Abstract: The role of polyamines in the regulation of senescence was examined in excised wheat leaves. The polyamines–putrescine (Put) spermidine (Spd) and spermine (Spm) prevented The loss of chlorophyll normally associated with senescence of leaf tissue maintained in darkness. P. olyamines were also highly effective in retarding earlier event–the rise in protease activity of leaf senescence, prior to chlorophyll loss. A good quantitative correlation was found between chlorophyll and MDA content. After 0.5 mmol/1 Spd was applied, SOD activity was stabilized and POD activity was hardly changed. On the contrary, SOD activity dedlined and POD activity increased in the control. The analysis of isozyme showed that a new band of POD isozyme was found after incubation for 48 hours, but it was not observed at the same time after the treatment with 0.5 mmol/1 Spd. On the other hand, SOD isozyme had no change in senescing process or after the treatment. In the dark-induced senescence, ADC and ODC activity decreased. The kinetin promoted ADC and ODC activity compared with that of the control. The antisenescence function of kinetin was reversed partially by DFMO. A possible reason for polyamines antisenescence function and their relation to the plant hormones is discussed.

Key words: Polyamine, Putrescine, Spermine, Spermidine, Senescence Wheat