Hypoosmotic shock induces increases in cytosolic Ca2+ in tobacco suspension-culture cells

• Published in: Plant physiology (Bethesda) Vol. 113; no. 2; pp. 587 - 594
• Main Authors: Takahashi, K. (Nagoya University, Japan.), Isobe, M, Knight, M.R, Trewavas, A.J, Muto, S
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01.02.1997
• Subjects: Biological and medical sciences; CALCIO; CALCIUM; cell suspension culture; CHOIX DE LA DATE; CITOPLASMA; CULTIVO DE CELULAS; CULTURE DE CELLULE; CYTOPLASME; cytosol; ECHANGE D'ION; ELECCION DE LA EPOCA; EXPRESION GENICA; EXPRESSION DES GENES; Fundamental and applied biological sciences. Psychology; gene expression; GENETICA; GENETIQUE; INTERCAMBIO IONICO; luminescence; measurement; MEDICION; MESURE; NICOTIANA TABACUM; osmotic pressure; Plant physiology and development; PLANTAS TRANSGENICAS; PLANTE TRANSGENIQUE; PRESION OSMOTICA; PRESSION OSMOTIQUE; PROPIEDADES OPTICAS; PROPRIETE OPTIQUE; stress response; transgenic plants; Water and solutes. Absorption, translocation and permeability; Osmotic shock; Cell culture; Calcium; Dicotyledones; Angiospermae; Spermatophyta; Solanaceae; Biological accumulation; Membrane channel; Nicotiana tabacum; Cytosol
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.113.2.587

Hypoosmotic shock treatment increased cytosolic Ca2+ ion concentration ([Ca2+]cyt) in tobacco (Nicotiana tabacum) suspension-culture cells. [Ca2+]cyt measurements were made by genetically transforming these cells to express apoaequorin and by reconstituting the Ca2+-dependent photoprotein, aequorin, in the cytosol by incubation with chemically synthesized coelenterazine. Measurement of Ca2+-dependent luminescence output thus allowed the direct monitoring of [Ca2+]cyt changes. When cells were added to a hypoosmotic medium, a biphasic increase in [Ca2+]cyt was observed; an immediate small elevation (phase 1) was observed first, followed by a rapid, large elevation (phase 2). Phase 1 [Ca2+]cyt was stimulated by the V-type ATPase inhibitor bafilomycin A1. Phase 2 was inhibited by the protein kinase inhibitor K-252a and required the continued presence of the hypoosmotic stimulus to maintain it. Although Ca2+ in the medium was needed to produce phase 2, it was not needed to render the cells competent to the hypoosmotic stimulus. If cells were subject to hypoosmotic shock in Ca2+-depleted medium, increases in luminescence could be induced up to 20 min after the shock by adding Ca2+ to the medium. These data suggest that hypoosmotic shock-induced [Ca2+]cyt elevation results from the activity of a Ca2+ channel in the plasma membrane or associated hypoosmotic sensing components that require Ca2+-independent phosphorylation and a continued stimulus to maintain full activity