A role for PI-PLC in the generation of ABA-induced oscillations in [Ca2+]cyt in stomata

 

Abscisic acid induces oscillations in guard-cell cytosolic free calcium that involve phosphoinositide-specific phospholipase C.

by Staxén I., Pical C., Montgomery L. T., Gray J. E., Hetherington A. M., McAinsh M. R. (1999)

  1. Irina Staxén*,
  2. Christophe Pical,
  3. Lucy T. Montgomery*,
  4. Julie E. Gray,
  5. Alistair M. Hetherington*, and
  6. Martin R. McAinsh

Institute of Environmental and Natural Sciences, Department of Biological Sciences, Lancaster University, Lancaster LA1 4YQ, United Kingdom; and Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2UH, United Kingdom

in Proceedings of the National Academy of Sciences, USA 1999;96:1779-1784. –

CrossRef |PubMed | – 

http://www.pnas.org/content/96/4/1779

Abstract

Oscillations in cytosolic free Ca2+ concentration ([Ca2+]cyt) are an important component of Ca2+-based signal transduction pathways. This fact has led us to investigate whether oscillations in [Ca2+]cyt are involved in the response of stomatal guard cells to the plant hormone abscisic acid (ABA).

We show that ABA induces oscillations in guard-cell [Ca2+]cyt. The pattern of the oscillations depended on the ABA concentration and correlated with the final stomatal aperture.

We examined the mechanism by which ABA generates oscillations in guard-cell [Ca2+]cyt by using 1-(6-{[17β-3-methoxyestra-1,3,5(10)-trien-17-yl]amino}hexyl)-1H-pyrrole-2,5-dione (U-73122), an inhibitor of phosphoinositide-specific phospholipase C (PI-PLC)-dependent processes in animals.

U-73122 inhibited the hydrolysis of phosphatidylinositol 4,5-bisphosphate by a recombinant PI-PLC, isolated from a guard-cell-enriched cDNA library, in a dose-dependent manner.

This result confirms that U-73122 is an inhibitor of plant PI-PLC activity. U-73122 inhibited both ABA-induced oscillations in [Ca2+]cyt and stomatal closure. In contrast, U-73122 did not inhibit external Ca2+-induced oscillations in guard-cell [Ca2+]cytand stomatal closure.

Furthermore, there was no effect of the inactive analogue 1-(6-{[17β-3-methoxyestra-1,3,5(10)-trien-17-yl]amino}hexyl)-2,5-pyrrolidinedione on recombinant PI-PLC activity or ABA-induced and external Ca2+-induced oscillations in [Ca2+]cyt and stomatal closure.

This lack of effect suggests that the effects of U-73122 in guard cells are the result of inhibition of PI-PLC and not a consequence of nonspecific effects.

Taken together, our data suggest a role for PI-PLC in the generation of ABA-induced oscillations in [Ca2+]cyt and point toward the involvement of oscillations in [Ca2+]cyt in the maintenance of stomatal aperture by ABA.

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Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.

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