scholarly journals Both transient and sustained MPK3/6 activities positively control expression of NLR genes in PTI and ETI.

2021 ◽  
Author(s):  
Julien Lang ◽  
Genot Baptiste ◽  
Jean Bigeard ◽  
Jean Colcombet
Keyword(s):  
Plant Immunity ◽  
Active Form ◽  
Leucine Rich Repeat ◽  
Nucleotide Binding Domain ◽  
Activation Kinetics ◽  
Mitogen Activated Protein Kinases ◽  
Functional Differences ◽  
Mitogen Activated Protein ◽  
Effector Triggered Immunity ◽  
Insight Into

Arabidopsis thaliana Mitogen Activated Protein Kinases 3 and 6 (MPK3/6) are known to be activated transiently in PAMP-Triggered Immunity (PTI) and durably in Effector-Triggered Immunity (ETI). However the functional differences between these two kinds of activation kinetics and how they allow coordination of the two layers of plant immunity remain poorly understood. Here, by analysing suppressors of the phenotype caused by a constitutively active form of MPK3, we demonstrate that ETI-mediating nucleotide-binding domain leucine-rich repeat receptors (NLRs) and NLR signaling can act downstream of MPK3 activities. Moreover we provide evidence that both sustained and transient MPK3/6 activities positively control the expression of at least two NLR genes, AT3G04220 and AT4G1110. We further show that the ETI regulators NDR1 and EDS1 also contribute to the upregulations of these two NLRs not only in an ETI context but also in a PTI context. Remarkably, while in ETI, MPK3/6 activities are dependent on NDR1 and EDS1, they are not in PTI, suggesting that if the same actors are involved in the two layers of immunity, the way they are interconnected is different. Finally we demonstrate that expression of the NLR AT3G04220 is sufficient to induce expression of defense genes from the SA branch. Overall this study enlarges our knowledge of MPK3/6 functions during immunity and gives a new insight into the intrication of PTI and ETI.

scholarly journals Estradiol-inducible AvrRps4 expression reveals distinct properties of TIR-NLR-mediated effector-triggered immunity

2020 ◽  
Vol 71 (6) ◽  
pp. 2186-2197 ◽  
Author(s):  
Bruno Pok Man Ngou ◽  
Hee-Kyung Ahn ◽  
Pingtao Ding ◽  
Amey Redkar ◽  
Hannah Brown ◽  
...  
Keyword(s):  
Cell Death ◽  
Cell Surface Receptor ◽  
Leucine Rich Repeat ◽  
Nucleotide Binding Domain ◽  
Hypersensitive Cell Death ◽  
Cell Death Response ◽  
Defence Genes ◽  
Surface Receptor ◽  
Effector Triggered Immunity ◽  
Bacterial Effectors

Abstract Plant nucleotide-binding domain, leucine-rich repeat receptor (NLR) proteins play important roles in recognition of pathogen-derived effectors. However, the mechanism by which plant NLRs activate immunity is still largely unknown. The paired Arabidopsis NLRs RRS1-R and RPS4, that confer recognition of bacterial effectors AvrRps4 and PopP2, are well studied, but how the RRS1/RPS4 complex activates early immediate downstream responses upon effector detection is still poorly understood. To study RRS1/RPS4 responses without the influence of cell surface receptor immune pathways, we generated an Arabidopsis line with inducible expression of the effector AvrRps4. Induction does not lead to hypersensitive cell death response (HR) but can induce electrolyte leakage, which often correlates with plant cell death. Activation of RRS1 and RPS4 without pathogens cannot activate mitogen-associated protein kinase cascades, but still activates up-regulation of defence genes, and therefore resistance against bacteria.

scholarly journals Intimate Association of PRR- and NLR-Mediated Signaling in Plant Immunity

2020 ◽  
pp. MPMI-08-20-0239 ◽  
Author(s):  
You Lu ◽  
Kenichi Tsuda
Keyword(s):  
Immune Response ◽  
Pattern Recognition ◽  
Open Access ◽  
Plant Immunity ◽  
Leucine Rich Repeat ◽  
Nucleotide Binding Domain ◽  
Intimate Association ◽  
Key Topics ◽  
Temporal And Spatial ◽  
Open Access Article

