Organic Acid Metabolism and Ion Absorption in Roots

Jacobson, Louis; Ordin, Lawrence

doi:10.1104/pp.29.1.70

Cited by 113 publications

(55 citation statements)

References 8 publications

(9 reference statements)

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“…By contrast, in agreement with a welter of studies with vacuolated roots (10,12,17,18,43), K&SO, a salt with a poorly absorbable anion, evoked pronounced organic acid synthesis compared with KCl. Since we have taken system 2 to represent tonoplast transport (21), we have been prone to emphasize the role of the tonoplast in organic acid synthesis.…”

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“…Also, in contrast to root tips, the amount of malate in intact roots did not change when net synthesis stopped after the 1st hr in CaSO4, but rather remained almost constant for several hours. These (10,17,18,43), the relative excess of absorbed potassium over the increase in malate content decreases with incubation time (Fig. 3) Figure 3.…”

Section: Materiais and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…It has been amply established that the organic acid synthesis which accompanies excess cation absorption is the result of dark CO, fixation (3,14,17,18,43), and it remains to determine the manner in which one or more of the multiplicity of carboxylating enzyme sys-'Supported by Contract tems (11,40,47) is influenced by the act of preferential cation uptake, and the reason the response bears such a provocative quantitative relationship to the causative event.…”

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confidence: 99%

“…On the one hand, it has been suggested by Burstrom (3), and subsequently by others, that additional organic acid synthesis is directly evoked by what is in effect the titration of cytoplasmic organic acid, specifically, the conversion of malic acid to malate. The titration may be accomplished by the exchange of cytoplasmic H+ for external cation (15,17,18,43), or by the metabolism of cytoplasmic NO,-, with consequent NH. formation (3).…”

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Bicarbonate Fixation and Malate Compartmentation in Relation to Salt-induced Stoichiometric Synthesis of Organic Acid

Jacoby

Laties

1971

Plant Physiol.

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The relationship of malate synthesis to K absorption from solutions of K2SO4 and KHCO3 was compared in nonvacuolate barley (Hordeum vulgare) root tips and whole excised roots. The comparison has permitted separation of the process which evokes organic acid synthesis from that which leads to stoichiometry between net acid equivalents formed and excess K+ absorbed from K2SO4, on the one hand, and total K+ absorbed from KHCOs, on the other. Both in tips and in roots K+ uptake from 20 mN salt solution exceeds malate synthesis in the first hour. In vacuolate roots the expected stoichiometry is achieved with time. When root tips are transferred to dilute CaSO4, malate is rapidly metabolized, and K+ is lost to the solution. By contrast, in excised whole roots the malate level remains unchanged, the salt-induced organic acid presumably being retained in the vacuole. In excised roots malonate leads to a marked drop in malate levels in untreated roots as well as in roots which have experienced salt-induced net malate synthesis. In consequence, it is contended that malonate makes available normally sequestered vacuolar malate.The general hypothesis is offered that the bicarbonate level of the cytoplasm controls organic acid synthesis by phosphoenolpyruvate carboxylase, and that the cytoplasmic bicarbonate level is raised either by exchange of cytoplasmic HI for external cation, or by bicarbonate absorption directly. Stoichiometry, in turn, is achieved by the accumulation in the vacuole of the double salt of malate.The time-honored observation linking organic acid synthesis in plant tissue to preferential cation uptake is still attended by the primordial questions of what elicits synthesis, and why there is a stoichiometric relationship between the equivalents of acid produced and the excess of cation absorbed over the counter anion taken up. It has been amply established that the organic acid synthesis which accompanies excess cation absorption is the result of dark CO, fixation (3,14,17,18,43), and it remains to determine the manner in which one or more of the multiplicity of carboxylating enzyme sys-

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Section: Materiais and Methodsmentioning

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Section: Introductionmentioning

confidence: 99%

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Bicarbonate Fixation and Malate Compartmentation in Relation to Salt-induced Stoichiometric Synthesis of Organic Acid

Jacoby

Laties

1971

Plant Physiol.

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Effects of Chlorides on the Metabolism of Pineapple Plants

Sideris¹,

Young²

1954

American J of Botany

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Osmotic Adjustment of Plants to Saline Media. Ii. Dynamic Phase

Bernstein

1963

American J of Botany

108

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A B S T RAe'!' 13ERXSTI';Il'i, LI,;oN. (D. S. Salinity Lab., Riverside, Calif.) Osmotie adjustment of plants to saline media. II. Dynamic phase. Amer. Jour. Bot. 50(4): 360-370. Illus. HJ63.-The time-course of osmotic adjustment in bean and pepper plants to increased salinity of the medium was determined by periodic sampling of plants following salt additions to the medium. Bean plants adjusted to increases of 1 atrn or within a day, the adjustment in roots occurring primarily at night following salt addition at 6 I'M, whereas leaves and stems made most of their adjustment in the daytime.Pepper plants did not adjust completely to 1.5 atrn Ne.Cl additions in 48 hr, but or increased by about the same amount in both species (0.5-1.0 atm per day). Diurnal fluctuations in OP of leaves and stems of both species and in roots of pepper were matched by parallel fluctuations in K concentrations. Added N aCl caused increased concentrations of K in leaves and stems which were more or less replaced by more slowly absorbed ions, Ca and Mg in bean leaves and Na in bean stems. Other salts produced comparable immediate effects on K level, but K was replaced more rapidly if the cation added was readily accumulated by the bean (Ca). In roots, Na uptake predominated if Na salts were added but K uptake was important on the CaCI, treatment. The K effects suggest II passive distribution of K between the ceIl lind the medium.

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Organic Acid Metabolism and Ion Absorption in Roots

Cited by 113 publications

References 8 publications

Bicarbonate Fixation and Malate Compartmentation in Relation to Salt-induced Stoichiometric Synthesis of Organic Acid

Bicarbonate Fixation and Malate Compartmentation in Relation to Salt-induced Stoichiometric Synthesis of Organic Acid

Effects of Chlorides on the Metabolism of Pineapple Plants

Osmotic Adjustment of Plants to Saline Media. Ii. Dynamic Phase

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