Planta

, Volume 214, Issue 5, pp 775–782

The sensitivity of ABI2 to hydrogen peroxide links the abscisic acid-response regulator to redox signalling

  • Michael Meinhard
  • Pedro L. Rodriguez
  • Erwin Grill
Original Article

DOI: 10.1007/s00425-001-0675-3

Cite this article as:
Meinhard, M., Rodriguez, P.L. & Grill, E. Planta (2002) 214: 775. doi:10.1007/s00425-001-0675-3

Abstract.

ABI1 and ABI2 are two protein serine/threonine phosphatases of type 2C (EC 3.1.3.16) that act as key regulators in the responses of Arabidopsis thaliana (L.) Heynh. to abscisic acid (ABA). They are involved in the control of ABA-mediated seed dormancy, stomatal closure and vegetative growth inhibition. Analysis of the enzymatic properties of ABI2 revealed high sensitivities towards protons and unsaturated fatty acids. Furthermore, the protein phosphatase activity of ABI2 is very sensitive to H2O2, which has recently emerged as a secondary messenger of ABA signalling. Upon H2O2 challenge, ABI2 is rapidly inactivated with an IC50 value of 50 µM in the presence of reduced glutathione. Inhibitor studies with phenylarsine oxide and manipulation of the redox status of ABI2 in vitro indicate that oxidation of critical cysteine residue(s) is responsible for inactivation. The levels of the major cellular thiol compounds cysteine and glutathione in leaves and seedlings of A. thaliana are compatible with a physiological role of H2O2 in regulating ABI2 activity. ABI2 is considered to exert negative regulation on ABA action. Thus, transient inactivation of this protein phosphatase by H2O2 would allow or enhance the ABA-dependent signalling process. In conclusion, ABI2 represents a likely target for redox-regulation of a hormonal signalling pathway in higher plants.

Abscisic acid Arabidopsis (abscisic acid) Hormone signalling Hydrogen peroxide Protein phosphatase 2C

Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • Michael Meinhard
    • 1
  • Pedro L. Rodriguez
    • 1
  • Erwin Grill
    • 1
  1. 1.Lehrstuhl für Botanik, Technische Universität München, Biologikum Weihenstephan, Am Hochanger 4, 85354 Freising, Germany
  2. 2.Present address: Instituto de Biologia Molecular y Celular de Plantas, Universidad Politecnica-C.S.I.C., Camino de Vera, 46022 Valencia, Spain