showed approximately the same uptake pattern of Cd2+ as did the fluorescence experiments showing the cytosolic uptake of Cd2+. Thus, the diminished uptake of Cd2+ into protoplasts from cadmium-pre-treated plants was not depending on PCs. Instead, it is likely that pre-treatment with Cd2+ causes a down-regulation of the short-term Cd2+ uptake, or an up-regulation of the Cd2+ extrusion. Moreover, since addition of Cd2+ to protoplasts from control plants caused a cytosol acidification, it is likely that a Cd2+/H+-antiport mechanism is involved in the extrusion of Cd2+ from these protoplasts.
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| 25. |
- Lindberg, Sylvia, et al.
(författare)
-
Calcium signalling in plant cells under environmental stress
- 2011. - 1
-
Ingår i: Environmental adaptations and stress tolerance of plants in the era of climate change. - New york, NY : Springer. - 9781461408154 ; , s. 325-360
-
Bokkapitel (refereegranskat)abstract
- A change of intracellular calcium concentration is an early event in a large array of biological processes in plants, such as cell division, polarity, growth and development at normal conditions and under adaptation to abiotic and biotic stresses. This chapter will focus on calcium signaling induced by different types of abiotic stress, such as salt, cold, anoxia, aluminium and heavy metal stresses. A minor part deals with biotic stress signaling. Most investigations, so far, concerned Ca2+ signaling in the cytosol, but the last years also signaling in the nucleus and other cell compartments such as mitochondria, ER and cell wall have been reported. We will compare the specific “signature” of calcium, including duration, amplitude and frequency of the signaling, which is induced by different stresses and is important for a change of the physiological function. Different stores for calcium take part in the signaling under various types of stresses. Of special interest is a comparison of signaling in tolerant and sensitive species and cultivars.
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| 26. |
- Lindberg, Sylvia, 1945-, et al.
(författare)
-
Ion Changes and Signaling under Salt Stress in Wheat and Other Important Crops
- 2024
-
Ingår i: PLANTS. - 2223-7747. ; 13:1
-
Forskningsöversikt (refereegranskat)abstract
- High concentrations of sodium (Na+), chloride (Cl-), calcium (Ca2+), and sulphate (SO42-) are frequently found in saline soils. Crop plants cannot successfully develop and produce because salt stress impairs the uptake of Ca2+, potassium (K+), and water into plant cells. Different intracellular and extracellular ionic concentrations change with salinity, including those of Ca2+, K+, and protons. These cations serve as stress signaling molecules in addition to being essential for ionic homeostasis and nutrition. Maintaining an appropriate K+:Na+ ratio is one crucial plant mechanism for salt tolerance, which is a complicated trait. Another important mechanism is the ability for fast extrusion of Na+ from the cytosol. Ca2+ is established as a ubiquitous secondary messenger, which transmits various stress signals into metabolic alterations that cause adaptive responses. When plants are under stress, the cytosolic-free Ca2+ concentration can rise to 10 times or more from its resting level of 50-100 nanomolar. Reactive oxygen species (ROS) are linked to the Ca2+ alterations and are produced by stress. Depending on the type, frequency, and intensity of the stress, the cytosolic Ca2+ signals oscillate, are transient, or persist for a longer period and exhibit specific signatures. Both the influx and efflux of Ca2+ affect the length and amplitude of the signal. According to several reports, under stress Ca2+ alterations can occur not only in the cytoplasm of the cell but also in the cell walls, nucleus, and other cell organelles and the Ca2+ waves propagate through the whole plant. Here, we will focus on how wheat and other important crops absorb Na+, K+, and Cl- when plants are under salt stress, as well as how Ca2+, K+, and pH cause intracellular signaling and homeostasis. Similar mechanisms in the model plant Arabidopsis will also be considered. Knowledge of these processes is important for understanding how plants react to salinity stress and for the development of tolerant crops.
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| 27. |
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| 28. |
- Lindberg, Sylvia, et al.
