Impairment of Respiration, Ion Accumulation, and Ion Retention in Root Tissue Treated with Ribonuclease and Ethylenediamine Tetraacetic Acid

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Abstract
Treatment of soybean or corn root tips with ribonuclease, ethylenediamine tetraacetic acid or high concentrations of KCl impaired respiration after 1-3 hours. Concurrently, cold-acid soluble nucleotides were lost, partly to the medium; polynucleotides began to degrade. The lowered respiration was related to loss of mitochondrial activity. Cell membranes lost their semi-permeability. The expanding root zone showed the greatest loss of soluble nucleotides and polynucleotides, respiration and K accumulation when treated with EDTA. This zone had the highest RNase activity. Phosphate accumulation and ion retention were most impaired in the meristematic and early cell expansion zones. It is believed that RNA in membranes is implicated in ion accumulation, solute retention and oxidative phosphorylation. It is thought that divalent ions normally protect this RNA from degradation by endogenous enzymes, and that substitution of monovalent ions for divalent ions leads to the degradation of membranous RNA and the loss of physiological and biochemical functions. Normal metabolism of RNA could be governed by K/Ca + Mg ratios. Salt respiration may result from partial degradation of mitochondrial RNA.