Effects of Al on nitrogen (NH 4 + and NO 3 − ) uptake, nitrate reductase activity and proton release in two sorghum cultivars differing in Al tolerance

Keltjens, Willem G.; Ulden, P. S. R. van

doi:10.1007/bf02372536

Cited by 64 publications

(39 citation statements)

References 23 publications

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“…Results on Al effects on proton extrusion measured in vivo on Triticum aestivum roots are somewhat contradictory because Kinraide (1988) reported undiminished proton extrusion, while Miyasaka et al (1989) observed inhibition of net H"" efflux in an Al-sensitive (but not in an Al-tolerant) cultivar. In other in vivo experiments, Al increased net H^ efflux from Zea mays roots (Bennet et al, 1987) and also in Sorghum bicolor concomitantly with increased NH4"â nd decreased NO3" uptake (Keltjens & Ulden, 1987). Even though in experiments in vivo the composition of nutrient solution in which plants were grown might have masked the real effect of Al on H^-ATPase activity by influencing cation/anion uptake ratio, it appears that the hypothesis of Al interference with wall acidification through direct effect on H"^-ATPases that would result in reduction of the amount of H^ ions pumped into the apoplasm may not be valid.…”

Section: Cell Wall Extensibilitymentioning

confidence: 66%

Role of calcium in aluminium toxicity

1992

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summary Aluminium is the most important growth‐limiting factor in many acid soils throughout the world. Physiological effects of Al toxicity and mechanisms of tolerance are not well understood. An initial uptake of Al is confined to the apoplasm. Aluminium complexes (whose exact identification is beyond current experimental techniques) enter the cytosol slowly and only after prolonged exposure. Electrochemical properties of the cell wall Donnan free space as well as the plasma membrane of root cells are altered by the presence of Al ions that are polyvalent cations in acidic environments. The primary Al effects are very fast (taking only seconds to several minutes to develop) and may therefore occur while Al is still in the Donnan free space and on the apoplasmic side of the plasma membrane. Resumption of root growth upon removal of Al ions supports such a claim. Aluminium affects membrane permeability for both electrolytes and non‐electrolytes; it reduces accumulation of divalent cations (especially Ca and Mg) by interfering with the membrane transport. Aluminium alters the pattern of Ca2+ fluxes across the plasma membrane, thus supposedly disturbing symplasmic Ca2+ homeostasis. Supplemental Ca2+ can greatly alleviate deleterious Al effects. Frequently observed changes in the secretory activity of root cells exposed to Al are mediated through altered cell Ca2+ homeostasis; they result in cessation of cell wall growth and stoppage of root elongation. Involvement of calmodulin in the Al‐related phenomena is suggested to be indirect, at least in the initial stages of the Al treatment when Al is likely to be confined to the apoplasm. The role of growth substances, at least auxins and cytokinins, in the Al toxicity syndrome appears to be related to the Ca‐Al interactions that may alter the pattern of auxin transport as well as cytokinin biosynthesis and transport. Disturbance of the cell Ca2+ homeostasis appears to be an important feature of ion‐related environmental stresses in general (salt, heavy metals, aluminium).

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Section: Cell Wall Extensibilitymentioning

confidence: 66%

Role of calcium in aluminium toxicity

1992

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“…A similar increase in the amount of Al per unit root length was observed only in the sensitive cv. This form of expression takes account of the change in root system morphology and reflects more closely the surface phenomena associated with Al toxicity (Keltjens & van Ulden, 1987). The Al content increase per unit root length observed in the sensitive cv, as root biomass per unit root length decreases slightly (see Fig.…”

Section: Differences Between Al-sensitive and Al-tolerant Cvsmentioning

confidence: 94%

Effect of aluminium on ion uptake and H⁺ release by maize

Calba

Jaillard²

1997

New Phytologist

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SUMMARYThe aim of this study was to quantify the long-term effects of Al in solution on mineral ion uptake and associated H^ release by the roots of maize cultivated in conditions compatible with field data. Two maize {Zea mays L.) cvs of differing sensitivity to Al were compared. The culture w^as conducted in hydroponic conditions for culture periods of 2-5 d in the presence of 0-30 /xm Al. Proton fluxes were localized along the roots using a videodensitometry method with bromocresol green on agarose gel.Aluminium reduced the uptake of anions, particularly NO3", whereas the uptake of K"^ and NH^^ was unaffected. These effects were accompanied by an increase in net H"^ release which was quantitatively comparable W'ith the reduction in NO3" uptake. The reduction in NO3" uptake and the concomitant increase in H"^ release increased with the quantity of Al accumulated in the roots, which was itself dependent on the concentration of Al in solution. The Al-sensitive cultivar bound more Al to its roots than the Al-tolerant one; the reduction in NO3ũ ptake and the increase in H"^ release were also greater in the Al-sensitive cv. Dye indicator videodensitometry show^ed that the increased H"^ release was general all along the roots.These results led us to specify the relation between the Al deposition in roots, the reduction in NO3" uptake and the stimulation in rhizosphere acidification by the plants. They show that, wdth maize, Al induces an inhibition in NO3" uptake and an increase in net H" release in a 1:1 ratio. These concomitant effects suggest that inhibition in NO3~/OH" exchange unmasks active H"^ excretion which is otherwise insensitive to Al. Both these effects are closely related to the Al content in roots expressed per unit root length.

