Cytoplasmic Alkalization Precedes Reactive Oxygen Species Production during Methyl Jasmonate- and Abscisic Acid-Induced Stomatal Closure

Abstract

(J.M.K.) Signaling events during abscisic acid (ABA) or methyl jasmonate (MJ)-induced stomatal closure were examined in Arabidopsis wild type, ABA-insensitive (ost1-2), and MJ-insensitive mutants ( jar1-1) in order to examine a crosstalk between ABA and MJ signal transduction. Some of the experiments were performed on epidermal strips of Pisum sativum. Stomata of jar1-1 mutant plants are insensitive to MJ but are able to close in response to ABA. However, their sensitivity to ABA is less than that of wildtype plants. Reciprocally, the stomata of ost1-2 are insensitive to ABA but are able to close in response to MJ to a lesser extent compared to wild-type plants. Both MJ and ABA promote H 2 O 2 production in wild-type guard cells, while exogenous application of diphenylene iodonium (DPI) chloride, an inhibitor of NAD(P)H oxidases, results in the suppression of ABA-and MJ-induced stomatal closure. ABA elevates H 2 O 2 production in wild-type and jar1-1 guard cells but not in ost1-2, whereas MJ induces H 2 O 2 production in both wild-type and ost1-2 guard cells, but not in jar1-1. MJ-induced stomatal closing is suppressed in the NAD(P)H oxidase double mutant atrbohD/F and in the outward potassium channel mutant gork1. Furthermore, MJ induces alkalization in guard cell cytosol, and MJ-induced stomatal closing is inhibited by butyrate. Analyses of the kinetics of cytosolic pH changes and reactive oxygen species (ROS) production show that the alkalization of cytoplasm precedes ROS production during the stomatal response to both ABA and MJ. Our results further indicate that JAR1, as OST1, functions upstream of ROS produced by NAD(P)H oxidases and that the cytoplasmic alkalization precedes ROS production during MJ or ABA signal transduction in guard cells.

Sphingosine-1-phosphate (S1P) mediates darkness-induced stomatal closure through raising cytosol pH and hydrogen peroxide (H2O2) levels in guard cells in Vicia faba

“…Although cytosolic alkalization in guard cells has been shown to occur early in ABA-and MJ-induced H 2 O 2 production and stomatal closure [27,61], it is unknown whether cytosolic alkalization is a causal factor for H 2 O 2 production during darkness-induced stomatal closure. To answer this question, the effect of butyric acid on darkness-induced H 2 O 2 production in guard cells was determined.…”

“…Effectors that decrease the cytosolic pH (auxin, fusicoccin) open stomata [28], while those that raise the cytosolic pH (ABA and MJ) result in stomatal closure [27,32]. Cytosolic alkalization has been reported to precede the production of reactive oxygen species during ABA-and MJ-induced stomatal closure [27,61].…”

“…Cytosolic alkalization in guard cells is a common phenomenon in ABA-and MJ-induced stomatal closure in A. thaliana, Pisum sativum, and Paphiopedilum tonsum [27][28][29][30]. ABA elevates the level of cytosolic free Ca 2+ ([Ca 2+ ] cyt ) in accordance with cytosolic alkalization in Paphiopedilum tonsum guard cells [28].…”

“…Intracellular pH changes have long been proposed to function in various physiological processes in plants, such as plant defense responses [20], coleoptile or root hair growth, nodulation, elicitation [2024], and response to hormones such as gibberellic acid, methyl jasmonate (MJ), and ABA [25][26][27]. Cytosolic alkalization in guard cells is a common phenomenon in ABA-and MJ-induced stomatal closure in A. thaliana, Pisum sativum, and Paphiopedilum tonsum [27][28][29][30].…”

Plant Stress Surveillance Monitored by ABA and Disease Signaling Interactions

“…MeJA (methyl jasmonate) treatment induces stomatal closing through a CORONATINE INSENSITIVE1 (COI1)-and JASMO-NATE RESISTANT1 (JAR1)-dependent signaling pathway (Munemasa et al, 2007;Suhita et al, 2004). JA-triggered activation of Stype anion channel and I Ca -channel activities is probably under the control of the same second messengers elicited by ABA because MeJA does not induce stomatal closures in ABA insensitive2-1 (abi2-1) as well as in coi1 (Fig.…”