Loss of Organic Acids, Amino Acids, K, and Cl from Barley Roots Treated Anaerobically and with Metabolic Inhibitors

Abstract

Excised roots of barley (Hordeum vulgare, var. Campana) lost organic acids, amino acids, K⁺, and Cl⁻ within 15 minutes after initiation of anaerobic treatment or treatment with NaCN and 2,4-dinitrophenol. Initial loss of organic acids when roots were placed under N₂ is attributed to a decarboxylation reaction, possibly catalyzed by phosphoenolpyruvate carboxykinase. Organic and amino acids began to leak from the roots to the bathing medium after 1 to 2 hours under N₂, indicating injury to cell membranes. During the first hour of anaerobic treatment, K⁺ loss from low-salt roots was equivalent to organic acid loss. Potassium loss from roots containing high levels of KCl was approximately equal to organic acid plus amino acid loss; and Cl⁻ loss was approximately equal to amino acid loss. It is postulated that, within cells, organic acids may electrostatically bind an equivalent quantity of cations and that amino acids may bind an equivalent quantity of both cations and anions.