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The Effect of Oxycarboxin on Amino Acid Metabolism by Phaseolus vulgaris var. Pinto. Loy C. Newby, Department of Plant Pathology, University of Missouri, Columbia 65201, Present address of senior author: Ciba-Geigy Chemical Co., Ardsley, New York 10502; B. G. Tweedy, Department of Plant Pathology, University of Missouri, Columbia 65201. Phytopathology 63:686-688. Accepted for publication 13 December 1972. DOI: 10.1094/Phyto-63-686.

Amino acid metabolism was investigated in bean plants (Phaseolus vulgaris var. ‘Pinto’) treated with oxycarboxin. Plants were grown hydroponically in solutions containing 4.0 and 32 µg/ml of oxycarboxin. After treatment, discs were removed from the primary leaves and the free amino acids were extracted and quantitatively determined. The effect of oxycarboxin on incorporation of ¹⁴C-labeled CO₂ into the cation, anion and neutral metabolites was also investigated. The data obtained from these investigations though not conclusive suggest that biochemical alteration of the host is not a primary mode of action by oxycarboxin for controlling bean rust caused by Uromyces phaseoli.