(författare)
-
Phospholipases AtPLD1 and AtPLD2 function differently in hypoxia
- 2018
-
Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 162:1, s. 98-108
-
Tidskriftsartikel (refereegranskat)abstract
- Besides hydrolyzing different membrane phospholipids, plant phospholipases D and molecular species of their byproducts phosphatidic acids (PLDs/PAs) are involved in diverse cellular events such as membrane-cytoskeleton dynamics, hormone regulation and biotic and/or abiotic stress responses at cellular or subcellular levels. Among the 12 Arabidopsis PLD genes, PLD1 and PLD2 uniquely possess Ca2+-independent phox (PX) and pleckstrin (PH) homology domains. Here, we report that mutants deficient in these PLDs, pld1 and pld2, show differential sensitivities to hypoxia stimulus. In the present study, we used protoplasts of wild type and mutants and compared the hypoxia-induced changes in the levels of three major signaling mediators such as cytoplasmic free calcium [Ca-cyt.(2+)], hydrogen peroxide (H2O2) and PA. The concentrations of cytosolic Ca2+ and H2O2 were determined by fluorescence microscopy and the fluorescent dyes Fura 2-AM and CM-H(2)DCFDA, specific for calcium and H2O2, respectively, while PA production was analyzed by an enzymatic method. The study reveals that AtPLD1 is involved in reactive oxygen species (ROS) signaling, whereas AtPLD2 is involved in cytosolic Ca2+ signaling pathways during hypoxic stress. Hypoxia induces an elevation of PA level both in Wt and pld1, while the PA level is unchanged in pld2. Thus, it is likely that AtPLD2 is involved in PA production by a calcium signaling pathway, while AtPLD1 is more important in ROS signaling.
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| 29. |
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| 30. |
- Morgan, Sherif H., et al.
(författare)
-
Calcium improves apoplastic-cytosolic ion homeostasis in salt-stressed Vicia faba leaves
- 2017
-
Ingår i: Functional Plant Biology. - 1445-4408 .- 1445-4416. ; 44:5, s. 515-524
-
Tidskriftsartikel (refereegranskat)abstract
- Salinity disturbs both apoplastic and cytosolic Ca2+ and pH ([Ca2+](apo), [Ca2+](cyt), pH(apo) and pH(cyt)) homeostasis, and decreases plant growth. Seedlings of Vicia faba L. cv. Fuego were cultivated in hydroponics for 7 days under control, salinity (S), extra Ca (Ca) or salinity with extra Ca (S+Ca) conditions. The [Ca2+](apo), and pH(apo) in the leaves were then recorded in parallel by a pseudoratiometric method, described here for the first time. Lower [Ca2+](apo) and higher pH(apo) were obtained under salinity, whereas extra Ca supply increased the [Ca2+](apo) and acidified the pH(apo). Moreover, the ratiometric imaging recorded that [Ca2+](cyt) and pH(cyt) were highest in S+Ca plants and lowest in control plants. After all pretreatments, direct addition of NaC6H11O7 to leaves induced a decrease in [Ca2+](apo) in control and S+Ca plants, but not in S and Ca plants, and only slightly affected pH(apo). Addition of NaCl increased [Ca2+](cyt) in protoplasts from all plants but only transiently in protoplasts from S+Ca plants. Addition of NaCl decreased pH(cyt) in protoplasts from Ca-pretreated plants. We conclude that Ca supply improves both apoplastic and cytosolic ion homeostasis. In addition, NaC6H11O7 probably causes transport of Ca from the apoplast into the cytosol, thereby leading to a higher resting [Ca2+](cyt).
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| 31. |
- Morgan, Sherif H., et al.
(författare)
-
Calcium supply effects on wheat cultivars differing in salt resistance with special reference to leaf cytosol ion homeostasis
- 2013
-
Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 149:3, s. 321-328
-
Tidskriftsartikel (refereegranskat)abstract
- Salinity causes changes in cytosolic Ca2+, [Ca2+](cyt), Na+, [Na+](cyt) and pH, pH(cyt), which induce specific reactions and signals. Reactions causing a rebalancing of the physiological homeostasis of the cytosol could result in plant resistance and growth. Two wheat cultivars, Triticum aestivum, Seds1 and Vinjett, were grown in nutrient solution for 7days under moderate salinity (0 and 50mMNaCl) with and without extra addition of 5mMCaSO(4) to investigate the seedling-ion homeostasis under salinity. In the leaf protoplasts [Ca2+](cyt), [Na+](cyt) and pH(cyt) were detected using acetoxymethyl esters of the ion-specific dyes, Fura 2, SBFI and BCECF, respectively, and fluorescence microscopy. In addition, both cultivars were grown for 3weeks at 0, 50 and 125mMNaCl with, or without, extra addition of 5mMCaSO(4) to detect overall Na+ and Ca2+ concentrations in leaves and salinity effects on dry weights. In both cultivars, salinity decreased [Ca2+](cyt), while at extra Ca2+ supplied, [Ca2+](cyt) increased. The [Ca2+](cyt) increase was accompanied by increase in the overall Ca2+ concentrations in leaves and decrease in the overall Na+ concentration. Moreover, irrespective of Ca2+ treatment under salinity, the cultivars reacted in different ways; [Na+](cyt) significantly increased only in cv. Vinjett, while pH(cyt) increased only in cv. Seds1. Even at rather high total Na+ concentrations, the cytosolic concentrations were kept low in both cultivars. It is discussed whether the increase of [Ca2+](cyt) and pH(cyt) can contribute to salt tolerance and if the cytosolic changes are due to changes in overall Ca2+ and Na+ concentrations.
