Dual control of MAPK activities by AP2C1 and MKP1 MAPK phosphatases regulates defence responses in Arabidopsis

Abstract

Mitogen-activated protein kinase (MAPK) cascades transmit environmental signals and induce stress and defence responses in plants. These signalling cascades are negatively controlled by specific phosphatases of the type 2C Ser/Thr protein phosphatase (PP2C) and dual-specificity phosphatase (DSP) families that inactivate stress-induced MAPKs; however, the interplay between phosphatases of these different types has remained unknown. Our work reveals that different Arabidopsis MAPK phosphatases, the PP2C-type AP2C1 and the DSP-type MKP1, exhibit both specific and overlapping functions in plant stress responses. Each single mutant and ap2c1 mkp1 double mutant displayed enhanced stress-induced activation of MAPKs MPK3, MPK4, and MPK6, as well as induction of a set of transcription factors. Moreover, ap2c1 mkp1 double mutants show an autoimmune-like response, associated with elevated levels of the stress hormones salicylic acid and ethylene, and of the phytoalexin camalexin. Interestingly, this phenotype is reduced in ap2c1 mkp1 mpk3 and ap2c1 mkp1 mpk6 triple mutants, suggesting that the autoimmune-like response is due to MAPK misregulation. We conclude that the evolutionarily distant MAPK phosphatases AP2C1 and MKP1 contribute crucially to the tight control of MAPK activities, ensuring appropriately balanced stress signalling and suppression of autoimmune-like responses during plant growth and development.

Genome-Wide Identification and Expression Analysis of MAPK Gene Family in Lettuce (Lactuca sativa L.) and Functional Analysis of LsMAPK4 in High- Temperature-Induced Bolting

“…When MAPKKK is activated by a sensor/receptor it can phosphorylate serine/threonine residues of S/TXXXXXS/T, in which X represents any amino acid, to activate downstream MAPKK, after which MAPKK continues to phosphorylate the conserved threonine and tyrosine residues in the TXY motif downward to activate MAPK [ 3 , 4 , 5 , 6 , 7 , 8 ]. MAPK cascades respond to almost all biological or abiotic stresses [ 9 , 10 , 11 ], such as mechanical damage [ 12 ], high salt [ 13 ], low temperature [ 14 ], drought [ 15 ] and pathogen invasion [ 16 ] and widely participate in the process of plant growth and development [ 17 , 18 ].…”

Functional screening of the Arabidopsis 2C protein phosphatases family identifies PP2C15 as a negative regulator of plant immunity by targeting BRI1‐associated receptor kinase 1

“…In mammals, immune signalling must be initiated at a specific time plants grow better when there is a fine balance between immunity and growth (Belkhadir et al, 2014;Lozano-Durán & Zipfel, 2015). plants (Ayatollahi et al, 2022;Couto et al, 2016;Segonzac et al, 2014;Singh et al, 2016;Tischer et al, 2017).…”

“…By analysing the ability of all RCAR–PP2C combinations to regulate ABA signalling through transient expression in Arabidopsis protoplasts, it was found that the blocking rate of the ABA response by all class A PP2Cs exceeded 90% (Tischer et al., 2017 ). In the class B family, AP2C1 negatively regulates the wound‐induced MAPK signalling pathway (Ayatollahi et al., 2022 ). Members of the class C protein family are involved in cell development (Song et al., 2020 ).…”

Opposite roles of MAPKKK17 and MAPKKK21 against Tetranychus urticae in Arabidopsis

“…The biological implications of these interactions should be demonstrated in vivo . Furthermore, the magnitude and duration of MAP kinase signalling effect depend on their activation by upstream kinases and their inactivation by protein phosphatases ( Schweighofer et al., 2007 ; Bartels et al., 2010 ; Ayatollahi et al., 2022 ).…”