The relationship between acetyl content and sugar composition in expanding leaves of beech (Fagus sylvatica L.)

Abstract

Samples of beech (F. sylvatica) leaves were taken from the time of leaf emergence until leaf fall. They were extracted with boiling aqueous ethanol and the residues analyzed for their acetyl-group content and their content of sugars released by acid hydrolysis. The accumulation of acetyl groups closely paralleled that of xylose, and the 2 were present in approximately equimolecular proportions, except during the period of leaf expansion, when the acetyl-group/xylose ratio exceeded 3:2. The galactose present in each leaf reached a maximum as leaf expansion ceased and then declined during the period of rapid xylose accumulation. The results are discussed in relation to the known association of acetyl groups with xylans and pectic substances, and to the disappearance of constituents during cell-wall maturation.