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| 32. |
- Morgan, Sherif H., et al.
(författare)
-
Cytosolic Sodium Influx in Mesophyll Protoplasts of Arabidopsis thaliana, wt, sos1:1 and nhx1 Differs and Induces Different Calcium Changes
- 2022
-
Ingår i: PLANTS. - : MDPI AG. - 2223-7747. ; 11:24
-
Tidskriftsartikel (refereegranskat)abstract
- The sodium influx into the cytosol of mesophyll protoplasts from Arabidopsis thaliana cv. Columbia, wild type, was compared with the influx into sos1-1 and nhx1 genotypes, which lack the Na+/H+ antiporter in the plasma membrane and tonoplast, respectively. Changes in cytosolic sodium and calcium concentrations upon a 100 mM NaCl addition were detected by use of epifluorescence microscopy and the sodium-specific fluorescent dye SBFI, AM, and calcium sensitive Fura 2, AM, respectively. There was a smaller and mainly transient influx of Na+ in the cytosol of the wild type compared with the sos1-1 and nhx1 genotypes, in which the influx lasted for a longer time. Sodium chloride addition to the protoplasts’ medium induced a significant increase in cytosolic calcium concentration in the wild type at 1.0 mM external calcium, and to a lesser extent in nhx1, however, it was negligible in the sos1-1 genotype. LiCl inhibited the cytosolic calcium elevation in the wild type. The results suggest that the salt-induced calcium elevation in the cytosol of mesophyll cells depends on an influx from both internal and external stores and occurs in the presence of an intact Na+/H+ antiporter at the plasma membrane. The Arabidopsis SOS1 more effectively regulates sodium homeostasis than NHX1.
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| 33. |
- Morgan, Sherif H., et al.
(författare)
-
Leaf ion homeostasis and plasma membrane H+-ATPase activity in Vicia faba change after extra calcium and potassium supply under salinity
- 2014
-
Ingår i: Plant physiology and biochemistry (Paris). - : Elsevier BV. - 0981-9428 .- 1873-2690. ; 82, s. 244-253
-
Tidskriftsartikel (refereegranskat)abstract
- Salt stress in plants impacts apoplastic ion activities and cytosolic ionic homeostasis. The ameliorating effects exerted by calcium or potassium on compartmentation of ions in leaves under salinity are not fully understood. To clarify how calcium or potassium supply could ameliorate ion homeostasis and ATPase activities under salinity, 5 mM CaSO4 or 10 mM K2SO4 were added with, or without, 100 mM NaCl for 7 d and 21 d to Vicia faba grown in hydroponics. The apoplastic pH was detected with Oregon Green dextran dye in intact second-uppermost leaves by microscopy-based ratio imaging. The cytosolic Ca2+, Na+, K+ activities and pH were detected in protoplasts loaded with the acetoxy methyl-esters of Fura-2, SBFI, PBFI and BCECF, respectively, using epi-fluorescence microscopy. Furthermore, total Ca2+, Na+, K+ concentrations and growth parameters were investigated. The ATPase hydrolyzing activity increased with time, but decreased after long salinity treatment. The activity largely increased in calcium-treated plants, but was depressed in potassium-treated plants after 7 d. The calcium supply increased Vmax, and the ATPase activity increased with salinity in a non-competitive way for 7 d and 21 d. The potassium supply instead decreased activity competitively with Na+, after 21 d of salinity, with different effects on Km and Vmax. The confirmed higher ATPase activity was related with apoplast acidification, cytosol alkalinization and low cytosolic [Na+], and thus, might be an explanation why extra calcium improved shoot and leaf growth.
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| 34. |
- Premkumar, Albert, et al.
