GA 3 Effects on Postharvest Alterations in Cell Membranes of Rose ( Rosa x Hybrida) Petals

Abstract

The postharvest increase in leakage of electrolytes from detached petals of rose flowers cvs. Mercedes, Sonata, and Golden Times, was suppressed following inhibition for 24 h in 20 mg L -1 solution of GA 3 , while leakage from petals of cv. Madelon was not affected by the GA 3 treatment. Similar suppression of leakage was also present when flower buds of cvs. Mercedes and Sonata were sprayed with 350 mg L -1 (1mM) solution of GA 3 . Postharvest decline of cell membrane fluidity and, to a larger extent, the decrease in membrane protein content were also suppressed following GA 3 application. In both control and GA 3 -treated petals, the decrease in membrane fluidity preceded the increase in ion leakage. The timecourse of this decrease coincided well with the time-course of the increase in membrane permeability in the control petals, but not in the petals from GA 3 -treated flowers. On the other hand, the time-course of the increase in membrane permeability corresponded well with the decrease in content of membrane protein in both control and GA 3 -treated petals. The decrease in content of total protein in petals of GA 3 -treated flowers was lower than that of control flowers. Comparison of electrophoretic protein profiles from both control and GA 3 -treated petals showed that the postharvest decomposition of proteins was inhibited by the GA 3 -treatment. The involvement of gibberellins in maintaining membrane integrity of rose flowers is discussed.