Glutathione content in peach buds in relation to development and release of rest

Abstract

Glutathione content was determined in buds of one-year-old potted peach (Prunus persica L.) trees during rest development and release from rest. The content of reduced (GSH) and oxidized glutathione (GSSG) changed with the accumulation of chilling units. GSH and GSSG content decreased in the early phases of rest, and then increased at maximum rest. GSH content continued to increase and peaked on 1 Dec at 860 chill units, and then dropped during the quiescent stage. It appears that the increase of GSH during chilling was closely associated with the breaking of rest. In contrast, GSSG showed only slight increase from Oct to Dec. Glutathione levels induced by the rest-breaking chemical, hydrogen cyanamide, were also studied throughout the rest period. Five concentrations of cyanamide (0, 0.125, 0.25, 0.5, and 1.0 M) were applied on 1 Oct, 15 Oct, 1 Nov, 15 Nov, 1 Dec, and 15 Dec, 1990. Cyanamide treatments caused a depletion of GSH within 12 h followed by a large increase 24 h after treatment, whereas the untreated plants showed a relatively constant level of GSH and GSSG during this time. The changes in GSH content induced by cyanamide were inversely related to the cyanamide concentration applied. It appears that the extent of GSH change was dependent on both the physiological status of the bud and the cyanamide concentration. At maximum rest, the plants were more resistant to cyanamide treatment and this coincided with the highest level of cyanamide-induced GSH. © 1992. The Japanese Society of Plant Physiologists (JSPP).