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Physiology and Biochemistry

Production of Zinniol by Alternaria tagetica and its Phytotoxic Effect on Tagetes erecta. P. J. Cotty, Department of Plant Pathology, University of Arizona, Tucson 85721; I. J. Misaghi(2), and R. B. Hine(3). (2)(3)Department of Plant Pathology, University of Arizona, Tucson 85721. Phytopathology 73:1326-1328. Accepted for publication 13 April 1983. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-1326.

Alternaria tagetica, the causal agent of stem, leaf, and flower blight of marigold, is capable of producing phytotoxins in vitro. One of the toxins was identified as zinniol by comparing it with synthetic zinniol in: bioassays; thin-layer and gas chromatography; staining properties; ultraviolet and mass spectrometry, and nuclear magnetic resonance spectroscopy. The identity of the other toxin(s) has not been established. Symptoms similar to those caused by infection developed on detached marigold leaves treated with either of the toxins or synthetic zinniol. The toxins are not host selective and are capable of causing injury to zinnia, cotton, okra, corn, tomato, watermelon, and sunflower.