Prevention of Infection of Soybean Seeds byColletotrichum truncatumby Polyamine Biosynthesis Inhibitors

Abstract

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