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Induced Ca 2+ uptake and callose synthesis in suspension‐cultured cells of Catharanthus roseus are decreased by the protein phosphatase inhibitor okadaic acid
Author(s) -
Kauss Heinrich,
Jeblick Wolfgang
Publication year - 1991
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1991.tb08737.x
Subject(s) - okadaic acid , catharanthus roseus , callose , biochemistry , digitonin , phosphatase , dephosphorylation , biology , phosphorylation , chemistry , enzyme , cell wall
Subtoxic concentrations of the saponin digitonin. the polyene antibiotic amphotericin B and the bacterial phytotoxin syringomycin induce increased uptake of 45 Ca 2+ into suspension‐cultured plant cells and a rapid Ca 2+ ‐dependent defense response, callose synthesis. Both reactions were inhibited by preincubation of the cells with okadaic acid, a specific inhibitor of type 1 and type 2A protein phosphatases. These results suggest that Ca 2+ uptake induced by the above agents does not occur due to unspecific perturbation of plasma membrane permeability but involves transport proteins which are controlled by protein phosphorylation/dephosphorylation. Phosphoproteins appear also to be involved in the regulation of callose synthesis, although it remains open whether this control is effected at the level of Ca 2+ transport or at the 1,3‐ß‐glucan synthase involved in deposition of the polymer.