Patterns of development of glycosidase activities in the pea epicotyl

Abstract

Rates of hydrolysis of α- and β-linked glucosides and galactosides were compared in reaction mixtures containing nitrophenol derivatives, maltose, or cellobiose as substrates, plus enzyme derived from various parts of the third internode of the pea epicotyl. β-Glucosidase activity (EC. 3.2.1.21) per unit fresh weight, protein, or DNA was concentrated in meristematic tissues (plumule and hook) and nearly absent from adjacent growing and maturing regions in the internode. The other glycosidase activities showed no such specific localization. β-Glucosidase was also the only one of these enzymes that increased in specific activity in the decapitated epicotyl after treatment with indoleacetic acid. The increase (about twofold in 2 days) occurred if cell division was evoked at the same time. Treatment with gibberellic acid had little effect on any glycosidase activity. It is concluded that β-glucosidase activity may have been especially useful in cells during or shortly after cytokinesis, but none of the glycosidase activities were needed specifically for cell elongation or expansion.