Wounding and Insect Feeding Trigger Two Independent MAPK Pathways with Distinct Regulation and Kinetics

Abstract

Wounding induces the parallel activation of two signaling cascades: a MKK4/5-MPK3/6 module (rapid) and a JA-dependent MAP3K14-MKK3-MPK1/2/7/14 module (slow) to restrict insect feeding.

Genome-Wide Identification and Analysis of MKK and MAPK Gene Families in Brassica Species and Response to Stress in Brassica napus

“…In our study, BnaMKK9.1 and BnaMKK9.2 were expressed at high levels in young and mature leaves at the bolting, initial flowering and flowering stages, suggesting possible roles in leaf development. MKK4 and MKK5 were reported to modulate stomatal development [ 56 ], while MKK6 appears to play an important role in meiotic cytokinesis during pollen development [ 31 ]. Here, the putative B. napus orthologs BnaMKK4 , BnaMKK5, and BnaMKK6 were seldom expression in most tissues and developmental stages, supporting the notion that these genes may not regulate growth or development or that any such regulation might occur at the post-transcriptional level.…”

Defense, Fast and Slow: Activation of Different MAPK Pathways in Response to Wounding

“…Although mitogenactivated protein (MAP) kinase cascades, comprised of MAP kinase kinase kinases (MAP3Ks) that phosphorylate MAP kinase kinases (MKKs) that in turn activate MAP kinases (MPKs), are well-known signal transducers in defense against insects (Hettenhausen et al, 2015), the roles of specific MAPK modules in activating wound responses need further study. Here, Sözen et al (2020) show that wounding induces a MAPK signaling module involving little known clade III MAP3Ks, the atypical MKK3 and the clade C MAPKs MPK1, MPK2 and MPK7. This induction is slower than the better studied MPK3/MPK6 pathway, and unlike MPK3/MPK6 activation, is dependent on JA signaling.…”

“…Activation of the MAP3K14-MKK3-MPK1/MPK2/MPK7 cascade through transcriptional regulation of MAP3K14 is JA-dependent and requires the JA receptor COI1. (Modified from Sözen et al [2020], Figure 8).…”

Breaking Bad News: Dynamic Molecular Mechanisms of Wound Response in Plants

“…Downstream of the wound-activated MKK4/MKK5-MPK3/MPK6 cascade and CPK5/CKP6 phosphorylation is the upregulation of ethylene biosynthesis genes and ethylene accumulation ( Li et al, 2018 ). Intriguingly, next to the classical fast activation of MAPK cascades, a later activation controlled by JA-induced MAP3Ks expression and a cascade involving MKK3 phosphorylation of MPK1/2/7 can be observed with a maximum at 1 h after mechanical and herbivore-induced damage ( Ortiz-Masia et al, 2007 ; Sözen et al, 2020 ).…”

“…Wound-induced ethylene accumulation is thought to proceed via transcriptional upregulation of its rate-limiting biosynthetic enzyme 1-aminocyclopropane-l-carboxylate (ACC) synthase (ACS) resulting in a lag-time of 20–30 min before the first accumulation of ethylene and a peak within hours after wounding ( Boller and Kende, 1980 ; Kato et al, 2000 ; Marhavý et al, 2019 ). Ethylene production depends on both ROS and Ca 2+ increases ( Marhavý et al, 2019 ) and is transduced by MAPK and CDPK-dependent phosphorylation for activation of ACS gene expression locally at wound sites ( Wu et al, 2007 ; Li et al, 2018 ; Sözen et al, 2020 ). Possible involvement of DAMPs cannot be ruled out, as Peps induce the accumulation of ethylene within 5 h after exogenous peptide application ( Bartels et al, 2013 ).…”