(författare)
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Arabidopsis PLDs with C2-domain function distinctively in hypoxia
- 2019
-
Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 167:1, s. 90-110
-
Tidskriftsartikel (refereegranskat)abstract
- Hypoxia (oxygen deprivation) causes metabolic disturbances at physiological, biochemical and genetic levels and results in decreased plant growth and development. Phospholipase D (PLD)-mediated signaling was reported for abiotic and biotic stress signaling events in plants. To investigate the participatory role of PLDs also in hypoxia signaling, we used wild type of Arabidopsis thaliana and 10 pld isoform mutants containing C2-domain. Hypoxia-induced changes in three major signaling players, namely, cytosolic free calcium (Ca-cyt(2+)), reactive oxygen species (ROS) and phosphatidic acid (PA), were determined in mesophyll protoplasts. The Ca-cyt(2+) and ROS levels were monitored by fluorescence microscopy and confocal imaging, while PA levels were quantified by an enzymatic method. Our findings reveal that the elevations of cytosolic calcium and PA are reduced in all the 10 mutants dysfunctional in PLD isoforms. The hypoxia-related changes in both calcium and ROS show different kinetic patterns depending on the type of PLD studied. Pharmacological experiments confirm that both external and internal sources contribute to calcium and ROS accumulation under hypoxia. PLD alpha 1-3, PLD beta 1 and PLD gamma 1-3 are likely involved in calcium signaling under hypoxia as well as in PA production, while all investigated PLDs, except for PLD gamma 3, take part in ROS elevation.
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| 35. |
- Premkumar, Albert, et al.
(författare)
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Silicate Inhibits the Cytosolic Influx of Chloride in Protoplasts of Wheat and Affects the Chloride Transporters, TaCLC1 and TaNPF2.4/2.5
- 2022
-
Ingår i: PLANTS. - : MDPI AG. - 2223-7747. ; 11:9
-
Tidskriftsartikel (refereegranskat)abstract
- Chloride is an essential nutrient for plants, but high concentrations can be harmful. Silicon ameliorates both abiotic and biotic stresses in plants, but it is unknown if it can prevent cellular increase of chloride. Therefore, we investigated the influx of Cl− ions in two wheat cultivars different in salt sensitivity, by epifluorescence microscopy and a highly Cl−-sensitive dye, MQAE, N-[ethoxycarbonylmethyl]-6-methoxy-quinolinium bromide, in absence and presence of potassium silicate, K2SiO3. The Cl−-influx was higher in the salt-sensitive cv. Vinjett, than in the salt-tolerant cv. S-24, and silicate pre-treatment of protoplasts inhibited the Cl−-influx in both cultivars, but more in the sensitive cv. Vinjett. To investigate if the Cl−-transporters TaCLC1 and TaNPF2.4/2.5 are affected by silicate, expression analyses by RT-qPCR were undertaken of TaCLC1 and TaNPF 2.4/2.5 transcripts in the absence and presence of 100 mM NaCl, with and without the presence of K2SiO3. The results show that both transporter genes were expressed in roots and shoots of wheat seedlings, but their expressions were differently affected by silicate. The TaNPF2.4/2.5 expression in leaves was markedly depressed by silicate. These findings demonstrate that less chloride accumulates in the cytosol of leaf mesophyll by Si treatment and increases salt tolerance.
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| 36. |
- Shahid, M., et al.
(författare)
-
Serratia sp. CP-13 augments the growth of cadmium (Cd)-stressed Linum usitatissimum L. by limited Cd uptake, enhanced nutrient acquisition and antioxidative potential
- 2019
-
Ingår i: Journal of Applied Microbiology. - : Oxford University Press (OUP). - 1364-5072 .- 1365-2672. ; 126:6, s. 1708-1721
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: The current study was aimed to evaluate the beneficial effects and bioremediation potential of a Cd-tolerant bacterial strain, Serratia sp. CP-13, on the physiological and biochemical functions of Linum usitatissimum L., under Cd stress.Methods and Results: The bacterial strain was isolated from the wastewater collection point of Chakera, Faisalabad, Pakistan, as this place contains industrial wastewater of the Faisalabad region. The Serratia sp. CP-13, identified through 16S rRNA gene sequence analysis, exhibited a significant phyto-beneficial potential in terms of in vitro inorganic phosphate solubilization, indole-3-acetic acid production and 1-aminocyclopropane-1-carboxylic acid deaminase activity. Effects of Serratia sp. CP-13 inoculation on L. usitatissimum were evaluated by growing the plants in CdCl2 (0, 5 or 10 mg kg(-1) dry soil)-spiked soil. Without inoculation of Serratia sp. CP-13, Cd stress significantly reduced the plant biomass as well as the quantity of proteins and photosynthetic pigments due to enhanced H2O2, malondialdehyde (MDA) contents and impaired nutrient homeostasis. Subsequently, Serratia sp. CP-13 increased the plant fresh and dry biomass, plant antioxidation capacity, whereas it decreased the lipid peroxidation under Cd stress. In parallel, Serratia sp. inoculation assisted the Cd-stressed plants to maintain an optimum level of nutrients (K, Ca, P, Mg, Fe and Mn).Conclusions: The isolated bacterial strain (Serratia sp. CP-13) when applied to Cd-stressed L. usitatissimum inhibited the Cd uptake, reduced Cd-induced lipid peroxidation, maintained the optimum level of nutrients and thereby, enhanced L. usitatissimum growth. The analysis of bio-concentration and translocation factor revealed that L. usitatissimum with Serratia sp. CP-13 inoculation sequestered Cd in plant rhizospheric zone.Significance and Impact of the Study: Serratia sp. CP-13 inoculation is a potential candidate for the development of low Cd-accumulating linseed and could be used for phytostabilization of Cd-contaminated rhizosphere/soil colloids.