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“…Per species 105 seedlings were selected and equally divided over seven 50-L containers filled with a solution containing (mM): K + 1.35; Ca 2+ 0.2; Mg 2+ 0.4; NH + 2.0; NOj-2.0; SOt-1.0; H2PO s 0.15; C1 0.4; FeEDTA 0.08 and additional micronutrients (Keltjens and van Ulden, 1987). To each container 0,5,10,15,20,25 or 30 mg L J Al was added as A1C13.…”

Section: Experiments 1 Effects Of Al On Growth Chemical Composition mentioning

confidence: 99%

“…Indirect effects on forest trees may result from dissolution of inorganic Ai at low soil pH (Hutchinson and Havas, 1980). A1 phytotoxicity has been shown with many different plant species (G6ransson and Eldhuset, 1987;Horst and G6ppel, 1986;Jarvis and Hatch, 1987;Keltjens and van Ulden, 1987;McCormick and Steiner, 1978). Although A1 enrichment in above-ground plant parts is usually low even at high external AI levels, aluminium can accumulate in and on roots to extremely high levels.…”

Section: Introductionmentioning

confidence: 96%

“…Recent findings (Keltjens and van Ulden, 1987;Taylor and Foy, 1985) that differences in AIsusceptibility might be associated with differential rhizosphere proton fluxes based on differences in NH~/NO3 uptake, were tested. Therefore, estimations of root proton efflux, NHg-/NO~ uptake, and in vivo nitrate reductase activity (NRA) were included.…”

Section: Introductionmentioning

confidence: 99%

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Effects of aluminium and mineral nutrition on growth and chemical composition of hydroponically grown seedlings of five different forest tree species

Keltjens

Loenen

1989

Plant Soil

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Forest die-back and impaired tree vitality have frequently been ascribed to Al-toxicity and Al-induced nutritional disorders due to increased acidification of forest soils. Therefore, in this experiment effects of A1 were studied on growth and nutrient uptake with seedlings of five different forest tree species. During growth in culture solutions with and without AI all five species proved to be very Al-tolerant, despite high accumulation of AI in roots. In the coniferous evergreens Douglas-fir and Scots pine shoot as well as root A1 concentrations were significantly higher than in the deciduous broad-leaved species oak and birch. Larch showed intermediate AI levels.In none of the five species did AI reduce nutrient concentrations or the Ca/A1 ratio to values below the critical level. Besides differences in AI accumulation, coniferous and broad-leaved species also differed with respect to uptake and assimilation of nitrogen. Due to extra NH~ uptake, oak and birch showed a much higher N uptake and higher NH~ preference than the coniferous species. Especially with oak this high NH4 + preference in combination with a low specific root surface area resulted in a high root proton efflux density. In comparison to both broad-leaved trees and Scots pine the NO3 reduction capacity of larch and Douglas-fir was extremely low. This may have important consequences for both species if grown in NO;--rich soils.

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Effects of Al on nitrogen (NH 4 + and NO 3 − ) uptake, nitrate reductase activity and proton release in two sorghum cultivars differing in Al tolerance

Cited by 64 publications

References 23 publications

Role of calcium in aluminium toxicity

Role of calcium in aluminium toxicity

Effect of aluminium on ion uptake and H⁺ release by maize

Effects of aluminium and mineral nutrition on growth and chemical composition of hydroponically grown seedlings of five different forest tree species

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Effects of Al on nitrogen (NH 4 + and NO 3 − ) uptake, nitrate reductase activity and proton release in two sorghum cultivars differing in Al tolerance

Cited by 64 publications

References 23 publications

Role of calcium in aluminium toxicity

Role of calcium in aluminium toxicity

Effect of aluminium on ion uptake and H+ release by maize

Effects of aluminium and mineral nutrition on growth and chemical composition of hydroponically grown seedlings of five different forest tree species

Contact Info

Product

Resources

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Effect of aluminium on ion uptake and H⁺ release by maize