Potassium and Rubidium Interaction in Their Absorption by Bean Leaf Slices

Jacoby, B.; Nissen, P.

doi:10.1111/j.1399-3054.1977.tb01491.x

Cited by 11 publications

(2 citation statements)

References 17 publications

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“…Moreover, the varying discrimination between K"^ and Rb"*^ cannot affect what appears to be the main conclusions of our work, those about an influence of RH on efflux from the cytoplasm and vacuole of the root cells. A discrimination between K and Rb varying with concentration of K"*" was noted and discussed by Jacoby and Nissen (1977).…”

Section: Discussionmentioning

confidence: 99%

Effects of ionic strength and relative humidity on the efflux of K⁺ (⁸⁶Rb) and Ca²⁺ (⁴⁵Ca) from roots of intact seedlings of cucumber, oat and wheat

Jensen

Kylin

1980

Physiologia Plantarum

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Spring wheat (Triticum aestivum L. cv. Svenno), oat (Avena sativa L. cv. Brighton) and glasshouse cucumber (Cucumis sativus L. cv. Bestseller Fl) were cultured for a week after germination on complete nutrient solutions of three different dilutions (1, 25 and 50% of the full strength medium). K-'(*''Rb) and "'Ca were present during the whole culture period. Relative humidity (RH) was 50% except during the last day, when half the material was transferred to 90% RH. Efflux of labelled ions was then followed during eight hours on unlabelled solutions of the same composition as before, and at both 50% and 90% RH in the atmosphere. -Uptake of K"^(*''Rb) during growth tended to be saturated in the 25% medium. Contrariwise, the level of Ca^"^ in the roots increased continuously with strength of the medium. At low concentrations cucumber roots were higher in Ca^"^ than roots of oat or wheat, whereas all three species showed similar levels of Ca^"^ in 50% medium. -At the lowest ionic strength, smooth efflux curves were obtained that could be resolved according to the three-compartment theory. At higher ionic strength, irregularities were observed, and more for Ca'' ' than for K*; but for practical purposes compartment analysis with the same time constants could be applied as for the lowest concentration. -Discrimination between K"^ and Rb"^ differed between the roots, but not much between the shoots of different species. The roots of oat and wheat took up Rb"^ preferentially over K "^ in the 25% and 50% media; whereas K"*" was preferred over Rb^'^or little discrimination made in 1 % medium and for cucumber. The shoots generally showed less discrimination than the roots. The main variability in discrimination between K"^ and Rb"^ thus appears to be localized in the tonoplasts of the roots cells. -Low RH around the shoots increased efflux of K'^(**'Rb) from the cytoplasm and vacuoles of the root cells as compared to the efflux at high RH. DNP (2,4-dinitrophenol) in the medium had the same effect as high RH around the shoots. The signal system that must exist between shoots and roots is discussed as a response to "drought" conditions. In relation to investigations of others, it is assumed that the effect of DNP may indicate that part of the chain between roots and shoots consists of metabolically influenced sites, whose output is influenced by the rate of water transport.

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Section: Discussionmentioning

confidence: 99%

Effects of ionic strength and relative humidity on the efflux of K⁺ (⁸⁶Rb) and Ca²⁺ (⁴⁵Ca) from roots of intact seedlings of cucumber, oat and wheat

Jensen

Kylin

1980

Physiologia Plantarum

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“…Justification of the widespread use of 86 Rb + as a potassium analogue stems from several reports suggesting that, at least in some cases, there is little discrimination between the two ions (Kochian and Lucas 1982, Läuchli and Epstein 1970, Polley and Hopkins 1979). However, numerous other studies have shown that, on the contrary, 86 Rb + is a poor tracer for K + in higher plant systems (Behl and Jeschke 1982, Cline and Hungate 1960, de Agazio et al 1983, Jacoby 1975, Jacoby and Nissen 1977, Kannan and Ramani 1973, Maas and Leggett 1968, Marschner and Schimanski 1968, Schachtman et al 1992); substantial discrimination between the two elements has also been observed in Nitellopsis (MacRobbie and Dainty 1958), Chlamydomonas (Malhotra and Glass 1995, Polley and Doctor 1985), Chara (Keifer and Spanswick 1978), Ulva and Chaetomorpha (West and Pitman 1967), as well as in Escherichia coli (Rhoads et al 1977). Moreover, the discrimination between these elements is not uniform across experimental conditions.…”

Section: Hats and Lats: The Two‐mechanism Modelmentioning

confidence: 99%

Cellular mechanisms of potassium transport in plants

Britto,

Kronzucker

2008

Physiologia Plantarum

209

139

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Potassium (K(+)) is the most abundant ion in the plant cell and is required for a wide array of functions, ranging from the maintenance of electrical potential gradients across cell membranes, to the generation of turgor, to the activation of numerous enzymes. The majority of these functions depend more or less directly upon the activities and regulation of membrane-bound K(+) transport proteins, operating over a wide range of K(+) concentrations. Here, we review the physiological aspects of potassium transport systems in the plasma membrane, re-examining fundamental problems in the field such as the distinctions between high- and low-affinity transport systems, the interactions between K(+) and other ions such as NH(4)(+) and Na(+), the regulation of cellular K(+) pools, the generation of electrical potentials and the problems involved in measurement of unidirectional K(+) fluxes. We place these discussions in the context of recent discoveries in the molecular biology of K(+) acquisition and produce an overview of gene families encoding K(+) transporters.

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Electrogenic pump activity in red beet: Its relation to ATP levels and to cation influx

Mercier

Poole

1980

J. Membrain Biol.

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Summary. In storage tissue of Beta vulgaris L., carbonyl cyanide m-chlorophenylhydrazone or cyanide+salicylhydroxamic acid reduce cell electropotentials from about -200 to below -100 inV. The relationship between potential and cellular ATP level is examined during treatment with different concentrations of inhibitors. At low ATP levels the potential rises sharply with increases in ATP, but above an ATP level of approximately 50% of the uninhibited level the potential changes very little with ATP concentration. A plot of membrane potential vs. 86Rb+ influx or of potential vs. net K + uptake indicates that as the level of inhibition is decreased, the potential tends to reach a limit while cation influx and net uptake continue to increase. Resistance measurements, although subject to difficulties of interpretation, indicate no change in conductance with potential, ion flux, or ATP level. Thus the membrane potential should directly reflect electrogenic pump activity, attributed to active uncoupled H + efflux. K + uptake can occur against its electrochemical gradient and is attributed to a coupled K + influx/H + efflux pump. The results show that the electrogenic pump activity is independent of the K+/H + exchange rate. Thus electrogenic H + efflux and K+/H + exchange may represent different transport systems, or different modes of operation of a single pump with variable stoichiometry.Electrogenic pumps, i.e., primary transport processes which contribute directly to the membrane potential, are a conspicuous feature of plant cells [26]. In most cases it appears to be the efflux of H § which gives rise to an energy-dependent hyperpolarization. Net * Current address: Department of Biology, University of Calgary, Calgary, Alberta T2N 1N4, Canada.H + efflux is usually associated with the accumulation of K § or other cations, but the link between these ion movements is not yet clear. Slices of storage tissue of red beet (Beta vulgaris L.) appear to be a favorable material for investigation of the relation between these transport processes [25] since a large and prolonged efflux of H+, an equivalent influx of K +, and a conspicuous hyperpolarization are all evoked by raising the external pH from about pH 6.5 to pH7.5. Other ion movements such as active (K + +C1-) influx are not sensitive to pH and are much smaller than K+/H + exchange at high pH. In the present study, membrane potentials in beet cells at high pH are investigated in relation to changes in ATP level brought about by metabolic inhibitors, especially cyanide. In addition, membrane potentials are compared with cation influx over various levels of metabolic inhibition, and the results are interpreted in terms of possible schemes of energy coupling for the electrogenic pump and for the accumulation of cations. Materials and Methods Tissue Preparation

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Potassium and Rubidium Interaction in Their Absorption by Bean Leaf Slices

Cited by 11 publications

References 17 publications

Effects of ionic strength and relative humidity on the efflux of K⁺ (⁸⁶Rb) and Ca²⁺ (⁴⁵Ca) from roots of intact seedlings of cucumber, oat and wheat

Effects of ionic strength and relative humidity on the efflux of K⁺ (⁸⁶Rb) and Ca²⁺ (⁴⁵Ca) from roots of intact seedlings of cucumber, oat and wheat

Cellular mechanisms of potassium transport in plants

Electrogenic pump activity in red beet: Its relation to ATP levels and to cation influx

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Potassium and Rubidium Interaction in Their Absorption by Bean Leaf Slices

Cited by 11 publications

References 17 publications

Effects of ionic strength and relative humidity on the efflux of K+ (86Rb) and Ca2+ (45Ca) from roots of intact seedlings of cucumber, oat and wheat

Effects of ionic strength and relative humidity on the efflux of K+ (86Rb) and Ca2+ (45Ca) from roots of intact seedlings of cucumber, oat and wheat

Cellular mechanisms of potassium transport in plants

Electrogenic pump activity in red beet: Its relation to ATP levels and to cation influx

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Effects of ionic strength and relative humidity on the efflux of K⁺ (⁸⁶Rb) and Ca²⁺ (⁴⁵Ca) from roots of intact seedlings of cucumber, oat and wheat

Effects of ionic strength and relative humidity on the efflux of K⁺ (⁸⁶Rb) and Ca²⁺ (⁴⁵Ca) from roots of intact seedlings of cucumber, oat and wheat