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| 37. |
- Shishova, Maria, et al.
(författare)
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A new perspective on auxin perception
- 2010
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Ingår i: Journal of plant physiology (Print). - : Elsevier. - 0176-1617 .- 1618-1328. ; 167:6, s. 417-422
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Tidskriftsartikel (refereegranskat)abstract
- An important question in modern plant biology concerns the mechanisms of auxin perception. Despite the recently discovered soluble receptor, the F-box protein TIR1, there is no doubt that another type of signal perception exists, and is linked to the plasma membrane. Two models for the receptor have been suggested: either the receptor includes a protein kinase, or it is coupled with a G-protein. We propose a third model, acting through Ca2+-channels in the plasma membrane. The model is based on the revealed rapid auxin-induced reactions, including changes in the membrane potential, shifts in cytosol concentration of Ca2+ and H+ and modulation of cell sensitivity to hormones by the external Ca2+ concentration. Detailed inhibitor analysis with both living cells and isolated plasma membranes show that auxin might directly stimulate Ca2+ transport through the plasma membrane. A hypothetical scheme of auxin perception at the plasma membrane is suggested together with further transduction events. In addition, comparative analyses of auxin and serotonin perceptions are provided.
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| 38. |
- Shishova, Maria, et al.
(författare)
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A shift in sensitivity to auxin within development of maize seedlings
- 2007
-
Ingår i: Journal of Plant Physiology. ; 164, s. 1323-1330
-
Tidskriftsartikel (refereegranskat)abstract
- The auxin-induced changes in cytosolic concentrations of Ca2+ and H+ ions were investigated in protoplasts from maize coleoptile cells at 3rd, 4th and 5th day of development of etiolated seedlings. The shifts in [Ca2+]cyt and [H+]cyt were detected by use of fluorescence microscopy in single protoplasts loaded with the tetra[acetoxymethyl]esters of the fluorescent calcium binding Fura 2, or pH-sensitive carboxy-fluorescein, BCECF, respectively. Both the auxin-induced shifts in the ion concentrations were specific to the physiologically active synthetic auxin, naphthalene-1-acetic acid (1-NAA), and not to the non-active naphthalene-2-acetic acid (2-NAA). Regardless of the age of the seedlings, the rise in [Ca2+]cyt was prior to the acidification in all investigated cases. The maximal acidification coincided with the highest amplitude of [Ca2+]cyt change, but not directly depended on the concentration of 1-NAA. Within aging of the seedlings the amplitude of auxin-induced [Ca2+]cyt elevation decreased. The shift in auxin-induced acidification was almost equal at 3rd and 4th day, but largely dropped at 5th day of development. The acidification was related to changes in the plasmamembrane H+-ATPase activity, detected as phosphate release. The decrement in amplitude of both the tested auxin-triggered reactions well coincided with the end of the physiological function of the coleoptile. Hence the primary auxin-induced increase in [Ca2+]cyt, which is supposed to be an important element of hormone signal perceptionand transduction, can be used as a test for elucidation of plant cell sensitivity to auxin.
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| 39. |
- Sun, Yujie, et al.
