Dual Activities of Receptor-Like Kinase OsWAKL21.2 Induce Immune Responses.

Plant pathogens secrete cell wall-degrading enzymes that degrade various components of the plant cell wall. Plants sense this cell wall damage as a mark of infection and induce immune responses. However, the plant functions that are involved in the elaboration of cell wall damage-induced immune responses remain poorly understood. Transcriptome analysis revealed that a rice () receptor-like kinase, (), is up-regulated following treatment with either pv (a bacterial pathogen) or lipaseA/esterase (LipA; a cell wall-degrading enzyme of pv ). Overexpression of in rice induces immune responses similar to those activated by LipA treatment. Down-regulation of attenuates LipA-mediated immune responses. Heterologous expression of in Arabidopsis () also activates plant immune responses. OsWAKL21.2 is a dual-activity kinase that has in vitro kinase and guanylate cyclase activities. Interestingly, kinase activity of OsWAKL21.2 is necessary to activate rice immune responses, whereas in Arabidopsis, OsWAKL21.2 guanylate cyclase activity activates these responses. Our study reveals a rice receptor kinase that activates immune responses in two different species via two different mechanisms.