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The mitogen-activated protein kinase (MAPK) cascades act as crucial signaling modules that regulate plant growth and development, response to biotic/abiotic stresses, and plant immunity. MAP3Ks can be activated through MAP4K phosphorylation in non-plant systems, but this has not been reported in plants to date. Here, we identified a total of 234 putative TaMAPK family members in wheat (Triticum aestivum L.). They included 48 MAPKs, 17 MAP2Ks, 144 MAP3Ks, and 25 MAP4Ks. We conducted systematic analyses of the evolution, domain conservation, interaction networks, and expression profiles of these TaMAPK–TaMAP4K (representing TaMAPK, TaMAP2K, TaMAP3K, and TaMAP4K) kinase family members. The 234 TaMAPK–TaMAP4Ks are distributed on 21 chromosomes and one unknown linkage group (Un). Notably, 25 of these TaMAP4K family members possessed the conserved motifs of MAP4K genes, including glycine-rich motif, invariant lysine (K) motif, HRD motif, DFG motif, and signature motif. TaMAPK3 and 6, and TaMAP4K10/24 were shown to be strongly expressed not only throughout the growth and development stages but also in response to drought or heat stress. The bioinformatics analyses and qRT-PCR results suggested that wheat may activate the MAP4K10–MEKK7–MAP2K11–MAPK6 pathway to increase drought resistance in wheat, and the MAP4K10–MAP3K8–MAP2K1/11-MAPK3 pathway may be involved in plant growth. In general, our work identified members of the MAPK–MAP4K cascade in wheat and profiled their potential roles during their response to abiotic stresses and plant growth based on their expression pattern. The characterized cascades might be good candidates for future crop improvement and molecular breeding.

Mitogen-activated protein kinases (MAPKs) form tightly controlled signaling cascades that play essential roles in plant growth, development, and defense response. However, the molecular mechanisms underlying MAPK cascades are still very elusive, largely because of our poor understanding of how they relay the signals. The MAPK cascade is composed of MAPK, MAPKK, and MAPKKK. They transfer signals through the phosphorylation of MAPKKK, MAPKK, and MAPK in turn. MAPKs are organized into a complex network for efficient transmission of specific stimuli. This review summarizes the research progress in recent years on the classification and functions of MAPK cascades under various conditions in plants, especially the research status and general methods available for identifying MAPK substrates, and provides suggestions for future research directions.

The mitogen-activated protein kinase (MAPK) cascades act as crucial signaling modules that regulate plant growth and development, response to biotic/abiotic stresses, and plant immunity. MAP3Ks can be activated through MAP4K phosphorylation in non-plant systems, but this has not been reported in plants to date. Here, we identified a total of 234 putative TaMAPK family members in wheat ( Triticum aestivum L.). They included 48 MAPKs , 17 MAP2Ks , 144 MAP3Ks , and 25 MAP4Ks . We conducted systematic analyses of the evolution, domain conservation, interaction networks, and expression profiles of these TaMAPK-TaMAP4K (representing TaMAPK , TaMAP2K , TaMAP3K , and TaMAP4K ) kinase family members. The 234 TaMAPK-TaMAP4K s are distributed on 21 chromosomes and one unknown linkage group (Un). Notably, 25 of these TaMAP4K family members possessed the conserved motifs of MAP4K genes, including glycine-rich motif, invariant lysine (K) motif, HRD motif, DFG motif, and signature motif. TaMAPK3 and 6 , and TaMAP4K10 / 24 were shown to be strongly expressed not only throughout the growth and development stages but also in response to drought or heat stress. The bioinformatics analyses and qRT-PCR results suggested that wheat may activate the MAP4K10-MEKK7-MAP2K11-MAPK6 pathway to increase drought resistance in wheat, and the MAP4K10-MAP3K8-MAP2K1/11-MAPK3 pathway may be involved in plant growth. In general, our work identified members of the MAPK-MAP4K cascade in wheat and profiled their potential roles during their response to abiotic stresses and plant growth based on their expression pattern. The characterized cascades might be good candidates for future crop improvement and molecular breeding.

The objective of this study was to determine the effect of six chlorogenic acid (CGA) isomers known to be present in coffee and other plant foods on modulating the inflammatory response induced by pro-inflammatory cytokines in the Caco-2 human intestinal epithelial cell line. Compared to caffeoylquinic acids (CQA), dicaffeoylquinic acids (DiCQA) had significantly stronger (p < 0.05) capacities to reduce phosphorylation of one of mitogen-activated protein kinases (MAPK) cascades, namely p38. Compared to the control, CQA isomers treatment resulted in around 50% reduction in an interleukin-8 (IL-8) secretion, whereas DiCQA, at the same concentration, resulted in a 90% reduction in IL-8 secretion, compared to the control cells. CGA isomer treatment also showed a significant effect (p < 0.05) on the up-regulation of NFκB subunit p65 nuclear translocation by more than 1.5 times, compared to the control. We concluded that CGA isomers exert anti-inflammatory activity in a mixture of interferon gamma (IFNγ) and phorbol myristate acetate (PMA)-challenged Caco-2 cells, by decreasing the phosphorylation of p38 cascade and up-regulating NFκB signaling.

Exposure of plants to toxic concentrations of metals leads to disruption of the cellular redox status followed by an accumulation of reactive oxygen species (ROS). ROS, like hydrogen peroxide, can act as signaling molecules in the cell and induce signaling via mitogen-activated protein kinase (MAPK) cascades. MAPK cascades are evolutionary conserved signal transduction modules, able to convert extracellular signals to appropriate cellular responses. In this review, our current understanding about MAPK signaling in plant metal stress is discussed. However, this knowledge is scarce compared to research into the role of MAPK signaling in the case of other abiotic and biotic stresses. ROS production is a common response induced by different stresses and undiscovered analogies may exist with metal stress. Therefore, further attention is given to MAPK signaling in other biotic and abiotic stresses and its interplay with other signaling pathways to create a framework in which the involvement of MAPK signaling in metal stress may be studied.