Temperature-induced Changes in Starch and Sugars in the Stem of Populus × canadensis «robusta»

Abstract

Summary Stem sections of Populus × canadensis «robusta» were taken at the beginning of the dormant season and subjected to temperatures of 10°, 5°, 0°, and −2 °C. Changes in starch content, sugar content, and in the pattern of individual sugars were followed up to four weeks. A strikingly linear relationship between starch breakdown and temperature is observed. The maximal rate of starch hydrolysis was 0.74 μg d -1 mg -1 DWT. A large pool of maltose was maintained at 5° and 10 °C which diminished, however, parallel to the formation of sucrose and its galactosides at lower temperatures. A linear but inverse relationship between starch content and the combined content of sucrose and its galactosides became apparent between −2° and 5 °C. These sugars accumulated from 13 % at 10 °C up to 69 % of the total sugar content at 0° and −2 °C. The results suggest that the temperature determines two separate events, the starch-maltose conversion and the synthesis of sucrose and its galactosides from the maltose moiety.