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Prevention of Infection of Soybean Seeds by Colletotrichum truncatum by Polyamine Biosynthesis Inhibitors. A. Gamarnik,Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Buenos Aires, Current address: Gladstone Institute of Virology and Immunology, P.O. Box 419100, San Francisco 94141; R. B. Frydman(2), and D. Barreto(3). (2)Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, Buenos Aires; (3)Departamento de Patología Vegetal, INTA, Castelar, Provincia de Buenos Aires, Argentina. Phytopathology 84:1445-1448. Accepted for publication 24 August 1994. Copyright 1994 The American Phytopathological Society. DOI: 10.1094/Phyto-84-1445.

The mechanism-based inhibitors of polyamine biosynthesis α-difluoromethylornithine (DFMO) and α-difluoromethylarginine (DFMA) were used to prevent soybean seed infection by the pathogenic fungus Colletotrichum truncatum. DFMA (2 mM) and DFMO (4 mM) protected soybean seeds against infection by C. truncatum. The effect of these inhibitors on the growth of the fungus was examined. Similar sensitivity to both DFMO and DFMA was observed; however, growth inhibition was reversed by the addition of putrescine or spermidine. This fungus was found to contain both ornithine and arginine decarboxylases. The intracellular polyamine levels of putrescine, spermidine, and spermine were lowered by the presence of either DFMA or DFMO. Spermidine was the predominant polyamine found in this fungus. Because DFMA, contrary to DFMO, did not affect seed germination, DFMA treatment could be used to prevent infection of soybean seeds by C. truncatum.

Additional keywords: Glycine max.