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Cellular and Molecular Life Sciences CMLS

, Volume 54, Issue 3, pp 272–276 | Cite as

Stomatal guard cell responses to kinetin and natriuretic peptides are cGMP-dependent

  • M. Pharmawati
  • T. Billington
  • C. A. Gehring
Article

Abstract

Immunological evidence suggests that plants contain natriuretic peptides (NPs) and furthermore (3- [125I]iodotyrosol28) rat atrial NP (rANP) binds specifically to plant membranes. rANP and immunoaffinity-purified plant NP analogues also promote concentration-dependent stomatal opening. Here we report that kinetin, a synthetic cytokinin, and rANP induce stomatal opening in Tradescantia albiflora and that the effect of rANP is critically dependent on the secondary structure of the peptide hormone. The native circular molecule is active, whereas the linearized molecule shows no biological activity. Furthermore, kinetin- and rANP-induced stomatal opening is reversibly inhibited by two in hibitors of guanylate cyclase, LY 83583 and methylene blue. Stomatal opening is also induced in a concentration-dependent manner by the cell-permeant cyclic guanosine-3′,5′-monophosphate (cGMP) analogue 8-Br-cGMP, and this effect is prevented by the stomatal closure promoting plant hormone abscisic acid (ABA). We conclude that in guard cells kinetin and rANP pathways operate via guanylate cyclase upregulation, and we propose that ABA-induced closure is not cGMP-dependent.

Key words. Natriuretic peptide; kinetin; abscisic acid; cGMP; stomata; guard cells. 

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Copyright information

© Birkhäuser-Verlag, Basel 1998

Authors and Affiliations

  • M. Pharmawati
    • 1
  • T. Billington
    • 1
  • C. A. Gehring
    • 1
  1. 1.Deakin University, School of Biological and Chemical Sciences, Geelong, Victoria 3217 (Australia), Fax +61 3 5227 2022, e-mail: cage@deakin.edu.auAU

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