Metabolism of Non-Volatile Organic Acids in Excised Barley Roots as Related to Cation-Anion Balance during Salt Accumulation

Ulrich, Albert

doi:10.2307/2436998

Cited by 94 publications

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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.…”

supporting

confidence: 86%

“…However, since salt-induced net malate synthesis proved immeasurably low under such conditions, we turned our attention to root tips where, because of the absence of vacuoles, high salt concentrations could be used without ambiguity arising from the influence of tonoplast transport on organic acid synthesis. The enhancement of K+ uptake by bicarbonate is accompanied by a marked increase in organic acids (14,43). In consequence we investigated the effect of KHCO.…”

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.…”

mentioning

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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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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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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confidence: 86%

Section: Materiais and Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

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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Studies on the adaptation of selected species of the family Gramineae A. JUSS. to salinization

et al. 1992

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The effect of salinity has been examined on osmolality, electric conductivity and pH values of cell‐sap and mineral composition (macro and micro nutrient elements) of barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), and maize (Zea mays L.). The results show that with the exception of potassium and nitrogen contents the levels of most inorganic macro nutrient elements (sodium, calcium, magnesium, phosphorus) and micro nutrient elements (iron, boron, zinc, manganese, copper and chloride) increased with increase salinity concentrations. This was true also for osmolality and electric conductivity but not pH.

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The Influence of Some Respiratory Inhibitors and Intermediates on Respiration and Salt Accumulation of Excised Barley Roots

Machlis

1944

American J of Botany

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Metabolism of Non-Volatile Organic Acids in Excised Barley Roots as Related to Cation-Anion Balance during Salt Accumulation

Cited by 94 publications

References 0 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

Studies on the adaptation of selected species of the family Gramineae A. JUSS. to salinization

The Influence of Some Respiratory Inhibitors and Intermediates on Respiration and Salt Accumulation of Excised Barley Roots

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