Correlative changes in sucrose uptake, ATPase activity and membrane fluidity in carnation petals during senescence

Apparent sucrose uptake. ATPase activity and membrane fluidity changes were studied during the development and senescence of carnation flowers ( Dianthus caryophyllus L., cv. Cerise Royallette). Typical changes associated with senescence of a cut flower, such as respiration, ethylene production and fresh weight, were measured. Concomitant with a rise in respiration and ethylene production and a decline in fresh weight, a sharp decrease in apparent sucrose uptake was observed. Sucrose uptake was pH dependent (pH optimum, 5.5) and influenced by membrane integrity. Apparently, the activity of ATPase is related to sucrose uptake, because similar changes occurred during flower development. In addition, the activity of ATPase was well correlated with membrane fluidity.
It is suggested that sucrose uptake is controlled by ATPase activity, which in turn is modulated by membrane lipid fluidity. The decline in membrane fluidity associated with senescence leads to a corresponding reduction in ATPase activity and sucrose uptake. Further evidence supporting this view comes from experiments in which senescence was enhanced by 1-aminocyclopropane-l-carboxylic acid. It shortened the time to decline in fresh weight, rise in respiration and ethylene production. In parallel, reduction in membrane fluidity, ATPase activity and sucrose uptake were observed.