Short-term effects of plant hormones on membrane potential and membrane permeability of dwarf maize coleoptile cells (Zea mays L. d 1) in comparison with growth responses |
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Authors: | A. Nelles |
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Affiliation: | (1) Institut für Biochemie der Pflanzen, Akademie der Wissenschaften der DDR, Weinberg 3, DDR-401 Halle/S, German Democratic Republic |
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Abstract: | The membrane potential difference of dwarf maize coleoptile cells is increased by both 10-5moll-1 gibberellic acid (GA3) and indoleacetic acid (IAA) a few minutes after application. A final level is reached after 10–20 min. The membrane permeability ratio PNa:PK is altered by both hormones during the first 15 min after application, indicating a rapid effect on the membrane. Elongation growth of coleoptile segments, however, is only stimulated by IAA. The auxin-induced growth as well as the auxin effect on membrane permeability depends on the calcium ion concentration of the medium. It is concluded that IAA acts via a proton extrusion pump that is electrically balanced by a potassium ion uptake, driven by the electromotive force of the pump. The mode of action of GA3 on elongation growth is assumed to involve a process that depends on the physiologic state of the tissue and/or metabolic energy.Abbreviations IAA indoleacetic acid - GA3 gibberellic acid - FC fusicoccin - PD electric potential difference between the vacuole and the external medium |
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Keywords: | Auxin Calcium ions Cell growth Gibberellin Membrane permeability Membrane potential Zea |
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