Effects of Pargyline on Mitochondrial Amine Oxidase Activity, Indoleacetic Acid Synthesis and Growth of Crown-Gall Tumor Callus

Vinca rosea L. crown-gall tumor callus tissue cultures treated with N-benzyl-N methyl propargylamine (pargyline) exhibited a decrease in the level of endogenous indoleacetic acid from 0.42 μg/mg of protein to less than 0.30 μg/mg of protein. A simultaneous decrease in the specific activity of mitochondrial amine oxidase from 3000 units to less than 250 units at 1.0 μM, 0.01 mM, 0.1 mM and 1.0 mM pargyline, suggested a relationship between amine oxidase function and indoleacetic acid synthesis. Tryptamine incorporation into indoleacetic acid was also decreased at these concentrations. Pargyline inhibited tumor callus growth significantly (based on fresh weight measurements) at the highest concentration, 1.0mM. These data support the hypothesis of a coordinate metabolic system linking mitochondrial amine oxidase activity and indole acetic acid synthesis. Inhibitory action of pargyline on the enzyme is reflected in reduced indoleacetic acid levels and, ultimately, in reduced callus growth rates.