The changes in redox status of ascorbate in stem tissue cells during Scots pine tree growth

Abstract

The contents of ascorbate (AsA) and dehydroascorbate (DHA) and their ratio, showing cellular redox state of AsA, were studied in the cells of the separate tissues at different levels of Pinus sylvestris L. stem during early- and latewood formation. Morphological status of the cells in the tissues and the content of soluble carbohydrates were also estimated. The cellular redox potential of AsA has been found to depend on the type of tissue, cell development degree, the level of stem and the type of forming wood. The content of AsA and AsA/DHA ratio in the cells of non-conducting phloem along the stem were higher than in mature xylem and less during earlywood than latewood formation. The cells of conducting phloem and forming xylem, as the principal tissues taking part in annual ring wood formation, differed in the content of acids in the course of early and late xylem formation. Along the stem, the content of AsA decreased in conducting phloem cells and increased in the cells of forming xylem during both early- and latewood formation. The AsA/DHA of conducting phloem during earlywood formation was greatest below the stem and diminished to the top of the tree, while in the course of latewood development it was similar at all levels. In forming xylem AsA/DHA increased to the top of tree during the early xylem formation and decreased in late xylem that indicates the differences in oxidation-reduction reactions into the cells of two type of forming wood. The data are discussed according to morphological development of cells and the content of carbohydrates.

Keywords

• Pinus sylvestris L.
• levels of stem
• non-contacting phloem
• conducting phloem
• forming xylem
• mature xylem
• ascorbate/dehydroascorbate ratio