Abstract
Abscisic acid (ABA) regulates vital physiological responses, and a number of events in the ABA signaling cascade remain to be identified. To allow quantitative analysis of genetic signaling mutants, patch-clamp experiments were developed and performed with the previously inaccessible Arabidopsis guard cells from the wild type and ABA-insensitive (abi) mutants. Slow anion channels have been proposed to play a rate-limiting role in ABA-induced stomatal closing. We now directly demonstrate that ABA strongly activates slow anion channels in wild-type guard cells. Furthermore, ABA-induced anion channel activation and stomatal closing were suppressed by protein phosphatase inhibitors. In abi1-1 and abi2-1 mutant guard cells, ABA activation of slow anion channels and ABA-induced stomatal closing were abolished. These impairments in ABA signaling were partially rescued by kinase inhibitors in abi1 but not in abi2 guard cells. These data provide cell biological evidence that the abi2 locus disrupts early ABA signaling, that abi1 and abi2 affect ABA signaling at different steps in the cascade, and that protein kinases act as negative regulators of ABA signaling in Arabidopsis. New models for ABA signaling pathways and roles for abi1, abi2, and protein kinases and phosphatases are discussed.
Full Text
The Full Text of this article is available as a PDF (1.3 MB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Allan A. C., Fricker M. D., Ward J. L., Beale M. H., Trewavas A. J. Two Transduction Pathways Mediate Rapid Effects of Abscisic Acid in Commelina Guard Cells. Plant Cell. 1994 Sep;6(9):1319–1328. doi: 10.1105/tpc.6.9.1319. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Armstrong F., Leung J., Grabov A., Brearley J., Giraudat J., Blatt M. R. Sensitivity to abscisic acid of guard-cell K+ channels is suppressed by abi1-1, a mutant Arabidopsis gene encoding a putative protein phosphatase. Proc Natl Acad Sci U S A. 1995 Oct 10;92(21):9520–9524. doi: 10.1073/pnas.92.21.9520. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Assmann S. M. Signal transduction in guard cells. Annu Rev Cell Biol. 1993;9:345–375. doi: 10.1146/annurev.cb.09.110193.002021. [DOI] [PubMed] [Google Scholar]
- Bertauche N., Leung J., Giraudat J. Protein phosphatase activity of abscisic acid insensitive 1 (ABI1) protein from Arabidopsis thaliana. Eur J Biochem. 1996 Oct 1;241(1):193–200. doi: 10.1111/j.1432-1033.1996.0193t.x. [DOI] [PubMed] [Google Scholar]
- Finkelstein R. R., Somerville C. R. Three Classes of Abscisic Acid (ABA)-Insensitive Mutations of Arabidopsis Define Genes that Control Overlapping Subsets of ABA Responses. Plant Physiol. 1990 Nov;94(3):1172–1179. doi: 10.1104/pp.94.3.1172. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hamill O. P., Marty A., Neher E., Sakmann B., Sigworth F. J. Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch. 1981 Aug;391(2):85–100. doi: 10.1007/BF00656997. [DOI] [PubMed] [Google Scholar]
- Hedrich R., Busch H., Raschke K. Ca2+ and nucleotide dependent regulation of voltage dependent anion channels in the plasma membrane of guard cells. EMBO J. 1990 Dec;9(12):3889–3892. doi: 10.1002/j.1460-2075.1990.tb07608.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kieber J. J., Rothenberg M., Roman G., Feldmann K. A., Ecker J. R. CTR1, a negative regulator of the ethylene response pathway in Arabidopsis, encodes a member of the raf family of protein kinases. Cell. 1993 Feb 12;72(3):427–441. doi: 10.1016/0092-8674(93)90119-b. [DOI] [PubMed] [Google Scholar]
- Kruse T., Tallman G., Zeiger E. Isolation of Guard Cell Protoplasts from Mechanically Prepared Epidermis of Vicia faba Leaves. Plant Physiol. 1989 Aug;90(4):1382–1386. doi: 10.1104/pp.90.4.1382. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lemtiri-Chlieh F., MacRobbie E. A. Role of calcium in the modulation of Vicia guard cell potassium channels by abscisic acid: a patch-clamp study. J Membr Biol. 1994 Jan;137(2):99–107. doi: 10.1007/BF00233479. [DOI] [PubMed] [Google Scholar]
