Exogenous Polyamines Stimulate Ethylene Synthesis by Soybean Leaf Tissues

Exogenous supply of spermine (Spm) markedly stimulated ethyleneevolution from intact soybean leaves of leaf discs, stronglyincreased the level of free 1-aminocyclopropane-1-carboxylicacid (ACC), and slightly stimulated ethylene forming-enzyme(EFE) activity Spm treatment also resulted in leaf epinastyand accelerated leaf senescence Ethylene stimulation was depressed,but not abolished, by light, and was suppressed by inhibitorsof ACC synthase and EFE activity Spermidine had a less pronouncedstimulatory effect on ethylene production whereas the diaminesputrescine and diaminopropane were without effect These resultscontrast with other reports indicating that di- and polyaminesinhibit ethylene biosynthesis in plants, and extend our previousresults on detached tobacco leaves exogenously treated withpolyamines Glycine max, ethylene, polyamines