Inhibition of succinate oxidation by the herbicide UKJ72J

The inhibitory activity of the herbicide UKJ72J on succinate oxidation in mitochondria from various plant species was studied. In monocotyledons (Gramineae: wheat, oat, maize; Liliaceae: onion, leek) succinate oxidation was affected only at high concentrations. Among dicotyledons widely differing sensitivities were found: in Solanaceae (tomato, potato, tobacco), Leguminosae (mung bean, soybean) and Compositae (sunflower) I₅₀ concentrations for UKJ72J inhibition were below 55 μM. In Cruciferae (turnip, cauliflowers Chenopodiaceae (lambsquarter, beetroot) and Compositae (endive) I₅₀ were between 100 and 250 μM, whereas in Rosaceae (apple, pear) and Umbelliferae (carrot, fennel) I₅₀ were near (apple) or higher than 500 μM. No correlation could be found between the sensitivity to UKJ72J of mitochondrial succinate oxidation in these families and their location in the presently accepted flowering plant classification.