Two guard cell mitogen‐activated protein kinases, MPK9 and MPK12, function in methyl jasmonate‐induced stomatal closure in Arabidopsis thaliana

Abstract

Methyl jasmonate (MeJA) and abscisic acid (ABA) signalling cascades share several signalling components in guard cells. We previously showed that two guard cell-preferential mitogen-activated protein kinases (MAPKs), MPK9 and MPK12, positively regulate ABA signalling in Arabidopsis thaliana. In this study, we examined whether these two MAP kinases function in MeJA signalling using genetic mutants for MPK9 and MPK12 combined with a pharmacological approach. MeJA induced stomatal closure in mpk9-1 and mpk12-1 single mutants as well as wild-type plants, but not in mpk9-1 mpk12-1 double mutants. Consistently, the MAPKK inhibitor PD98059 inhibited the MeJA-induced stomatal closure in wild-type plants. MeJA elicited reactive oxygen species (ROS) production and cytosolic alkalisation in guard cells of the mpk9-1, mpk12-1 and mpk9-1 mpk12-1 mutants, as well in wild-type plants. Furthermore, MeJA triggered elevation of cytosolic Ca(2+) concentration ([Ca(2+)]cyt ) in the mpk9-1 mpk12-1 double mutant as well as wild-type plants. Activation of S-type anion channels by MeJA was impaired in mpk9-1 mpk12-1. Together, these results indicate that MPK9 and MPK12 function upstream of S-type anion channel activation and downstream of ROS production, cytosolic alkalisation and [Ca(2+)]cyt elevation in guard cell MeJA signalling, suggesting that MPK9 and MPK12 are key regulators mediating both ABA and MeJA signalling in guard cells.

Jasmonate‐mediated stomatal closure under elevated CO2 revealed by time‐resolved metabolomics

“…Changes in lipid metabolites included isoprenoids, sterols, alpha‐linoleates and fatty acids (Figure S2: Clusters 1: six increased; Clusters 2: 11 increased; while Clusters 7: eight decreased). Among these lipid metabolites, JAs are a very intriguing group as JAs are known to induce stomatal closure in many studies (Zhu et al ., ; Munemasa et al ., ; Khokon et al ., ). The biosynthesis of JA starts with the oxidation of alpha‐linolenic acid to 13(S)‐hydroperoxylinolenic acid in the chloroplast membrane.…”

A review of redox signaling and the control of MAP kinase pathway in plants

“…It is reported that the AtMPK9 and AtMPK12 act redundantly as positive regulators of ROS-mediated stomatal closure in response to ABA [159], yeast elicitor [160], or methyl jasmonate [161]. However, AtMPK9 and AtMPK12 may act via a different mechanism in stomata.…”

Arabidopsis MAP3K16 and Other Salt-Inducible MAP3Ks Regulate ABA Response Redundantly

“…The MKK1-MPK6 module mediates ABA response during seed germination by regulating CAT1 expression and glucose-induced ABA level (Xing et al, 2008; 2009). MPK9 and MPK12 positively regulate both ABA- and MeJA-dependent guard cell signaling (Jammes et al, 2009; Khokon et al, 2015). Additionally, a large number of MAPKs in Arabidopsis and other plant species are known to be induced or activated by ABA and abiotic stresses (Danquah et al, 2014).…”