Effect of sucrose exposure on the xylem anatomy of three temperate species

Abstract

ABSTRACT This study is a continuation of research on the role of sucrose in figured wood formation in temperate trees. Different concentrations of sucrose solutions were administered for 7 weeks to trunk tissues of Betula pendula Roth, Alnus incana (L.) Moench and Populus tremula L. Then xylem anatomy was examined with particular emphasis to the number of vessels and the spatial orientation of xylem elements. In B. pendula and A. incana a high level of exogenous sucrose caused a reduction in the number and size of xylem vessels, even to the point of absence of vessels. Sucrose concentrations of 100 and 200 g l-1 induced the formation of curly grain and anomalous club-shaped rays in xylem of B. pendula. Populus tremula xylem was not significantly altered by the experiment; the xylem anatomy was more seriously affected by wounding than by sucrose. In B. pendula and A. incana the wood formed during the experiment was similar to figured wood of these species. The decrease in the number and size of vessels in the xylem formed during the experiment possibly suggests that high concentrations of sucrose lead to a decline in the level of physiologically active auxin. Changes in the orientation of xylem elements points to a disruption of basipetal auxin transport. Further biochemical and physiological studies are needed to provide more comprehensive understanding of the relationship between sucrose and auxin during the development of figure in wood.