Localized Effect of Polyamines on Chlorophyll Loss1

The effect of polyamines, spermidine and spermine, on senescence of detached leaves of rice, wheat and soybean was investigated. The decline of chlorophyll in rice leaf segments was promoted by polyamines during the first three days and in soybean leaf discs during the first day of incubation. However, the decline in chlorophyll was later retarded by polyamines. Polyamines were more effective in retarding senescence of detached wheat leaves at a higher concentration (10 mM) or in narrower segments. The retardation of chlorophyll loss by polyamines was mainly localized in those areas around the cut edges of detached leaves or near large veins of soybean primary leaves. This suggests that polyamines are not readily transported in leaf cells.