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Ecology and Epidemiology

Herbicolin A Associated with Crown and Roots of Wheat after Seed Treatment with Erwinia herbicola B247. H. -J. Kempf,Ciba-Geigy Ltd., Basle, Switzerland; P. H. Bauer, and M. N. Schroth. Department of Plant Pathology and Weed Science, Colorado State University, Fort Collins 80523; and Department of Plant Pathology, University of California, Berkeley 94720. Phytopathology 83:213-216. Accepted for publication 12 November 1992. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/Phyto-83-213.

Wheat seeds were treated with a strain of Erwinia herbicola that produces herbicolin A. After 4 daysí growth in a natural soil, the antibiotic was extracted from washed roots and crowns. Herbicolin A was detected in crowns and the first centimeter of roots by a thin-layer chromatography overlay inhibition assay. The chromatography technique was superior to high-performance liquid chromatography because of its sensitivity and the fact that it did not require purification of tissue extracts. Quantities of herbicolin A averaging 2.7 μ g/g dry weight were detected in crowns of seedlings grown in natural field soil with an average of 3 ◊ 109 colony-forming units per gram dry weight of tissue. The antibiotic was not detected in extracts of roots treated with a transposon mutant lacking herbicolin production. Concentration of antibiotic extracted from the tissue exceeded that which could be recovered from a bacterial culture of comparable population density to the colonizing bacteria, indicating in situ production of herbicolin. This is the first report of in situ antibiotic production in natural soil with subsequent absorption by plants.

Additional keywords: biological control.