GROWTH-INHIBITION OF BOTRYTIS-CINEREA BY COMPOUNDS INTERFERING WITH POLYAMINE METABOLISM

Several inhibitors of ornithine and arginine decarboxylases reduced growth of the fungus Botrytis cinerea cultured on Czapek Dox agar. Of these, the most effective were difluoromethylornithine (DFMO), dehydromonofluoromethylornithine, difluoromethylarginine and dehydromonofluoromethylarginine. The growth inhibition due to 1 mM-DFMO could be partially reversed with 1 μM-putrescine. Other compounds causing significant reversal of DFMO-mediated growth inhibition included diaminopentane (cadaverine), diaminoheptane, spermidine, 7,7-difluorospermidine, spermine, bis(2-aminoethyl)amine, 2-hydroxy-1,3-diaminopropane, monoacetylputrescine, butenediamine and aminoguanidine. Some compounds, which were relatively innocuous by themselves, increased growth inhibition due to DFMO. Notably effective compounds were methylacetylenicputrescine, aminooxyaminopropane, butynediamine, 2,2-difluoroputrescine, diacetylputrescine, methylglyoxal bis(guanylhydrazone), streptomycin, certain methylated amines, and cyclohexylamine and related compounds. Growth inhibition due to a homologous series of diguanidines [NH2C(=NH)NH(CH2)(x)NHC(=NH)NH2] was also tested. These were especially effective when x = 12, and when x = 5 or 6. In general, the results suggest that amino-acid-based inhibitors of ornithine decarboxylase have a greater permeability than amine-based inhibitors.