Abstract
A particulate fraction from pollen tubes and ungerminated pollen of Lilium longiflorum incorporated (14)C-glucose from UDP-glucose-(14)C into a lipid fraction and into beta-1, 3-glucan. Partial hydrolysis of the glucan yielded laminaribiose as the only radioactive disaccharide. The preferred substrate was UDP-glucose, and enzyme activity was stimulated by glucose and by beta-linked di- and trisaccharides. Enzyme from growing pollen tubes synthesized beta-1, 3-glucan more rapidly and produced a higher proportion of alkali-insoluble glucan than did enzyme from ungerminated pollen. The onset of pollen tube growth may be dependent on altered activity of beta-1, 3-glucan synthase.