ENDOGENOUS POLYAMINE LEVELS AND DARK-INDUCED SENESCENCE OF DETACHED CORN LEAVES

The role of endogenous polyamines in the regulation of dark-induced senescence of detached corn leaves was investigated. Putrescine, spermidine, and diaminopropane were all present throughout senescence, but spermine was undetectable. Preceding the commencement of dark-induced senescence, there was a marked increase in putrescine levels. A slight increase in levels of spermidine and diaminopropane occurred only at an advanced stage of senescence. D-arginine and alpha-methylornithine caused a reduction in the levels of putrescine and a retardation of senescence. Benzyladenine, which retarded senescence, significantly decreased the levels of putrescine. The results suggest that an increase in endogenous putrescine level is likely to be the factor responsible for dark-induced senescence of detached corn leaves.