Effect of IAA on Synthesis and Activity of the Plasma Membrane H+-ATPase of Sunflower Hypocotyls, in Relation to IAA-induced Cell Elongation and H+ Excretion

• Published in: Journal of plant physiology 1995-03, Vol.145 (5-6), p.717-725
• Main Authors: Cho, Hyung-Taeg, Hong, Young-Nam
• Format: Article
• Language: English
• Subjects: ACIDE INDOLACETIQUE; ACIDO INDOLACETICO; ACTIVIDAD ENZIMATICA; ACTIVITE ENZYMATIQUE; ADENOSINA TRIFOSFATASA; ADENOSINE TRIPHOSPHATASE; Adenosintriphosphatase; ALARGAMIENTO DEL TALLO; ALLONGEMENT DE LA TIGE; Auxin; Auxin (IAA); auxin-induced elongation; auxin-induced H+ excretion; Biochemie; Biological and medical sciences; CELL MEMBRANES; Cell physiology; CELLS; CELLULE; CELULAS; Enzymaktivitaet; ENZYMIC ACTIVITY; EXCRECION; EXCRETION; Fundamental and applied biological sciences. Psychology; Gemuesebau; Helianthus; HELIANTHUS ANNUUS; Helianthus annuus L; HIDROGENO; HIPOCOTILOS; HYDROGEN; HYDROGENE; HYPOCOTYLE; HYPOCOTYLS; Hypokotyl; IAA; MEMBRANAS CELULARES; MEMBRANE CELLULAIRE; Pflanzenphysiologie; Plant physiology and development; Plasma membrane and permeation; plasma membrane H+-A TPase; Plasmamembran; STEM ELONGATION; sunflower hypocotyl; Wachstumsregulator; Wasserstoffexkretion; Zellwachstum
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/S0176-1617(11)81286-1

The effect of indole-3-acetic acid (IAA) on the amount and the activity of the plasma membrane (PM) H+-ATPase (EC 3.6.1.35) of sunflower (Helianthus annuus L.) hypocotyls, in relation to IAA-induced cell elongation and H+ excretion, was investigated. IAA increased the elongation and the H+ excretion of hypocotyl segments about five times over the control within 2 h. Protein synthesis inhibitor (cycloheximide), RNA synthesis inhibitor (cordycepin), calcium-channel blocker (verapamil), and secretion inhibitors (monensin and brefeldin A) considerably reduced the IAA-induced elongation and H+ excretion. When these inhibitors were added 60 min after IAA treatment, in which a maximal IAA-induced elongation rate is maintained, they all inhibited elongation with a short lag time (less than 10 min). In protein slot blots, using an antibody against Arabidopsis thaliana PM H+-ATPase, IAA did not increase the amount of PM H+-ATPase in the extracted plasma membrane of sunflower hypocotyl segments. The above inhibitors, moreover, did not decrease the PM H+-ATPase amount up to 2 h after the treatments, which means that the enzyme is not subject to rapid turnover. IAA, when added to both the isolated membranes or the segments, had a little effect on the PM H+-ATPase activity. These results show that the IAA-induced elongation and H+ excretion may need some factors with rapid turnover that exist in the plasma membrane or are related to the secretory pathway, but PM H+-ATPase does not belong to these factors.