Decoding MAPK cascades in plant immunity: Activation, regulation, integration, and pathogen manipulation

Mitogen-activated protein kinase (MAPK/MPK) cascades are conserved signaling modules that play crucial roles in plant growth, reproduction, and responses to biotic and abiotic stresses. Many breakthroughs have been made recently in understanding the functional and regulatory mechanisms involving MAPK cascades in plant immunity. In this review, we summarize the conserved composition and activation of MAPK cascades and update advances in understanding the molecular mechanisms by which plants maintain or inhibit MAPK activation. We also highlight the functional links between MAPK activation and other immune events, suggesting crosstalk in the plant immune signaling network. Furthermore, we outline the strategies by which pathogen effectors inhibit plant immunity by manipulating MAPK signaling and illuminate the contribution of MAPK cascades to effector-triggered immunity. Overall, this review provides major evidence for understanding the importance and complexity of MAPK signaling and reveals that the MAPK cascade serves as an essential signaling hub in activating plant immunity.