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Physiology and Biochemistry

Phytotoxicity and Pathogenicity of Fusarium roseum to Red Clover. F. Blain, Plant Science Department, Macdonald College of McGill University, 21111 Lakeshore Road, Ste. Anne de Bellevue, Quebec H9X 1C0; M. Bernstein(2), S. Khanizadeh(3), and S. A. Sparace(4). (2)Merck Frosst Canada, Inc., P.O. Box 1005, Point Claire, Quebec H9R 4P8; (3)Agriculture Canada, 430 Gouin Blvd., St.-Jean-Sur-Richelieu, Quebec J3B 3E6; (4)Plant Science Department, Macdonald College of McGill University, 21111 Lakeshore Road, Ste. Anne de Bellevue, Quebec H9X 1C0. Phytopathology 81:105-108. Accepted for publication 30 August 1990. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/Phyto-81-105.

Extracts of culture filtrates from Fusarium roseum are phytotoxic to germinating red clover (Trifolium pratense) seeds. All isolates tested yielded phytotoxic extracts composed of several phytotoxic components. Extracts from the most pathogenic isolate showed only slight host specificity for susceptible red clover seedlings; cucumber (Cucumis sativus) and timothy (Phleum pratense) were most resistant at the lowest concentrations tested. Phytotoxic fractions contain primary amino acids and secondary N-substituted amino acids. Preparative thin-layer chromatography yielded two major phytotoxic fractions: a crude crystalline material containing valine residues and an oil containing valine, isovaleric acid, and aromatic phenyl moieties. These phytotoxins resemble the cyclodepsipeptide antibiotics produced by other pathogenic fungi and by other F. roseum isolates.

Additional keywords: crown and root rot of clover.