This Article Full Text (PDF) A correction has been published Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (9) Citing Articles via Google Scholar Google Scholar Articles by Martin, H. V. Articles by Pilet, P.-E. Search for Related Content PubMed PubMed Citation Articles by Martin, H. V. Articles by Pilet, P.-E. Agricola Articles by Martin, H. V. Articles by Pilet, P.-E.

Development and Growth Regulation

Effect of pH on IAA Uptake by Maize Root Segments

Institute of Plant Biology and Physiology, Biology Building, University of Lausanne, 1015 Lausanne, Switzerland

The uptake of [5-³H]indoleacetic acid (IAA) by Zea mays L. root segments involves nonsaturable and saturable processes. The pH optimum of the saturable component was found to be 5.0. The proton ionophore carbonylcyanide p-trifluoromethoxyphenylhydrazone inhibited at 100 micromolar the saturable component of IAA uptake but had no effect on non-saturable uptake. This indicates that the saturable component of IAA uptake is dependent on the proton gradient across the plasmalemma. The high level of proton extrusion in the elongation zone of the root will stimulate nonsaturable and saturable uptake of IAA in that zone.