Project description:A LysM Receptor-like Kinase Mediates Chitin Perception and Fungal Resistance in Arabidopsis; Jinrong Wan,1 Xuecheng Zhang,1 David Neece,2 Katrina M. Ramonell,3 Steve Clough,2,4 Sung-yong Kim,1 Minviluz Stacey,1 and Gary Stacey1*; 1Division of Plant Sciences, National Center for Soybean Biotechnology, C.S. Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA; 2Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; 3Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA; 4US Department of Agriculture, Soybean/Maize Germplasm, Pathology and Genetics Research, Urbana, IL 61801, USA; *To whom correspondence should be addressed. E-mail: staceyg@missouri.edu; Abstract: Chitin, a polymer of N-acetyl-D-glucosamine, is found in fungal cell walls, but not in plants. Plant cells are capable of perceiving chitin fragments (chitooligosaccharides) to trigger various defense responses. We identified a LysM receptor-like protein (AtLysM RLK1) that is required for the perception of chitooligosaccharides in Arabidopsis. Mutation of this gene blocked the induction of almost all chitooligosaccharide-responsive genes (CRGs) and led to more susceptibility to fungal pathogens, but not to a bacterial pathogen. In addition, exogenously applied chitooligosaccharides enhanced resistance against both fungal and bacterial pathogens in the wild-type plants, but not in the mutant. Together, our data strongly suggest AtLysM RLK1 is the chitin receptor or a key part of the receptor complex and chitin is a PAMP (pathogen-associated molecular pattern) in fungi recognized by the receptor leading to the induction of plant innate immunity against fungal pathogens. Since LysM RLKs were also recently shown to be critical for the perception of the rhizobial lipo-chitin Nod signals, our data suggest that LysM RLKs not just recognize friendly symbiotic rhizobia (via their lipo-chitin Nod signals), but also hostile fungal pathogens (via their cell wall chitin). These data suggest a possible evolutionary relationship between the perception mechanisms of Nod signals and chitin by plants. Experiment Overall Design: wild type Col-0 and chitin receptor mutants treated with or without chitooctaose
Project description:A LysM Receptor-like Kinase Mediates Chitin Perception and Fungal Resistance in Arabidopsis Jinrong Wan,1 Xuecheng Zhang,1 David Neece,2 Katrina M. Ramonell,3 Steve Clough,2,4 Sung-yong Kim,1 Minviluz Stacey,1 and Gary Stacey1* 1Division of Plant Sciences, National Center for Soybean Biotechnology, C.S. Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA 2Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA 3Department of Biological Sciences, University of Alabama, Tuscaloosa, AL 35487, USA 4US Department of Agriculture, Soybean/Maize Germplasm, Pathology and Genetics Research, Urbana, IL 61801, USA *To whom correspondence should be addressed. E-mail: staceyg@missouri.edu Abstract: Chitin, a polymer of N-acetyl-D-glucosamine, is found in fungal cell walls, but not in plants. Plant cells are capable of perceiving chitin fragments (chitooligosaccharides) to trigger various defense responses. We identified a LysM receptor-like protein (AtLysM RLK1) that is required for the perception of chitooligosaccharides in Arabidopsis. Mutation of this gene blocked the induction of almost all chitooligosaccharide-responsive genes (CRGs) and led to more susceptibility to fungal pathogens, but not to a bacterial pathogen. In addition, exogenously applied chitooligosaccharides enhanced resistance against both fungal and bacterial pathogens in the wild-type plants, but not in the mutant. Together, our data strongly suggest AtLysM RLK1 is the chitin receptor or a key part of the receptor complex and chitin is a PAMP (pathogen-associated molecular pattern) in fungi recognized by the receptor leading to the induction of plant innate immunity against fungal pathogens. Since LysM RLKs were also recently shown to be critical for the perception of the rhizobial lipo-chitin Nod signals, our data suggest that LysM RLKs not just recognize friendly symbiotic rhizobia (via their lipo-chitin Nod signals), but also hostile fungal pathogens (via their cell wall chitin). These data suggest a possible evolutionary relationship between the perception mechanisms of Nod signals and chitin by plants. Keywords: chitooctaose, chitin receptor mutant
Project description:Plant cell surface receptors sense microbial pathogens by recognizing microbial structures called pathogen or microbe-associated molecular patterns (PAMPs/MAMPs). There are two major types of plant pattern recognition receptors: 1. Leucine-rich repeat receptor proteins (LRR-RP) and LRR receptor kinases (LRR-RK) and 2. Plant receptor proteins and receptor kinases carrying ectopic lysin motifs (LysM-RP and LysM-RK). In this study, Arabidopsis thaliana responses to three different MAMPs, flg22, nlp20, chitin (C6), via their corresponding receptor types, FLS2 (LRR-RK), RLP23 (LRR-RP), CERK1 (LysM-RK) were compared. Our RNA-seq results indicate that a core set of defense-related genes can be activated through perception of different MAMPs. However, there are also notable differences in the transcriptional changes in response to the various elicitors; flg22 causes broader transcriptome changes than nlp20 and C6, and C6 does not cause late transcriptome changes.
