title: Functional analysis of chimeric lysin motif domain receptors mediating Nod factor-induced defense signaling in Arabidopsis thaliana and chitin-induced nodulation signaling in Lotus japonicus.
abstract: The expression of chimeric receptors in plants is a way to activate specific signaling pathways by corresponding signal molecules. Defense signaling induced by chitin from pathogens and nodulation signaling of legumes induced by rhizobial Nod factors (NFs) depend on receptors with extracellular lysin motif (LysM) domains. Here, we constructed chimeras by replacing the ectodomain of chitin elicitor receptor kinase 1 (AtCERK1) of Arabidopsis thaliana with ectodomains of NF receptors of Lotus japonicus (LjNFR1 and LjNFR5). The hybrid constructs, named LjNFR1-AtCERK1 and LjNFR5-AtCERK1, were expressed in cerk1-2, an A. thaliana CERK1 mutant lacking chitin-induced defense signaling. When treated with NFs from Rhizobium sp. NGR234, cerk1-2 expressing both chimeras accumulated reactive oxygen species, expressed chitin-responsive defense genes and showed increased resistance to Fusarium oxysporum. In contrast, expression of a single chimera showed no effects. Likewise, the ectodomains of LjNFR1 and LjNFR5 were replaced by those of OsCERK1 (Oryza sativa chitin elicitor receptor kinase 1) and OsCEBiP (O. sativa chitin elicitor-binding protein), respectively. The chimeras, named OsCERK1-LjNFR1 and OsCEBiP-LjNFR5, were expressed in L. japonicus NF receptor mutants (nfr1-1; nfr5-2) carrying a GUS (β-glucuronidase) gene under the control of the NIN (nodule inception) promoter. Upon chitin treatment, GUS activation reflecting nodulation signaling was observed in the roots of NF receptor mutants expressing both chimeras, whereas a single construct was not sufficient for activation. Hence, replacement of ectodomains in LysM domain receptors provides a way to specifically trigger NF-induced defense signaling in non-legumes and chitin-induced nodulation signaling in legumes.
authors: State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat-sen University, East Campus, Guangzhou, 510006, China; Anhui Key Laboratory of Plant Genetics & Breeding, School of Life Sciences, Anhui Agricultural University, 130 Changjiang West Road, Hefei, Anhui, 230036, China.
authors: Wei
authors: W
authors: Wang
authors: Zhi-Ping
authors: ZP
authors: Xie
authors: Christian
authors: C
authors: Staehelin
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002686:Chitin / Q000378:metabolism*; D005670:Fusarium / Q000502:physiology; D017930:Genes, Reporter; D000070116:Lotus / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D009088:Mucoproteins / Q000378:metabolism; D009154:Mutation; D009844:Oligosaccharides / Q000378:metabolism; D012275:Oryza / Q000235:genetics / Q000378:metabolism; D010935:Plant Diseases / Q000276:immunology*; D018515:Plant Leaves / Q000235:genetics / Q000276:immunology / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000235:genetics / Q000276:immunology / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D017382:Reactive Oxygen Species / Q000378:metabolism; D011994:Recombinant Proteins; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D009088:Mucoproteins; D009844:Oligosaccharides; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D011994:Recombinant Proteins; C010393:lysin, gastropoda; D002686:Chitin; C525882:CERK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases
keywords: Arabidopsis thaliana; Lotus japonicus; LysM domain receptor; Nod factors; chimeric receptor; chitin; defense signaling; nodulation signaling