Ljv ' Ne and Levine Respiration and Oxidative Phosphorylation of Nacl - Treated Leaves

Summetlary. The effect of sodium chloride added to root medium of pea seedlings on respiratory activity of tissue segments and on isolated mitochondria was studied. Salinization enhances the respiration of leaves about one-third on a fresh weight, dry weight or protein basis. Roots and stems show only 10 to 15 % respiratory stimuilation. The onset of respiratory increase in leaves rouighly parallels the increase in NaCl content and the decrease in growth rate. At a later stage the elevated respiration is appareint in treated plants even though the concentration of NaCIl reaches a plateaut and osmotic adjustment is being reached. Stimtulation of respiration was fotund in both etiolated and green plants. Experiments with DNP show that simple uincoupling by salt is not involved; the respiratory increase in control and treated tissule is proportionally the same. In accordance with increased respiration rates observed in vivo, mitochondria from salt-treated plants show higher rates of oxygen uptake oln several substrates. The effect of NaCl added during growth is long term and is distinct from the effect of NaCl added to mitochondria isolated from control plants. Since P/O ratios are not affected by NaCl, the potential for oxidative phosphorylation in salt-affected tissuie appears to iincrease. It is postuilated that this increase may lead to changes in ADP and ATP content, andl in tuirn, affect regulation of metabolic pathways.