Project description:Perception of microbe-associated molecular patterns by host cell-surface pattern recognition receptors triggers a series of immune responses such as activation of mitogen-activated protein kinase (MAPK) cascades. In Arabidopsis thaliana, the receptor-like cytoplasmic kinase PBL27 interacts with the chitin receptor CERK1 and regulates chitin-induced MAPK activation. We found that the MAPK kinase kinase MAPKKK5 connects PBL27 to the downstream MAPK Kinases (MKK4/5) and MAPKs (MPK3/6). RNA-seq analysis using the mapkkk5 mutant indicated that MAPKKK5 plays important roles in chitin-induced transcriptional reprogramming. As far as we are aware, this is the first report pointing to the significance of a complete MAPK cascade in defense-associated transcriptional reprogramming in plants.
Project description:Pattern-recognition receptor (PRR)-triggered immunity (PTI) plays a pivotal role in plant immunity to ward off a wide range of pathogenic microbes. The model liverwort Marchantia polymorpha is gaining popularity in investigating the evolution of plant-microbe interactions. The M. polymorpha is capable of triggering defense-related gene expression by sensing components in bacterial and fungal extracts, suggesting existence of PTI in this plant model. However, the molecular components that would form PTI in M. polymorpha have not yet been described. We show that, in M. polymorpha, lysin motif (LysM) receptor-like kinase (LYK) MpLYK1 and LYK-related (LYR) MpLYR, among four LysM receptor homologs, are required for sensing chitin and peptidoglycan (PGN) fragments and thereby triggering a series of immune responses. Phosphoproteomic analysis of M. polymorpha in response to chitin treatment comprehensively identified regulatory proteins that would shape LysM-mediated PTI. The identified proteins covered homologs of well-described PTI components in angiosperms as well as proteins whose roles in PTI are not yet determined including the blue-light receptor phototropin MpPHOT. We revealed that MpPHOT is required for a negative feedback of defense-related gene expression during PTI. Taken together, this study provides the basic framework of LysM-mediated PTI in M. polymorpha and demonstrates the utility of M. polymorpha as a plant model for discovering novel or fundamental molecular mechanisms underlying PRR-triggered immune signaling in plants.
Project description:Pattern-recognition receptor (PRR)-triggered immunity (PTI) plays a pivotal role in plant immunity to ward off a wide range of pathogenic microbes. The model liverwort Marchantia polymorpha is gaining popularity in investigating the evolution of plant-microbe interactions. The M. polymorpha is capable of triggering defense-related gene expression by sensing components in bacterial and fungal extracts, suggesting existence of PTI in this plant model. However, the molecular components that would form PTI in M. polymorpha have not yet been described. We show that, in M. polymorpha, lysin motif (LysM) receptor-like kinase (LYK) MpLYK1 and LYK-related (LYR) MpLYR, among four LysM receptor homologs, are required for sensing chitin and peptidoglycan (PGN) fragments and thereby triggering a series of immune responses. Phosphoproteomic analysis of M. polymorpha in response to chitin treatment comprehensively identified regulatory proteins that would shape LysM-mediated PTI. The identified proteins covered homologs of well-described PTI components in angiosperms as well as proteins whose roles in PTI are not yet determined including the blue-light receptor phototropin MpPHOT. We revealed that MpPHOT is required for a negative feedback of defense-related gene expression during PTI. Taken together, this study provides the basic framework of LysM-mediated PTI in M. polymorpha and demonstrates the utility of M. polymorpha as a plant model for discovering novel or fundamental molecular mechanisms underlying PRR-triggered immune signaling in plants.
Project description:Pattern-recognition receptor (PRR)-triggered immunity (PTI) plays a pivotal role in plant immunity to ward off a wide range of pathogenic microbes. The model liverwort Marchantia polymorpha is gaining popularity in investigating the evolution of plant-microbe interactions. The M. polymorpha is capable of triggering defense-related gene expression by sensing components in bacterial and fungal extracts, suggesting existence of PTI in this plant model. However, the molecular components that would form PTI in M. polymorpha have not yet been described. We show that, in M. polymorpha, lysin motif (LysM) receptor-like kinase (LYK) MpLYK1 and LYK-related (LYR) MpLYR, among four LysM receptor homologs, are required for sensing chitin and peptidoglycan (PGN) fragments and thereby triggering a series of immune responses. Phosphoproteomic analysis of M. polymorpha in response to chitin treatment comprehensively identified regulatory proteins that would shape LysM-mediated PTI. The identified proteins covered homologs of well-described PTI components in angiosperms as well as proteins whose roles in PTI are not yet determined including the blue-light receptor phototropin MpPHOT. We revealed that MpPHOT is required for a negative feedback of defense-related gene expression during PTI. Taken together, this study provides the basic framework of LysM-mediated PTI in M. polymorpha and demonstrates the utility of M. polymorpha as a plant model for discovering novel or fundamental molecular mechanisms underlying PRR-triggered immune signaling in plants.
Project description:Chitin, a polymer of N-acetyl-glucosamne, is a component of the cell walls of many plant fungal pathogens. During the infection process, the released chitin fragments (such as chitooctaose) from fungal cell walls by plant enzymes can trigger plant defense response and gene activation. The current work studies the regulation of Arabidopsis genes by the purified chitin fragment chitooctaose. We used the Affymetric Arabidopsis whole gene arrays to study the gene expression caused by chitin (chitooctaose). Keywords: chitooctaose vs water treatments, with 3 biological replicates