Effects of Herbicides and Related Chemicals on Oxidation and Phosphorylation by Isolated Soybean Mitochondria.

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Abstract
Various concentrations of chemicals were added to Warburg flasks containing particles isolated from etiolated soybean hypocotyls. Of these chemicals, those generally considered to be growth-regulators were the more active inhibitors of oxidation. None of the chemicals stimulated oxygen uptake in the standard reaction mixture. However, a small increase (15 - 20%) was brought about by 2,4-dichlorophenoxy-acetic acid (2,4-D) when the inorganic P content of the reaction mixture was low. Since the inorganic P content also increased during the reaction, an uncoupling action of the 2,4-D was indicated. In vitro phos-phorylation appeared to be more sensitive to 2,4-D than was oxidation, as shown by a depression of the P:O ratio. Both participate oxidative and phosphorylative activities were increased by spraying the etiolated hypocotyls with 5 x 10-4M 2,4-D before isolation.