A Role for ETR1 in Hydrogen Peroxide Signaling in Stomatal Guard Cells

Abstract

Signaling through the redox active molecule hydrogen peroxide (H 2 O 2 ) is important for several processes in plants, such as stomatal closure, root growth, gravitropism, and responses to pathogen challenge (Neill et al., 2002; Laloi et al., 2004). Although oxidative modification of reactive Cys residues within proteins has been suggested as a means by which H 2 O 2 signaling can activate responses such as gene expression and reversible protein phosphorylation (Cooper et al., 2002; Danon, 2002), the linkage of H 2 O 2 perception to intracellular signaling remains to be elucidated. Here, we report genetic and physiological data that demonstrate a previously uncharacterized function for the Arabidopsis (Arabidopsis thaliana) ethylene receptor ETR1, that of mediating H 2 O 2 signaling in stomatal guard cells. Stomata in the loss-of-function etr1-7 mutant do not close in response to H 2 O 2 , and mutation of a Cys residue in the N-terminal region of ETR1 disrupts H 2 O 2 signaling in both plants and in yeast (Saccharomyces cerevisiae).