Indoleacetic Acid and the Synthesis of Glucanases and Pectic Enzymes

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Abstract
Indoleacetic acid (IAA) and/or inhibitors of DNA, RNA or protein synthesis were added to the apex of decapitated seedlings of Pisum sativum L. var. "Alaska." At various times up to 4 days, enzymic protein was extracted from a segment of epicotyl immediately be10w the apex and assayed for its ability to hydrolyze polysaccharides or their derivatives. With the exception of amylase, the total amounts per segment of all of the tested enzymes increased due to IAA treatment. The deve10pment of [beta] -1,4-glucanase (cellulase) activity per unit of protein or fresh weight proceeded according to a typical sigmoid induction curve. Pectinase was formed for about 2 days in control segments and IAA treatment resulted in continued synthesis for at least another 2 days provided cell division took place. [beta] -1,3-glucanase and pectinesterase activities were only enhanced by IAA to the extent that total protein levels increased. Reaction mechanisms for these effects and functions for the enzyme during growth are discussed.