The interaction between polyamines and ethylene is still not clear for floral tissues. The aim of the present paper is to examine the senescence on the isolated petals of carnation (Dianthus caryophyllus cv. Desio) but not the whole flower in an attempt to clarify the exact role of polyamines. Petals were treated with putrescine (Put; 0.0, 1.0, 10mM), spermidine (Spd; 0.0, 1.0, 10mM), spermine (Spn; 0.0, 1.0, 10mM), Put+Spd (1.0mM), Put+Spn (1.0mM). The fresh weight of petals in all 10mM treatment was decreased less than those in the other treatments at all times but there were no significant differences. The differences in ethylene production were significant. In petals maintained in 10mM of polyamines, ethylene production was completely inhibited until 13 days and senescence was considerably retarded. However, ethylene productions in 1.0mM polyamines treatments were delayed 2-3 days with reduced amounts. These results suggest that high concentrations of polyamines retard senescence and completely inhibit ethylene production. ACC content, activities of ACC synthase and SAM decarboxylase were analyzed. Finally, the role of SAM in ethylene and polyamines biosynthesis will be discussed.
Ki-Cheol Son and Y. Chae
Ki-Cheol Son, Y. Chae, and Y. Lee
During the aging of H. syriacus flower, biosynthetic pathways of ethylene and polyamines, their interactions, and their effects on senescence were investigated. The evolution of ethylene in ephemeral flower was rapidly increased immediately after initiation of in-rolling of corolla at which EFE activity became maximum peak. After that, EFE activity was gradually decreased even though the aging was continued. Ethylene production was, however, slightly inhibited by the treatments of AOA and putrescine. The activity of ACC synthase and SAM decarboxylase were most rapidly increased at the time of 36th hrs. The contents of ACC and MACC were gradually increased from the early stage. However, ACC contents was decreased at the final stage but MACC was continuously increased. In normal condition, endogenous level of polyamines exists in the order of putrescine>spermidine>spermine. Putrescine was reduced from the initial point of aging, but spermidine and spermine were reduced from the middle and final stage of aging, respectively.