(författare)
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A comparative analysis of cytosolic Na+ changes under salinity between halophyte quinoa (Chenopodium quinoa) and glycophyte pea (Piswn sativwn)
- 2017
-
Ingår i: Environmental and Experimental Botany. - : Elsevier BV. - 0098-8472 .- 1873-7307. ; 141, s. 154-160
-
Tidskriftsartikel (refereegranskat)abstract
- Sodium (Na+) uptake into the halophyte quinoa (Chenopodium quinoa Willd.) plants was compared with the uptake into pea (Pisum sativum L.), and related to changes in cytosolic pH and potassium (K+) concentration in plant tissues. The total uptake of Na+ and K+ in roots and shoots was analyzed and compared with net ion fluxes at the root xylem parenchyma, determined by ion-specific microelectrodes in a non-invasive way. The cytosolic changes of Na+ concentration, [Na-cyt(+)], and pH, pH(cyt), were measured by fluorescent probes, specific to Na+ and H+, using a dual-wavelength fluorescence microscopy. These changes were monitored in protoplasts after cultivation with or without 100 mM NaCl, and after addition of NaC1 to the protoplasts. Roots and shoots of quinoa controls contained much higher K+ levels than pea roots and shoots, and the K+ levels increased even more after salinity treatments in quinoa. The cytosolic uptake of Na+ in quinoa protoplasts was transient if less than 200 mM NaCl was added, while in pea the Na+ concentration increased even upon addition of 50 mM Na+ and gradually increased with time. Saline conditions during cultivation increased pH(cyt) of both species. However, with a direct addition of NaCl to control protoplasts only a small increase was seen in pea pH(cyt) while in quinoa this increase was much larger. The different reactions of pH(cyt) to salinity when NaCl was added to salinity-treated seedlings may reflect an increased proton pump activity in quinoa, while this activation is lacking in pea. ABA addition to the root xylem parenchyma cells induced a net efflux of K+ and acidification of the xylem. On the other hand, 20 mM NaC1 addition induced a net flux of protons in both species, and a net K+ flux in pea, but not in quinoa, probably since such a low concentration is not a stress for quinoa. It is suggested that salinity tolerance in quinoa is achieved by a faster removal of Na+ from the cytosol and a high K+ concentration in roots and shoots under salinity, resulting in a high K+/Na+ ratio, and that this mechanism is driven by a higher proton pump activity, compared with glycophytic pea species.
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| 40. |
- Tanwir, Kashif, et al.
(författare)
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Cadmium-induced rhizospheric pH dynamics modulated nutrient acquisition and physiological attributes of maize (Zea mays L.)
- 2015
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Ingår i: Environmental Science and Pollution Research. - : Springer Science and Business Media LLC. - 0944-1344 .- 1614-7499. ; 22:12, s. 9193-9203
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Tidskriftsartikel (refereegranskat)abstract
- Cadmium (Cd) is a highly mobile toxic element in soil-plant systems that interferes with plant growth and nutrient acquisition by modulations in the rhizospheric environment. The current study investigated the influence of maize roots on the medium pH, alterations in nutrient uptake, and impact on the plant's physiological attributes under Cd stress. Among the nine maize cultivars, subjected to Cd stress (9.15 mg/kg of sand), one was identified as Cd tolerant (3062-Pioneer) and the second as Cd sensitive (31P41-Pioneer). The selected maize cultivars were grown in nutrient solutions supplemented with 0, 10, 20, 30, 40, or 50 mu M CdCl2 under controlled conditions and a starting pH of 6.0. The rhizospheric pH dynamics were monitored each day up to 3 days. Both cultivars caused medium basification; however, the response was different at low (10 and 20 mu M) Cd treatments (sensitive cultivar caused medium basification) and at higher (50 mu M) Cd treatment (tolerant cultivar caused medium basification). Furthermore, higher Cd was accumulated by the sensitive cultivar which was predominantly found in the roots. Higher Cd levels in the medium resulted in increased uptake and translocation of both Cd and K (in the tolerant cultivar) or only Cd (in the sensitive cultivar). Uptake of other nutrients (Ca, Zn, and Fe) was antagonistically affected by Cd stress in both cultivars. Moreover, Cd stress significantly impaired chlorophyll content, catalase activity, and total protein content; irrespective of the genotype. The malondialdehyde (MDA) content was found to increase, in both cultivars, together with Cd level. However, the extent to which Cd interfered with the studied attributes was more pronounced in the sensitive cultivar as compared to the tolerant one. It is concluded that the maize roots responded to Cd stress by initiating modulations of medium pH which might be dependent on Cd tolerance levels. The study results may help to develop strategies to reduce Cd accumulation in maize and decontamination of metal-polluted soil sediments.
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| 41. |
- Tanwir, Kashif, et al.
