EFFECTS OF INDOLEACETIC ACID ON INTRACELLULAR DISTRIBUTION OF BETA-GLUCANASE ACTIVITIES IN PEA EPICOTYL

β-1,4-Glucanase (cellulase) and β-1,3-glucanase activities were estimated in various subfractions of the growing region of decapitated Pisum sativum epicotyls. Treatment of the epicotyl apex with the hormone indoleacetic acid (IAA) caused total and specific cellulase activity to increase, first and most markedly, in a microsomal fraction containing membrane-bound ribosomes and eventually in fractions containing soluble enzyme and wall material. The responses did not occur in the presence of actinomycin D or during growth after treatment with other hormones. In the absence of IAA, cellulase activity disappeared within a few days from microsomal and wall fractions. It is concluded that cellulase is synthesized via an IAA-dependent mechanism and is inactivated extracellularly. In the same system, β-1,3-glucanase activity increased greatly with time but microsomes failed to show preferential enrichment at any stage of development and IAA treatment failed to affect the increase unilaterally. © 1968.