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Physiology and Biochemistry

Purification and Partial Characterization of Host-Specific Toxins Produced by Periconia circinata. T. J. Wolpert, Research assistant, Science and Education Administration, U.S. Department of Agriculture, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907; L. D. Dunkle, research plant pathologist, Science and Education Administration, U.S. Department of Agriculture, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907. Phytopathology 70:872-876. Accepted for publication 1 March 1980. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/Phyto-70-872.

Host-specific toxins isolated from culture filtrates of Periconia circinata inhibited root growth of the susceptible sorghum genotype by 50% at 1 ng/ml and had no effect on root growth of the near-isogenic resistant genotype at 2 μg/ml. Purity of the isolated products was assessed by thin-layer chromatography (TLC), thin-layer electrophoresis (TLE), and high-performance liquid chromatography (HPLC) of the toxins or their dansyl derivatives. Two toxic substances were separated by preparative TLC; each contained only aspartic acid and two components with properties of polyamines. HPLC resolved each of those toxic fractions into two compounds, a biologically active one and an inactive one. In addition to aspartic acid, both active compounds contained the same polyamine, and both inactive compounds contained another electrophoretically distinct polyamine. The Periconia toxins are low-molecular-weight, acidic compounds containing multiple residues of aspartic acid and one or more residues of a polyamine, which is responsible for ninhydrin reactivity and apparently responsible for selective biological activity.