Effects of Indoleacetic Acid on the Utilization of Acetate-1-C14 by Pea Stem Slices.

Abstract

Indoleacetic acid (IAA) in growth promoting concentrations (2.5 x 10"5 and 2.5 x 10-4 [image]) profoundly affects the utilization of acetate-1-C14 by stem slices of pea seedlings (var. Alaska) in experiments involving pre-treatment of the slices in non-radioactive solutions containing the auxin followed by exposure of the slices to acetate-1-C14 for 15 or 30 minutes. Incorporation of radioactivity into pectic substances, lipides, polyuronide hemicelluloses and a mixture of unidentified colloidal substances is inhibited. Incorporation into organic acids and CO2 is stimulated by IAA. These responses to IAA are enhanced by extension of pre-treatment and by additions of Ca and unlabeled acetate to the pre-treatment solutions. Slices pre-treated with KC1 or CaCL, only show no impressive response to IAA supplied with acetate-1-C14 fn the second part of the experiment. Slices incubated for 4 hours in a solution of acetate-1-C14 show little response to IAA at 2.5 x 10"5 [image], but their capacity to incorporate activity in pectic substances is strongly inhibited by IAA at 2.5 x 10"4 [image].