Volume 11, No 3, Sep 2001

ISSN: 1001-0602 
EISSN: 1748-7838 2018 
impact factor 17.848* 
(Clarivate Analytics, 2019)

Volume 11 Issue 3, September 2001: 195-202

ORIGINAL ARTICLES

K⁺channels inhibited by hydrogen peroxide mediate abscisic acid signaling in Vicia guard cells

ZHANG Xiao^{1, 2, *}, Yu Chen MIAO², Guo Yong AN², Yun ZHOU², Zhou Ping SHANGGUAN³, Jun Feng GAO¹, Chun Peng SONG^{2, *}

¹College of life sciences, Northwest Sci-Tech University of Agriculture and Forestry, Yangling 712100, China
²Department of Biology, Henan University, Kaifeng 475001, China
³National Laboratory of Soil Erosion and Dryland Farming, the Institute of Soil and Water Conservation, Chinese Academy of Sciences, Yangling 712100, China Correspondence:

A number of
studies show that environmental stress conditions increase abscisic acid (ABA)
and hydrogen peroxide (H₂O₂) levels in plant cells.
Despite this central role of ABA in altering stomatal aperture by regulating
guard cell ion transport, little is known concerning the relationship between
ABA and H₂O₂ in signal transduction leading to stomatal
movement. Epidermal strip bioassay illustrated that ABA-inhibited stomatal
opening and ABA-induced stomatal closure were abolished partly by externally
added catalase (CAT) or diphenylene iodonium (DPI), which are a H₂O₂
scavenger and a NADPH oxidase inhibitor respectively. In contrast, internally
added CAT or DPI nearly completely or partly reversed ABA-induced closure in
half-stoma. Consistent with these results, whole-cell patch-clamp analysis
showed that intracellular application of CAT or DPI partly abolished
ABA-inhibited inward K⁺ current across the plasma membrane of guard
cells. H₂O₂ mimicked ABA to inhibit inward K⁺
current, an effect which was reversed by the addition of ascorbic acid (V_c)
in patch clamping micropipettes. These results suggested that H₂O₂
mediated ABA-induced stomatal movement by targeting inward K⁺
channels at plasma membrane.

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