Protein kinases in the plant defense response

Abstract

Publisher Summary Protein kinases of different families are involved in defense mechanisms at different cellular levels, including elicitor recognition, as extracellular or intracellular receptors, signal transduction, and the induction of transcriptional activation. However, only a few kinases participating in defense signaling have been isolated to date, and their molecular characterization is still very limited. The ability to induce defense mechanisms is a characteristic of incompatible (resistant) plant–pathogen interactions. Resistant plants are equipped with a molecular alert system that allows them not only to recognize pathogen intrusion but also to amplify very efficiently the initial alarm signal and to activate self-defense. Protein kinases and phosphatases in plants, as well as in animals, are implicated as key components in signaling mechanisms critical for responses to environmental stresses and attack by pathogens. The use of protein phosphorylation for signal transduction is particularly suited for defense because it allows efficient amplification of the original signal, negative feedback for desensitization, and cross-talk and branching for the activation of diverse lines of defense. In cellular signal transduction pathways, phosphorylation by protein kinases is antagonized by the dephosphorylation activity of protein phosphatases.