- Leung J., Bouvier-Durand M., Morris P. C., Guerrier D., Chefdor F., Giraudat J. Arabidopsis ABA response gene ABI1: features of a calcium-modulated protein phosphatase. Science. 1994 Jun 3;264(5164):1448–1452. doi: 10.1126/science.7910981. [DOI] [PubMed] [Google Scholar]
- Meyer K., Leube M. P., Grill E. A protein phosphatase 2C involved in ABA signal transduction in Arabidopsis thaliana. Science. 1994 Jun 3;264(5164):1452–1455. doi: 10.1126/science.8197457. [DOI] [PubMed] [Google Scholar]
- Pei Z. M., Ward J. M., Harper J. F., Schroeder J. I. A novel chloride channel in Vicia faba guard cell vacuoles activated by the serine/threonine kinase, CDPK. EMBO J. 1996 Dec 2;15(23):6564–6574. [PMC free article] [PubMed] [Google Scholar]
- Schmidt C., Schelle I., Liao Y. J., Schroeder J. I. Strong regulation of slow anion channels and abscisic acid signaling in guard cells by phosphorylation and dephosphorylation events. Proc Natl Acad Sci U S A. 1995 Oct 10;92(21):9535–9539. doi: 10.1073/pnas.92.21.9535. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schroeder J. I., Hedrich R. Involvement of ion channels and active transport in osmoregulation and signaling of higher plant cells. Trends Biochem Sci. 1989 May;14(5):187–192. doi: 10.1016/0968-0004(89)90272-7. [DOI] [PubMed] [Google Scholar]
- Schroeder J. I., Keller B. U. Two types of anion channel currents in guard cells with distinct voltage regulation. Proc Natl Acad Sci U S A. 1992 Jun 1;89(11):5025–5029. doi: 10.1073/pnas.89.11.5025. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schroeder J. I., Raschke K., Neher E. Voltage dependence of K channels in guard-cell protoplasts. Proc Natl Acad Sci U S A. 1987 Jun;84(12):4108–4112. doi: 10.1073/pnas.84.12.4108. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schroeder J. I., Schmidt C., Sheaffer J. Identification of High-Affinity Slow Anion Channel Blockers and Evidence for Stomatal Regulation by Slow Anion Channels in Guard Cells. Plant Cell. 1993 Dec;5(12):1831–1841. doi: 10.1105/tpc.5.12.1831. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schwartz A., Ilan N., Schwarz M., Scheaffer J., Assmann S. M., Schroeder J. I. Anion-Channel Blockers Inhibit S-Type Anion Channels and Abscisic Acid Responses in Guard Cells. Plant Physiol. 1995 Oct;109(2):651–658. doi: 10.1104/pp.109.2.651. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schwartz A., Wu W. H., Tucker E. B., Assmann S. M. Inhibition of inward K+ channels and stomatal response by abscisic acid: an intracellular locus of phytohormone action. Proc Natl Acad Sci U S A. 1994 Apr 26;91(9):4019–4023. doi: 10.1073/pnas.91.9.4019. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shimazaki K., Kinoshita T., Nishimura M. Involvement of Calmodulin and Calmodulin-Dependent Myosin Light Chain Kinase in Blue Light-Dependent H Pumping by Guard Cell Protoplasts from Vicia faba L. Plant Physiol. 1992 Aug;99(4):1416–1421. doi: 10.1104/pp.99.4.1416. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thiel G., MacRobbie E. A., Blatt M. R. Membrane transport in stomatal guard cells: the importance of voltage control. J Membr Biol. 1992 Feb;126(1):1–18. doi: 10.1007/BF00233456. [DOI] [PubMed] [Google Scholar]
- Thomine S., Zimmermann S., Guern J., Barbier-Brygoo H. ATP-Dependent Regulation of an Anion Channel at the Plasma Membrane of Protoplasts from Epidermal Cells of Arabidopsis Hypocotyls. Plant Cell. 1995 Dec;7(12):2091–2100. doi: 10.1105/tpc.7.12.2091. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ward J. M., Pei Z. M., Schroeder J. I. Roles of Ion Channels in Initiation of Signal Transduction in Higher Plants. Plant Cell. 1995 Jul;7(7):833–844. doi: 10.1105/tpc.7.7.833. [DOI] [PMC free article] [PubMed] [Google Scholar]