Response of sweet cherry buds and twigs to temperature changes - evaluated by the determination of the degradation and synthesis of sucrose

This study was undertaken to determine the degradation and synthesis of sucrose (Suc) in sweet cherry buds and the twig tissue response to a sequence of environmental temperature changes (cold (orchard) - warm (controlled temperature of ∼22 °C) - cold (orchard)). The results of two years' (2016, 2017) findings were compared with the buds of trees and the buds of twigs in November/December in northeast Germany. The Suc content in the buds of trees and the buds of twigs under natural conditions was stable. Temperatures of ∼22 °C resulted in a significant (Suc) degradation (62%, from 39 to 15 mg/g DW) in the buds of twigs after 21 days (day of the year (DOY) 340). The significant re-synthesis (66%, to 25 mg/g DW after 21 days, DOY 361) in the orchard is noteworthy, and highlights the Suc value as a cryoprotective saccharide. The marked changes in the Suc, glucose, and fructose contents of the twigs exposed to a cold-warm-cold sequence (< DOY 319, DOY 319-340, DOY 340-361), lead to the conclusion that this adaptation is the result of tissue- and cold-specific sucrose invertases/synthases. The effect of low-temperature-active enzymes explains the role of Suc in the buds of trees during the winter rest. When using twigs for plant physiological examinations during the winter rest, results on a metabolite level should be considered when drawing conclusions concerning the overall tree physiology.