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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 922 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.