Plants recognize the presence or invasion of microbes through cell surface-localized pattern recognition receptors (PRRs) and intracellular nucleotide-binding domain leucine-rich repeat receptors (NLRs). Although PRRs and NLRs are activated by ligands located in different subcellular compartments through distinct mechanisms, signals initiated from PRRs and NLRs converge into several common signaling pathways with different dynamics. Increasing evidence suggests that PRR- and NLR-mediated signaling extensively crosstalk and such interaction can greatly influence immune response outcomes. Sophisticated experimental setups enabled dissection of the signaling events downstream of PRRs and NLRs with fine temporal and spatial resolution; however, the molecular links underlying the observed interactions in PRR and NLR signaling remain to be elucidated. In this review, we summarize the latest knowledge about activation and signaling mediated by PRRs and NLRs, deconvolute the intimate association between PRR- and NLR-mediated signaling, and propose hypotheses to guide further research on key topics. [Formula: see text] Copyright © 2020 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Receptors in the induction of the plant innate immunity

2021 ◽  
Author(s):  
Tian-Ying Yu ◽  
Meng-Kun Sun ◽  
Li-Kun Liang
Keyword(s):  
Immune Responses ◽  
Innate Immune System ◽  
Effector Proteins ◽  
Innate Immune ◽  
Leucine Rich Repeat ◽  
Nucleotide Binding Domain ◽  
Effector Triggered Immunity ◽  
Growth Development ◽  
Immune Pathway ◽  
Molecular Patterns

Plants adjust amplitude and duration of immune responses via different strategies to maintain growth, development and resistance to pathogens. Pathogen-associated molecular patterns (PAMPs)-triggered immunity (PTI) and effector-triggered immunity (ETI) play vital roles. PRRs (pattern recognition receptors), comprising a large number of receptor-like protein kinases (RLKs) and receptor-like proteins (RLPs), recognize related ligands and trigger immunity. PTI is the first layer of the innate immune system, and it recognizes PAMPs at plasma membrane to prevent infection. However, pathogens exploit effector proteins to bypass or directly inhibit the PTI immune pathway. Consistently, plants have evolved intracellular nucleotide-binding domain and leucine-rich repeat-containing (NLR) proteins to detect pathogenic effectors and trigger a hypersensitive response to activate ETI. PTI and ETI work together to protect plants from infection of virus and other pathogens. Diverse receptors and the corresponding ligands, especially several pairs of well-studied receptors and ligands in PTI immunity, are reviewed to illustrate the dynamic process of PTI response here.

Regulatory role of receptor-like cytoplasmic kinases in early immune signaling events in plants

2020 ◽  
Vol 44 (6) ◽  
pp. 845-856 ◽  
Author(s):  
Lifan Sun ◽  
Jie Zhang
Keyword(s):  
Calcium Influx ◽  
Research Progress ◽  
Oxygen Species ◽  
Nucleotide Binding Domain ◽  
Immune Signaling ◽  
Signaling Events ◽  
Mitogen Activated Protein ◽  
Effector Triggered Immunity ◽  
Molecular Patterns

ABSTRACT Receptor-like cytoplasmic kinases (RLCKs) play crucial roles in regulating plant development and immunity. Conserved pathogen-associated molecular patterns (PAMPs) derived from microbes are recognized by plant pattern recognition receptors to activate PAMP-triggered immunity (PTI). Microbial effectors, whose initial function is to promote virulence, are recognized by plant intracellular nucleotide-binding domain and leucine-rich repeat receptors (NLRs) to initiate effector-triggered immunity (ETI). Both PTI and ETI trigger early immune signaling events including the production of reactive oxygen species, induction of calcium influx and activation of mitogen-activated protein kinases. Research progress has revealed the important roles of RLCKs in the regulation of early PTI signaling. Accordingly, RLCKs are often targeted by microbial effectors that are evolved to evade PTI via diverse modulations. In some cases, modulation of RLCKs by microbial effectors triggers the activation of NLRs. This review covers the mechanisms by which RLCKs engage diverse substrates to regulate early PTI signaling and the regulatory roles of RLCKs in triggering NLR activation. Accumulating evidence suggests evolutionary links and close connections between PAMP- and effector-triggered early immune signaling that are mediated by RLCKs. As key immune regulators, RLCKs can be considered targets with broad prospects for the improvement of plant resistance via genetic engineering.

