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Physiology and Biochemistry

Production and Some Characteristics of Host-Specific Toxin(s) Produced by Several Isolates of Helminthosporium maydis race T. G. A. Payne, Department of Plant Pathology, Cornell University, Ithaca, NY 14853, Present address of senior author: Laboratory of Agricultural Biochemistry, University of Nebraska, Lincoln, NE 68583; O. C. Yoder, Department of Plant Pathology, Cornell University, Ithaca, NY 14853. Phytopathology 68:707-714. Accepted for publication 18 November 1977. Copyright 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-707.

Isolates of Helminthosporim maydis race T from several geographical locations were compared for ability to produce in culture a toxin that is selective against corn containing Texas male-sterile cytoplasm. The isolates did not differ significantly in virulence on corn, growth rate in culture, or rate at which toxin was produced in culture, but small differences were detected in quantity of toxin produced in light versus dark conditions. Toxin preparations were tested for stability at several pH values and were analyzed in several chromatographic systems; there were no apparent differences among preparations from the isolates. There were indications that more than one host-specific toxin could be found in partially purified preparations, but there was no evidence for differences in biological activity or in host-specific activity among different fractions. The instability of these materials in chromatographic systems did not permit reproducible qualitative analyses.

Additional keywords: southern corn leaf blight, Zea mays.