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Postharvest Pathology and Mycotoxins

Inhibition of ³H-Leucine Incorporation by Trichothecene Mycotoxins in Maize and Wheat Tissue. W. L. Casale, Graduate research assistant, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824; L. P. Hart, Associate professor, Department of Botany and Plant Pathology, Michigan State University, East Lansing 48824. Phytopathology 78:1673-1677. Accepted for publication 14 July 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-1673.

The trichothecenes, deoxynivalenol (DON, vomitoxin) and T-2 toxin, inhibited ³H-leucine incorporation into acetone:ethanol insoluble material by maize and wheat tissue (leaf disks and kernel sections). These compounds are known to inhibit protein synthesis in animals and yeast. The toxin concentrations that gave ID₅₀ (50% reduction) for ³H-leucine incorporation by several maize varieties were 0.9 μM T-2 toxin and 9–22 μM DON. ID₅₀ values for wheat were 0.26 μM T-2 toxin and 4.5 μM DON. T-2 toxin gave near-maximum inhibition in leaf tissue within 5 min after exposure to the toxin. T-2 toxin or its effects on ³H-leucine incorporation persisted at least 120 min after removal of leaf disks from toxin solutions. Sensitivity to DON was not correlated with susceptibility to ear rot by a DON-producing strain of Gibberella zeae (anamorph = Fusarium graminearum) for six maize lines with a range of disease reactions from highly susceptible to highly resistant. However, the ID₅₀ for one moderately resistant line (A509) was 2.3 times greater than the ID₅₀ of the most susceptible line (B79). ³H-Leucine incorporation by wheat and maize was inhibited by DON and T-2 toxin at concentrations occurring in naturally infected tissue, suggesting the need for further evaluation of these compounds as plant disease determinants.