Studies on the Chemistry of the Living Bark of the Black Locust Tree in Relation to Frost Hardiness. IV. Effects of Ringing on Translocation, Protein Synthesis and the Development of Hardiness

Abstract

Seasonal changes which occur in the water-insoluble protein nitrogen, the water-soluble protein nitrogen, the water-soluble non-protein nitrogen, and the reducing and non-reducing sugar contents of the living bark tissue of normal black locust trees and the relationships that these changes bear to seasonal variations in the frost hardiness of this tissue have been reported earlier (2, 22). These studies were initial steps in an analytical approach to the problem of the biochemistry of frost hardiness. The objective of this approach is the identification of those changes in biochemical composition of the cells which occur in association with their changes in hardiness. Such information, while not necessarily supplying a basis for explaining the physiological mechanism involved in hardiness, constitutes a necessary advance in the attempt to elucidate this mechanism. Among the seasonal changes in the chemical composition of the tissues which were followed, those which occurred in the water-soluble proteins showed the best correlation with frost hardiness changes. This relationship could have been fortuitous rather than causal, i.e., it could have arisen from a simultaneous but independent normal seasonal variation in the protein content of the cells and in their hardiness. Included in these earlier studies were results of hardiness tests and chemical analyses performed on the bark of the stumps of trees from which the crown and upper trunk had been removed in winter. Dehardening of the bark of the stumps in the spring was observed to be abnormally slow and the seasonal decrease in protein which is observed in normal trees was also delayed in proportion to the observed retention of hardiness. This apparently resulted from the elimination of the upward translocation of bark cell constituents from the trunk to the crown which normally occurs in the spring in response to the demands made by the new flush of growth. Even under such unseasonal conditions, the association of soluble protein content with hardiness was observed. Contrasted to this,