title: Calcium Requirement for Indoleacetic Acid-induced Acidification by Avena Coleoptiles.
abstract: The ionic specificity of IAA-induced acidification by Avena coleoptiles was studied, using zwitterionic, presumably impermeant buffers. The acidification was almost totally dependent on divalent cations with an order of effectiveness of Ca(2+) >/= Sr(2+) > Mn(2+), Mg(2+); whereas other polyvalent cations tested were ineffective. The Ca(2+) response was IAA-dependent. The CaCl(2) concentration was optimal at 0.3 to 1 mm and inhibitory at higher concentrations. Sr(2+) inhibited Ca(2+)-dependent acidification and monovalent cations such as K(+) did not induce additional acidification in the presence of optimal CaCl(2). These data are consistent with a mechanism for IAA-induced acidification involving a Ca(2+) -H(+) exchange.
authors: Department of Botany and Plant Pathology, Michigan State University, East Lansing, Michigan 48824.
authors: J D
authors: JD
authors: Cohen
authors: K D
authors: KD
authors: Nadler