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Plant Physiol. 2001 Oct;127(2):473-85.

Dominant negative guard cell K+ channel mutants reduce inward-rectifying K+ currents and light-induced stomatal opening in arabidopsis.

Author information

1
Division of Biology, Cell and Developmental Biology Section, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0116, USA.

Abstract

Inward-rectifying potassium (K+(in)) channels in guard cells have been suggested to provide a pathway for K+ uptake into guard cells during stomatal opening. To test the proposed role of guard cell K+(in) channels in light-induced stomatal opening, transgenic Arabidopsis plants were generated that expressed dominant negative point mutations in the K+(in) channel subunit KAT1. Patch-clamp analyses with transgenic guard cells from independent lines showed that K+(in) current magnitudes were reduced by approximately 75% compared with vector-transformed controls at -180 mV, which resulted in reduction in light-induced stomatal opening by 38% to 45% compared with vector-transformed controls. Analyses of intracellular K+ content using both sodium hexanitrocobaltate (III) and elemental x-ray microanalyses showed that light-induced K+ uptake was also significantly reduced in guard cells of K+(in) channel depressor lines. These findings support the model that K+(in) channels contribute to K+ uptake during light-induced stomatal opening. Furthermore, transpirational water loss from leaves was reduced in the K+(in) channel depressor lines. Comparisons of guard cell K+(in) current magnitudes among four different transgenic lines with different K+(in) current magnitudes show the range of activities of K+(in) channels required for guard cell K+ uptake during light-induced stomatal opening.

PMID:
11598222
PMCID:
PMC125083
[Indexed for MEDLINE]
Free PMC Article

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