The Effects of Inhibitors of Polyamine and Ethylene Biosynthesis on Senescence, Ethylene Production and Polyamine Levels in Cut Carnation Flowers

The role of polyamine metabolism in the regulation of senescenceand ethylene evolution was examined in cut carnations. Endogenousconcentrations of spermine and spermidine did not change asflowers aged, but putrescine, their immediate biosynthetic precursor,increased dramatically and paralleled a sharp rise in ethylene.When D-arginine, difluoromethylarginine and methylglyoxal bis(guanylhydrazone)were used to inhibit specific steps in polyamine synthesis,ethylene production and the onset of senescence were promoted.In contrast, inhibition of ethylene by aminooxyacetic acid increasedthe level of spermine, presumably by increasing the availabilityof aminopropyl groups derived from S-adenosylmethionine (SAM)and required for the synthesis of polyamines from putrescine.These results suggest that the ethylene and polyamine biosyntheticpathways compete for SAM during senescence of carnation flowers. (Received September 1, 1983; Accepted January 7, 1984)