AUTHOR=Lee Dong Sook , Kim Young Cheon , Kwon Sun Jae , Ryu Choong-Min , Park Ohkmae K. 

TITLE=The Arabidopsis Cysteine-Rich Receptor-Like Kinase CRK36 Regulates Immunity through Interaction with the Cytoplasmic Kinase BIK1

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.01856

DOI=10.3389/fpls.2017.01856

ISSN=1664-462X

ABSTRACT=<p>Receptor-like kinases are important signaling components that regulate a variety of cellular processes. In this study, an Arabidopsis cDNA microarray analysis led to the identification of the cysteine-rich receptor-like kinase CRK36 responsive to the necrotrophic fungal pathogen, <italic>Alternaria brassicicola</italic>. To determine the function of <italic>CRK36</italic> in plant immunity, T-DNA-insertion knockdown (<italic>crk36</italic>) and overexpressing (<italic>CRK36OE</italic>) plants were prepared. <italic>CRK36OE</italic> plants exhibited increased hypersensitive cell death and ROS burst in response to avirulent pathogens. Treatment with a typical pathogen-associated molecular pattern, flg22, markedly induced pattern-triggered immune responses, notably stomatal defense, in <italic>CRK36OE</italic> plants. The immune responses were weakened in <italic>crk36</italic> plants. Protein-protein interaction assays revealed the <italic>in vivo</italic> association of CRK36, FLS2, and BIK1. CRK36 enhanced flg22-triggered BIK1 phosphorylation, which showed defects with Cys mutations in the DUF26 motifs of CRK36. Disruption of <italic>BIK1</italic> and <italic>RbohD/RbohF</italic> genes further impaired CRK36-mediated stomatal defense. We propose that CRK36, together with BIK1 and NADPH oxidases, may form a positive activation loop that enhances ROS burst and leads to the promotion of stomatal immunity.</p>