Role of cell wall-associated kinases in plant development and defense responses

Plant life is coordinated by several developmental and defense associated mechanisms and cell wall is actively important in these mechanisms. The plant cell wall also serves as an important component system that monitors plant growth and defense apart from only protecting the cell. However, resident sensors of the plant cell membrane and pattern recognition receptors (PRRs) also constitute major response mechanisms in plants while they are both as well developed for maintaining cell wall integrity (CWI). These PRRs are molecules such as ligands, peptides or glycans that are released for sensing damage collectively refers to as perceived damage associated molecular patterns (DAMPs), or signals for trigger immunity (TI). Pathogen attack frequently promotes the release of DAMPs, thereby activating TI pathways that contribute to disease resistance. The cell-wall associated kinases (WAKs) are of immense importance in this pathway. WAKs are receptor-like proteins which have their own cytoplasmic protein domain cross-linked with pectin fraction in the plant's cell wall. They are generally known to take vital roles in cell expansion process but, it is becoming clearer that they are also involved in plant response to environmental stimuli such as pathogen attack, wounding or abiotic stresses. This review highlights the importance of understanding and identifying wall-monitoring systems involving WAKs, CWI sensors, and trigger immunity-associated PRR-DAMP interactions. This will open a new phase of how we can use these components in boosting plant immune functions and in designing better agricultural strategies such as crop breeding for disease resistance.