(författare)
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Ecophysiology and Stress Responses of Aquatic Macrophytes Under Metal/Metalloid Toxicity
- 2020
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Ingår i: Plant Ecophysiology and Adaptation under Climate Change: Mechanisms and Perspectives I. - Singapore : Springer. - 9789811521553 - 9789811521584 - 9789811521560 ; , s. 485-511
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Bokkapitel (refereegranskat)abstract
- Many metal elements are essential for plant growth at low concentrations but their excessive levels in the rhizosphere may cause phytotoxicity depending upon the fact that metals are easily absorbed and translocated in soil–plant systems. Nonessential metals/metalloids, i.e., Pb, Cr, Cd, As, Hg, etc., initiate a series of consecutive and/or parallel events at morphological, physiological, and molecular levels in aquatic plants depending on the nature of element and plant species. This chapter emphasizes the responses of aquatic macrophytes to metals/metalloids, with possible implementation in phytoremediation techniques. Metal-triggered growth inhibition, alterations in enzyme activities, inhibition of photosynthesis, changes in nutrient acquisition and metabolism, and the formation of free radicals are the major components reviewed in this book chapter. Discussion about the metal toxicity avoidance strategies like fluctuations in rhizospheric environments, plasma membrane exclusion, cell wall immobilization, phytochelatin-based sequestration and compartmentalization processes, stress proteins, and metallothioneins is also within the scope of this chapter. Metal tolerance in aquatic plants is more likely involved in an integrated network of multiple response processes generally described as “fan-shaped response” rather than several isolated functions described above. Plant tolerance to metals/metalloids is mainly determined from its transport across plasma membrane and tonoplast in plant. The appropriate understanding of metal-triggered ecophysiological responses of aquatic plants may make it promising to use them for treatment of metal polluted waters and soils.
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| 42. |
- Yemelyanov, Vladislav, et al.
(författare)
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Anoxia-induced elevation of cytosolic Ca2+ concentration depends on different Ca2+ sources in rice and wheat protoplasts
- 2011
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Ingår i: Planta. - : Springer. - 0032-0935 .- 1432-2048. ; 234, s. 271-280
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Tidskriftsartikel (refereegranskat)abstract
- The anoxia-dependent elevation of cytosolicCa2+ concentration, [Ca2+]cyt, was investigated in plants differing in tolerance to hypoxia. The [Ca2+]cyt was measuredby fluorescence microscopy in single protoplastsloaded with the calcium-fluoroprobe Fura 2-AM. Imposition of anoxia led to a fast (within 3 min) significant elevationof [Ca2+]cyt in rice leaf protoplasts. A tenfold drop in the external Ca2+ concentration (to 0.1 mM) resulted inconsiderable decrease of the [Ca2+]cyt shift. Rice root protoplasts reacted upon anoxia with higher amplitude. Addition of plasma membrane (verapamil, La3+ and EGTA) and intracellular membrane Ca2+-channel antagonists(Li+, ruthenium red and cyclosporine A) reduced the anoxic Ca2+-accumulation in rice. Wheat protoplasts responded to anoxia by smaller changes of [Ca2+]cyt. In wheat leaf protoplasts, the amplitude of the Ca2+-shift little depended on the external level of Ca2+. Wheat root protoplasts were characterized by a small shift of [Ca2+]cyt under anoxia. Plasmalemma Ca2+-channel blockers had little effect on the elevation of cytosolic Ca2+ in wheat protoplasts. Intact rice seedlings absorbed Ca2+ from the external medium under anoxic treatment. On the contrary,wheat seedlings were characterized by leakage of Ca2+. Verapamil abolished the Ca2?+influx in rice roots and Ca2+ efflux from wheat roots. Anoxia-induced [Ca2+]cyt elevation was high particularly in rice, a hypoxia-tolerant species. In conclusion, both external and internal Ca2+ stores are important for anoxic [Ca2+]cyt elevation in rice, whereas the hypoxia-intolerant wheat does not requireexternal sources for [Ca2+]cyt rise. Leaf and root protoplasts similarly responded to anoxia, independent of theirorgan origin.
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| 43. |
- Yemelyanov, Vladislav V., et al.
(författare)
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Indoleacetic Acid Levels in Wheat and Rice Seedlings under Oxygen Deficiency and Subsequent Reoxygenation
- 2020
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Ingår i: Biomolecules. - : MDPI AG. - 2218-273X. ; 10:2
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Tidskriftsartikel (refereegranskat)abstract
- The lack of oxygen and post-anoxic reactions cause significant alterations of plant growth and metabolism. Plant hormones are active participants in these alterations. This study focuses on auxin-a phytohormone with a wide spectrum of effects on plant growth and stress tolerance. The indoleacetic acid (IAA) content in plants was measured by ELISA. The obtained data revealed anoxia-induced accumulation of IAA in wheat and rice seedlings related to their tolerance of oxygen deprivation. The highest IAA accumulation was detected in rice roots. Subsequent reoxygenation was accompanied with a fast auxin reduction to the control level. A major difference was reported for shoots: wheat seedlings contained less than one-third of normoxic level of auxin during post-anoxia, while IAA level in rice seedlings rapidly recovered to normoxic level. It is likely that the mechanisms of auxin dynamics resulted from oxygen-induced shift in auxin degradation and transport. Exogenous IAA treatment enhanced plant survival under anoxia by decreased electrolyte leakage, production of hydrogen peroxide and lipid peroxidation. The positive effect of external IAA application coincided with improvement of tolerance to oxygen deprivation in the 35S:iaaM x 35S:iaaH lines of transgene tobacco due to its IAA overproduction.
