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Making sense out of Ca 2+ signals: their role in regulating stomatal movements
Author(s) -
ROELFSEMA M. ROB G.,
HEDRICH RAINER
Publication year - 2010
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2009.02075.x
Subject(s) - guard cell , cytosol , microbiology and biotechnology , extracellular , signalling , intracellular , signal transduction , abscisic acid , calcium signaling , crosstalk , biology , biophysics , chemistry , biochemistry , gene , enzyme , physics , optics
Plant cells maintain high Ca 2+ concentration gradients between the cytosol and the extracellular matrix, as well as intracellular compartments. During evolution, the regulatory mechanisms, maintaining low cytosolic free Ca 2+ concentrations, most likely provided the backbone for the development of Ca 2+ ‐dependent signalling pathways. In this review, the current understanding of molecular mechanisms involved in Ca 2+ homeostasis of plants cells is evaluated. The question is addressed to which extent the mechanisms, controlling the cytosolic Ca 2+ concentration, are linked to Ca 2+ ‐based signalling. A large number of environmental stimuli can evoke Ca 2+ signals, but the Ca 2+ ‐induced responses are likely to differ depending on the stimulus applied. Two mechanisms are put forward to explain signal specificity of Ca 2+ ‐dependent responses. A signal may evoke a specific Ca 2+ signature that is recognized by downstream signalling components. Alternatively, Ca 2+ signals are accompanied by Ca 2+ ‐independent signalling events that determine the specificity of the response. The existence of such parallel‐acting pathways explains why guard cell responses to abscisic acid (ABA) can occur in the absence, as well as in the presence, of Ca 2+ signals. Future research may shed new light on the relation between parallel acting Ca 2+ ‐dependent and ‐independent events, and may provide insights in their evolutionary origin.