Autophosphorylation of Specific Threonine and Tyrosine Residues in Arabidopsis CERK1 is Essential for the Activation of Chitin-Induced Immune Signaling.

Pattern recognition receptors on the plant cell surface mediate the recognition of microbe/damage-associated molecular patterns (MAMPs/DAMPs) and activate downstream immune signaling. Autophosphorylation of signaling receptor-like kinases is a critical event for the activation of downstream responses but the function of each phosphorylation site in the regulation of immune signaling is not well understood. In this study, 41 Ser/Thr/Tyr and 15 Ser/Thr residues were identified as in vitro and in vivo autophosphorylation sites of Arabidopsis CERK1, which is essential for chitin signaling.

Presence of LYM2 dependent but CERK1 independent disease resistance in Arabidopsis.

Plants have the ability to detect invading fungi through the perception of chitin fragments released from the fungal cell walls. Plant chitin receptor consists of two types of plasma membrane proteins, CEBiP and CERK1. However, the contribution of these proteins to chitin signaling is different between Arabidopsis and rice.

Functional characterization of CEBiP and CERK1 homologs in arabidopsis and rice reveals the presence of different chitin receptor systems in plants.

Chitin is a representative microbe-associated molecular pattern (MAMP) molecule for various fungi and induces immune responses in many plant species. It has been clarified that the chitin signaling in rice requires a receptor kinase OsCERK1 and a receptor-like protein (Os)CEBiP, which specifically binds chitin oligosaccharides. On the other hand, Arabidopsis requires a receptor kinase (At)CERK1 for chitin signaling but it is not clear whether the plant also requires a CEBiP-like molecule for chitin perception/signaling.