title: LIK1, a CERK1-interacting kinase, regulates plant immune responses in Arabidopsis.
abstract: Chitin, an integral component of the fungal cell wall, is one of the best-studied microbe-associated molecular patterns. Previous work identified a LysM receptor-like kinase (LysM-RLK1/CERK1) as the primary chitin receptor in Arabidopsis. In order to identify proteins that interact with CERK1, we conducted a yeast two-hybrid screen using the intracellular kinase domain of CERK1 as the bait. This screen identified 54 putative CERK1-interactors. Screening mutants defective in 43 of these interacting proteins identified only two, a calmodulin like protein (At3g10190) and a leucine-rich repeat receptor like kinase (At3g14840), which differed in their response to pathogen challenge. In the present work, we focused on characterizing the LRR-RLK gene where mutations altered responses to chitin elicitation. This LRR-RLK was named LysM RLK1-interacting kinase 1 (LIK1). The interaction between CERK1 and LIK1 was confirmed by co-immunoprecipitation using protoplasts and transgenic plants. In vitro experiments showed that LIK1 was directly phosphorylated by CERK1. In vivo phosphorylation assays showed that Col-0 wild-type plants have more phosphorylated LIK1 than cerk1 mutant plants, suggesting that LIK1 may be directly phosphorylated by CERK1. Lik1 mutant plants showed an enhanced response to both chitin and flagellin elicitors. In comparison to the wild-type plants, lik1 mutant plants were more resistant to the hemibiotrophic pathogen Pseudomonas syringae, but more susceptible to the necrotrophic pathogen Sclerotinia sclerotiorum. Consistent with the enhanced susceptibility to necrotrophs, lik1 mutants showed reduced expression of genes involved in jasmonic acid and ethylene signaling pathways. These data suggest that LIK1 directly interacts with CERK1 and regulates MAMP-triggered innate immunity.
authors.affiliation: Divisions of Plant Sciences and Biochemistry, National Center for Soybean Biotechnology, C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America.
authors.forename: Mi Ha
authors.initials: MH
authors.lastname: Le
authors.affiliation: Divisions of Plant Sciences and Biochemistry, National Center for Soybean Biotechnology, C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America.
authors.forename: Yangrong
authors.initials: Y
authors.lastname: Cao
authors.affiliation: Divisions of Plant Sciences and Biochemistry, National Center for Soybean Biotechnology, C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America.
authors.forename: Xue-Cheng
authors.initials: XC
authors.lastname: Zhang
authors.affiliation: Divisions of Plant Sciences and Biochemistry, National Center for Soybean Biotechnology, C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, United States of America.
authors.forename: Gary
authors.initials: G
authors.lastname: Stacey
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001203:Ascomycota / Q000502:physiology; D002686:Chitin / Q000494:pharmacology; D005408:Flagellin / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D009154:Mutation; D010766:Phosphorylation / Q000187:drug effects; D057865:Plant Immunity / Q000187:drug effects / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D044224:Pseudomonas syringae / Q000502:physiology; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013045:Species Specificity; D020798:Two-Hybrid System Techniques
chemical_list: D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D005408:Flagellin; D002686:Chitin; C000596013:LIK1 protein, Arabidopsis; D011494:Protein Kinases; C525882:CERK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases