The Role of Calcium in the Absorption of Anions and Cations by Excised Barley Roots

Hooymans, J. J. M.

doi:10.1111/j.1438-8677.1964.tb00171.x

Cited by 65 publications

(39 citation statements)

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“…The increased Cl uptake by the roots from KCI solutions as the CaSO4 concentration was increased is in accord with the effect of CaSO4 on Br uptake by excised barley roots from KBr solutions observed by Viets (20) and in several other studies (3,7,17). It is likely that the greater increase in K uptake from KCI than from K2SO4 solutions when CaSO4 was added is the result of the increased Cl uptake.…”

Section: Discussionsupporting

confidence: 75%

“…Uptake of bromide, chloride and sulfate by excised barley roots is also increased by addition of calcium to the culture solution (3,7,12,20). The presence of calcium and of some other polyvalent cations in culture solutions also influences the ability of roots of barley and many other plants to accumulate potassium in preference to sodium from solutions containing both ions (5, 9).…”

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confidence: 98%

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Role of the Accompanying Anion in the Effect of Calcium Salts on Potassium Uptake by Excised Barley Roots

1969

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(7,14,20,21). Uptake of bromide, chloride and sulfate by excised barley roots is also increased by addition of calcium to the culture solution (3,7,12,20). The presence of calcium and of some other polyvalent cations in culture solutions also influences the ability of roots of barley and many other plants to accumulate potassium in preference to sodium from solutions containing both ions (5, 9).Over the concentration range of about 0.5 to 50 mm, uptake of monovalent cations may be influenced by the accompanying anion (6). When K uptake is limited by anion uptake, addition to culture solutions of calcium salts of anions such as chloride that are rapidly accumulated by excised barley roots may, in addition to any direct effect of calcium ions, stimulate potassium uptake as a result of increased anion uptake. Indeed, Elzam and Hodiges (4) observed that although the addition of CaCl2 to culture solutions increased potassium uptake by excised barley roots, the addition of CaSO4 had no effect. Also, Pitman (17) has shown that slices of beet 1 Present Address: Department of Agricultural Cheniistry, Hokkaido University, Kita-9, Sapporo, Japan. root tissue accumulate more chloride from solutions containing both potassium and calcium than from KCl solutions at the same chloride concentration. Pitman (17) concluded that chloride uptake limited potassium uptake by the beet root tissue and that calcium acted to increase chloride uptake and consequently potassium uptake. The effects of calcium salts on accumulation of potassium and other ions however, are usually attributed to a direct effect of calcium ions without consideration of possible influences of the nature or concentration, of the accompanying anion. The purpose of this study was to attempt to separate the effeicts of calcium ions and the accompanying anion on potassium uptake, and the selectivity for potassium by excised barley roots. Materials and MethodsExcised barley IHordeum vulgare L., var. Erie) roots were grown essentially as described by Jacobson et al. (9). For each experiment, 50 grams of seed were treated with 75 ml of 10 % '(v/v) HO02 for 10 min. After discarding the H202 solution, the seeds were rinsed with distilled water and then soaked for 24 hr in 1500 ml of aerated distilled water. The seeds were then placed on cheesecloth supported by a nylon screen and covered with another nylon screen and cheesecloth. The screen suipporting the seeds was suspended over 8 PLANT PHYSIOLOGYThe seedlings were grown in a dark chamber at 250. After 2 days the screen and cheesecloth covering the seedlings were removed. After the plants had grown for 3 days, the nutrient solution was replaced with fresh nutrient solution. On the fifth day the nutrient solution was replaced with distilled water and 24 hr later the roots were excised jus't below the screen. The excised roots were rinsed several times with flowing distilled water and placed in 4 liters of aerated distilled water for 1 hr before use in an experiment.The experiments were conducted at 250 using a ratio of ...

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confidence: 75%

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Role of the Accompanying Anion in the Effect of Calcium Salts on Potassium Uptake by Excised Barley Roots

1969

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“…1) Calcium ions in the medium play a crtucial, indeed an indispensable, role in selective ion transport by plant tisstues. This is so for absorption of alkali cations (4,5,14,16,18,19,22,23), halides (1,3,4,16,19,23), and for other ions as well (25). The role of calciuim in preveniting or reversing dlamage to the cellullar transport mechan,isms catused by sodiuim is partictularly striking (4,5).…”

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Sodium Absorption by Barley Roots: Role of the Dual Mechanisms of Alkali Cation Transport

1967

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Summatnry. Radioactively labeled Na+ absorbed by barley roots wvas sequiesteredl in an intracelluilar compartmenit or compartmeints ("inner" spaces) bettween the concentrationi of Na. and the rate of its absorptioni. The mechanism of Na' absorption operatiing over this range of concenitrationls, mechanism 1 of alklali catioin transport, is severely inhibited in the presenice of Ca2' and virtually rendered inoperative for Na+ transport by the combined presence of Ca2+ and K+. The iechanism is eqtually effective in Na+ transport whether Cl-or F-is the anion, but is somewhat inhibited when the anion is S042-.Over the high range of concenitrations, 0.5 to 50 mm Na+, a second, low-affinity mechanism of Na+ absorption comes into play. In the presence of. Ca2+ and K+, this mechainism 2 is the only onie to transport N,Ia+ effectively, silnce \a+ absorption via mechanism 1 is virtually abolished tinder these conditions. Anaerobic conditions, low temperatture, and the uncotupler, 2, 4-dinitrophenol, inhibit Nad absorption both at low and high Na+ concentrations.Sodium is the predomiiinant cation in the world's ocealns and(I the preponderanit soltible cation in many of the soils of those very large land areas lying in the ari(l and( semi-aril regions of the earth. However, its absorption by planits and plant tissnies has been stuldie(d muich less than that of potassiuim, the only alkali metal knowin to be uiniversally esselntial for all higher plants (7). In the present work, colncepts and findings gainied primarilv from experimelnts on the absorption of potassium (and rulbidiuim) have been applied to the stuidy of soditum absorption by excised barley roots.The prevriolus conclusions referre(d to are 2-fold. 1) Calcium ions in the medium play a crtucial, indeed an indispensable, role in selective ion transport by plant tisstues. This is so for absorption of

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“…Bange and ShaminieDellaert (1) reported that steady state Rb+ absorption by barley roots was insensitive to the presence of Ca2+. Hooymans (10) reported that Ca2+ inhibited K+ absorption by barley roots from 0.01 mM K+ and enhanced absorption from 0.2 mm K+.…”

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“…Simultaneous experiments were conducted with sorption of highly hydrated ions such as Li+ and Na+ (1,7,10,11,18,19) and enhances absorption of less hydrated ions such as K+ or Rb+ (4,11,12,14,15,19 (12) reported that Ca2+ enhanced K+ absorption from 1 mm KCI by maize roots and depressed K+ absorption by soybean roots. Bange and ShaminieDellaert (1) reported that steady state Rb+ absorption by barley roots was insensitive to the presence of Ca2+.…”

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An Anomaly in Potassium Accumulation by Barley Roots

Hiatt

1970

Plant Physiol.

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When excised barley roots were incubated for 2 to 24 hr in KCI solutions of 0.01 to 0.1 mM concentration, the K+ accumulation curve exhibited an anomalous appearance (8, 9). As KC1 concentration was increased from nil to 0.04 mm, K+ uptake increased as expected. However, further increase in KCI concentration to 0.06 mm resulted in decreased absorption of K+. This accumulation peak always occurred at approximately 0.04 mm and was not shifted appreciably by changes in Na+ concentration or species of counteranion.The literature is replete with examples of absorption against concentration curves which do not exhibit this phenomenon (2,3,5,6,16). Generally the absorption curves for salt concentrations less than 1 mm are reported to be hyperbolic with near maximal rates of the low concentration mechanism observed at approxiniately 0.2 mm. The investigations cited above were concerned primarily with absorption kinetics and were limited to absorption periods of 10 min to 3 hr. In most kinetic studies of K absorption, K uptake is followed by the use of 86Rb as a tracer.This (8,9). Figure 1 shows the results of a 0.1 mm KCl-NaCl replacement series experiment in which CaS04 was omitted. Accumulation curves for high K+-low Na+ solutions were not changed markedly by the omission of Ca2+ (compare with Fig. 1 of Ref. 9); however, omission of Ca2+ from low K+-high Na+ solutions strikingly reduced the apparent preference for K+ over Na+. In the absence of Ca2+ the peak of the K+ accumulation curve occurred at 0.01 mM, and the roots actually lost K to solutions containing 0.02 mm K+ and 0.08 mm Na+. Figure 2 shows the effect of Ca2+ concentration on K+ accumulation in 24 hr from KCI solutions varied in concentration from 0.005 to 0.2 mz. In the absence of Ca2+, K+ accumulation showed a peak at the lowest KCI concentration used (0.005 mM) and a trough at 0.015 mm. With KCl concentrations greater than 0.02 mm the KCl accumulation curve was hyperbolic. The peak in the K+ accumulation curve was shifted to higher KCl concentrations as the solution Ca2+ concentration was increased. Varying the Ca2+ concentration from 0.02 to 1.0 mm had little effect on K+ accumulation from KCI solutions greater than 0.1 mm.Since the studies of Viets (17) on the stimulating effect of calcium on ion uptake, considerable attention has been given to the relationship of Ca2+ to ion uptake. The results have not always been consistent, with both reported stimulation and inhibition of K+ uptake by Ca2+, and the foregoing results might partially explain these observations. Part of the data from Figure 2 is plotted in a different manner in Figure 3. In Figure 3

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The Role of Calcium in the Absorption of Anions and Cations by Excised Barley Roots

Cited by 65 publications

References 31 publications

Role of the Accompanying Anion in the Effect of Calcium Salts on Potassium Uptake by Excised Barley Roots

Role of the Accompanying Anion in the Effect of Calcium Salts on Potassium Uptake by Excised Barley Roots

Sodium Absorption by Barley Roots: Role of the Dual Mechanisms of Alkali Cation Transport

An Anomaly in Potassium Accumulation by Barley Roots

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