EFFECT OF POLYAMINE BIOSYNTHESIS INHIBITORS ON POLYAMINE LEVELS IN BEAN SEEDLINGS

alpha-Difluoromethylornithine (DFMO) and alpha-difluoromethylarginine (DFMA), inhibitors of polyamine (PA) biosynthesis, are known to control fungal infections of plants. To see if these inhibitors affect plant polyamine metabolism and growth, changes in endogenous polyamine (PA) pools of bean plant (Phaseolus vulgaris L. (PA) pools of bean plants (Phaseolus vulgaris L. var Pinto) were examined following a single spray of DFMO and DFMA onto unifoliolate leaves. The level of PAs did not decline after inhibitor treatment; rather putrescine and spermidine levels rose in plants sprayed with inhibitor. PA concentrations were greater in unexpanded trifoliolate leaves, compared with unifoliolate leaves, suggesting that PA biosynthesis is greatest in rapidly growing parts of the plant. There was no effect of DFMO or DFMA spray on growth of the plants. These findings further substantiate the idea that DFMO and other PA inhibitors might be used to protect crop plants from pathogenic fungi.