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| 44. |
- Yemelyanov, Vladislav V., et al.
(författare)
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Potassium Efflux and Cytosol Acidification as Primary Anoxia-Induced Events in Wheat and Rice Seedlings
- 2020
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Ingår i: PLANTS. - : MDPI AG. - 2223-7747. ; 9:9
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Tidskriftsartikel (refereegranskat)abstract
- Both ion fluxes and changes of cytosolic pH take an active part in the signal transduction of different environmental stimuli. Here we studied the anoxia-induced alteration of cytosolic K+ concentration, [K+]cyt, and cytosolic pH, pHcyt, in rice and wheat, plants with different tolerances to hypoxia. The [K+]cyt and pHcyt were measured by fluorescence microscopy in single leaf mesophyll protoplasts loaded with the fluorescent potassium-binding dye PBFI-AM and the pH-sensitive probe BCECF-AM, respectively. Anoxic treatment caused an efflux of K+ from protoplasts of both plants after a lag-period of 300–450 s. The [K+]cyt decrease was blocked by tetraethylammonium (1 mM, 30 min pre-treatment) suggesting the involvement of plasma membrane voltage-gated K+ channels. The protoplasts of rice (a hypoxia-tolerant plant) reacted upon anoxia with a higher amplitude of the [K+]cyt drop. There was a simultaneous anoxia-dependent cytosolic acidification of protoplasts of both plants. The decrease of pHcyt was slower in wheat (a hypoxia-sensitive plant) while in rice protoplasts it was rapid and partially reversible. Ion fluxes between the roots of intact seedlings and nutrient solutions were monitored by ion-selective electrodes and revealed significant anoxia-induced acidification and potassium leakage that were inhibited by tetraethylammonium. The K+ efflux from rice was more distinct and reversible upon reoxygenation when compared with wheat seedlings.
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| 45. |
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| 46. |
- Zanella, Letizia, et al.
(författare)
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Overexpression of AtPCS1 in tobacco increases arsenic and arsenic plus cadmium accumulation and detoxification
- 2016
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Ingår i: Planta. - : Springer Science and Business Media LLC. - 0032-0935 .- 1432-2048. ; 243:3, s. 605-622
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Tidskriftsartikel (refereegranskat)abstract
- Main conclusion The heterologous expression of AtPCS1 in tobacco plants exposed to arsenic plus cadmium enhances phytochelatin levels, root As/Cd accumulation and pollutants detoxification, but does not prevent root cyto-histological damages. High phytochelatin (PC) levels may be involved in accumulation and detoxification of both cadmium (Cd) and arsenic (As) in numerous plants. Although polluted environments are frequently characterized by As and Cd coexistence, how increased PC levels affect the adaptation of the entire plant and the response of its cells/tissues to a combined contamination by As and Cd needs investigation. Consequently, we analyzed tobacco seedlings overexpressing Arabidopsis phytochelatin synthase1 gene (AtPCS1) exposed to As and/or Cd, to evaluate the levels of PCs and As/Cd, the cyto-histological modifications of the roots and the Cd/As leaf extrusion ability. When exposed to As and/or Cd the plants overexpressing AtPCS1 showed higher PC levels, As plus Cd root accumulation, and detoxification ability than the non-overexpressing plants, but a blocked Cd-extrusion from the leaf trichomes. In all genotypes, As, and Cd in particular, damaged lateral root apices, enhancing cell-vacuolization, causing thinning and stretching of endodermis initial cells. Alterations also occurred in the primary structure region of the lateral roots, i. e., cell wall lignification in the external cortex, cell hypertrophy in the inner cortex, crushing of endodermis and stele, and nuclear hypertrophy. Altogether, As and/or Cd caused damage to the lateral roots (and not to the primary one), with such damage not counteracted by AtPCS1 overexpression. The latter, however, positively affected accumulation and detoxification to both pollutants, highlighting that Cd/As accumulation and detoxification due to PCS1 activity do not reduce the cyto-histological damage.
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