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Plant Cell. 1991 Apr;3(4):333-344.

Role of Calcium in Signal Transduction of Commelina Guard Cells.

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  • 1Institute of Cell and Molecular Biology, University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh EH9 3JH, United Kingdom.


The role of cytosolic Ca2+ in signal transduction in stomatal guard cells of Commelina communis was investigated using fluorescence ratio imaging and photometry. By changing extracellular K+, extracellular Ca2+, or treatment with Br-A23187, substantive increases in cytosolic Ca2+ to over 1 micromolar accompanied stomatal closure. The increase in Ca2+ was highest in the cytoplasm around the vacuole and the nucleus. Similar increases were observed when the cells were pretreated with ethyleneglycol-bis-(o-aminoethyl)tetraacetic acid or the channel blocker La3+, together with the closing stimuli. This suggests that a second messenger system operates between the plasma membrane and Ca2+-sequestering organelle(s). The endogenous growth regulator abscisic acid elevated cytosolic Ca2+ levels in a minority of cells investigated, even though stomatal closure always occurred. Ca2+-dependent and Ca2+-independent transduction pathways linking abscisic acid perception to stomatal closure are thus indicated.

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