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Physiology and Biochemistry

Identification of the Germination Self-inhibitor from Uredospores of Puccinia striiformis. V. Macko, Boyce Thompson Institute, Yonkers, NY 10701; E. J. Trione(2), and S. A. Young(3). (2)Agricultural Research Service, USDA; Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331; (3)Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331. Phytopathology 67:1473-1474. Accepted for publication 28 June 1977. Copyright 1977 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-67-1473.

The endogenous germination inhibitor from uredospores of the stripe rust fungus, Puccinia striiformis, was identified as methyl cis-3,4-dimethoxycinnamate. The inhibitor was extracted from field-collected spores with water, partitioned into ether, and purified by thin-layer and gas chromatography. The inhibitor activity was monitored with a germination assay employing fresh, water-washed, stripe rust uredospores. The chemical structure was confirmed by chromatogrphy in several systems and by mass spectrometry. The ED50 of the cis-form of the inhibitor was 4 ng/ml, whereas the trans-isomer had little or no activity as a germination inhibitor.

Additional keywords: wheat.