Metabolism of Labeled Exogenous Glucose in Fiber Flax Tissues

Abstract

A labeled glucose solution was introduced into cut fiber flax plants (45-50 cm high) using a special unit under a pressure of 0.1 atm for 30 min, 1, and 2 h. The highest quantities of labeled carbon were revealed in the woody tissue. Sucrose made up a considerable proportion in low molecular weight products of [ [2-14C]-glucose transformation (23.5%). Metabolism of labeled glucose in the leaves exposed to sunlight yielded a set of metabolites similar to products of 14CO2 photoassimilation. In the shade, the pattern of 14C distribution in labeled compounds of the water/alcohol soluble fraction remained similar in mature leaves, while in juvenile leaves, 14C content decreased in sucrose and increased in organic and amino acids. In the shade, the incorporation of 14C into starch and hot water soluble polysaccharides increased at the expense of the acetone fraction (lipids and pigments), water/salt soluble proteins, and cellulose. Low light conditions increased the radioactivity ratio of sparingly soluble (KOH and Triton X-100 soluble) proteins to albumins and globulins. We propose that the synthesis of components of the photosynthetic apparatus in juvenile leaves is directly powered by photosynthesis and the photosynthesis of glucose and the polymers compete for ATP energy. Appearance of sucrose in the woody tissue is due to its release from the phloem to the stem apoplast and the radial transfer to the xylem, where it is transported to the upper shoot with the transpiration flow.