The Arabidopsis outward K+ channel GORK is involved in regulation of stomatal movements and plant transpiration.

E. Hosy, A. Vavasseur, K. Mouline, I. Dreyer, F. Gaymard, F. Poree, J. Boucherez, A. Lebaudy, D. Bouchez, A.-A. Very, T. Simonneau, J.-B. Thibaud, H. Sentenac
Proceedings of the National Academy of Sciences. 2003-04-01; 100(9): 5549-5554
DOI: 10.1073/pnas.0733970100

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1. Proc Natl Acad Sci U S A. 2003 Apr 29;100(9):5549-54. Epub 2003 Apr 1.

The Arabidopsis outward K+ channel GORK is involved in regulation of stomatal
movements and plant transpiration.

Hosy E(1), Vavasseur A, Mouline K, Dreyer I, Gaymard F, Porée F, Boucherez J,
Lebaudy A, Bouchez D, Very AA, Simonneau T, Thibaud JB, Sentenac H.

Author information:
(1)Biochimie et Physiologie Moléculaires des Plantes, Unité Mixte de Recherche
5004, Agro-M/Centre National de la Recherche Scientifique/Institut National de la
Recherche Agronomique/UM2, F-34060 Montpellier Cedex 1, France.

Erratum in
Proc Natl Acad Sci U S A. 2003 Jun 10;100(12):7418.

Comment in
Proc Natl Acad Sci U S A. 2003 Apr 29;100(9):4976-7.

Microscopic pores present in the epidermis of plant aerial organs, called
stomata, allow gas exchanges between the inner photosynthetic tissue and the
atmosphere. Regulation of stomatal aperture, preventing excess transpirational
vapor loss, relies on turgor changes of two highly differentiated epidermal cells
surrounding the pore, the guard cells. Increased guard cell turgor due to
increased solute accumulation results in stomatal opening, whereas decreased
guard cell turgor due to decreased solute accumulation results in stomatal
closing. Here we provide direct evidence, based on reverse genetics approaches,
that the Arabidopsis GORK Shaker gene encodes the major voltage-gated outwardly
rectifying K(+) channel of the guard cell membrane. Expression of GORK dominant
negative mutant polypeptides in transgenic Arabidopsis was found to strongly
reduce outwardly rectifying K(+) channel activity in the guard cell membrane, and
disruption of the GORK gene (T-DNA insertion knockout mutant) fully suppressed
this activity. Bioassays on epidermal peels revealed that disruption of GORK
activity resulted in impaired stomatal closure in response to darkness or the
stress hormone abscisic acid [corrected]. Transpiration measurements on excised
rosettes and intact plants (grown in hydroponic conditions or submitted to water
stress) revealed that absence of GORK activity resulted in increased water
consumption. The whole set of data indicates that GORK is likely to play a
crucial role in adaptation to drought in fluctuating environments.

DOI: 10.1073/pnas.0733970100
PMCID: PMC154382
PMID: 12671068 [Indexed for MEDLINE]

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