Metabolism of Labeled Exogenous Glucose in Fiber Flax Tissues

摘要

Labeled glucose solution was introduced into cut fiber flax plants (45-50 cm high) under a pressure of 0.1 bar for 30 min, 1, and 2 h using a special device. 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-~(14)C]-glucose transformation (23.5%). Metabolism of labeled glucose in the leaves exposed to sunlight yielded a set of metabolites similar to products of ~(14)CO_2 photoassimilation. In the shade, the pattern of ~(14)C distribution in labeled compounds of the alcohol/water soluble fraction was similar to that in the light in mature leaves; while in juvenile leaves, ~(14)C content decreased in sucrose and increased in organic and amino acids. In the shade, the incorporation of ~(14)C 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 sucrose and the polymers compete for photosynthetic ATP. Appearance of sucrose in the xylem 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 part of the shoot with the transpiration stream.