Carbohydrate Physiology of Orchid Seedlings. Ii. Hydrolysis and Effects of Oligosaccharides

Orchid seedlings were grown on nutrients containing cold‐sterilized sugars as sources of carbon. Action by an extra‐cellular invertase was implied from the hydrolysis by seedlings of sugars containing α‐D‐glucopyranosyl‐(1 → 2)‐β‐D‐fructofuranoside bonds. D‐galactosides (α and β) were also hydrolyzed, indicating the presence of extracellular galactosidases. Hydrolysis of α‐D‐fructofuranosides and α‐D‐galactosides decreased with increasing molecular weight. Seedling damage and growth retardation were paralleled by galactose accumulation in the substrate. Rupture of tonoplast and evagination of the nuclear envelope suggests that this sugar may alter some factor(s) responsible for the maintenance of membrane permeability.