scholarly journals Mitogen activated protein kinases function as a cohort during a plant defense response

2018 ◽  
Author(s):  
Brant T. McNeece ◽  
Keshav Sharma ◽  
Gary W. Lawrence ◽  
Kathy S. Lawrence ◽  
Vincent P. Klink
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Protein Kinases ◽  
Defense Response ◽  
Defense Genes ◽  
Root Cells ◽  
Mitogen Activated Protein Kinases ◽  
Molecular Pattern ◽  
Mitogen Activated Protein ◽  
Effector Triggered Immunity

ABSTRACTMitogen activated protein kinases (MAPKs) play important signal transduction roles. However, little is known regarding whether MAPKs influence the gene expression of other family members and the relationship that expression has to a biological process. Transcriptomic studies have identified MAPK gene expression occurring within root cells undergoing a defense response to a pathogenic event in the allotetraploidGlycine max. Furthermore, functional analyses are presented for its 32 MAPKs revealing 9 of the 32 MAPKs have a defense role, including homologs ofArabidopsis thalianaMAPK (MPK) MPK2, MPK3, MPK4, MPK5, MPK6, MPK13, MPK16 and MPK20. Defense signal transduction processes occurring through pathogen activated molecular pattern (PAMP) triggered immunity (PTI) and effector triggered immunity (ETI) have been determined in relation to these MAPKs. PTI has been analyzed by examiningBOTRYTIS INDUCED KINASE1(BIK1),ENHANCED DISEASE SUSCEPTIBILITY1(EDS1) andLESION SIMULATING DISEASE1(LSD1). ETI has been analyzed by examining the role of the bacterial effector protein harpin and the downstream cell membrane receptorNON-RACE SPECIFIC DISEASE RESISTANCE1(NDR1). Experiments have identified 5 different types of gene expression relating to MAPK expression. The MAPKs are shown to influence PTI and ETI gene expression and a panel of proven defense genes including an ABC-G type transporter, 20S membrane fusion particle components, glycoside biosynthesis, carbon metabolism, hemicellulose modification, transcription andPATHOGENESIS RELATED 1(PR1). The experiments show MAPKs broadly influence the expression of other defense MAPKs, including the co-regulation of parologous MAPKs and reveal its relationship to proven defense genes.

Reconstitution and structure of a plant NLR resistosome conferring immunity

Science ◽  
2019 ◽  
Vol 364 (6435) ◽  
pp. eaav5870 ◽  
Author(s):  
Jizong Wang ◽  
Meijuan Hu ◽  
Jia Wang ◽  
Jinfeng Qi ◽  
Zhifu Han ◽  
...  
Keyword(s):  
Plant Immunity ◽  
Coiled Coil ◽  
Nucleotide Binding ◽  
Leucine Rich Repeat ◽  
Nucleotide Binding Domain ◽  
Winged Helix ◽  
Pathogen Effectors ◽  
Cryo Electron Microscopy ◽  
Biochemical Mechanisms ◽  
Α Helix

Nucleotide-binding, leucine-rich repeat receptors (NLRs) perceive pathogen effectors to trigger plant immunity. Biochemical mechanisms underlying plant NLR activation have until now remained poorly understood. We reconstituted an active complex containing the Arabidopsis coiled-coil NLR ZAR1, the pseudokinase RKS1, uridylated protein kinase PBL2, and 2′-deoxyadenosine 5′-triphosphate (dATP), demonstrating the oligomerization of the complex during immune activation. The cryo–electron microscopy structure reveals a wheel-like pentameric ZAR1 resistosome. Besides the nucleotide-binding domain, the coiled-coil domain of ZAR1 also contributes to resistosome pentamerization by forming an α-helical barrel that interacts with the leucine-rich repeat and winged-helix domains. Structural remodeling and fold switching during activation release the very N-terminal amphipathic α helix of ZAR1 to form a funnel-shaped structure that is required for the plasma membrane association, cell death triggering, and disease resistance, offering clues to the biochemical function of a plant resistosome.

scholarly journals A bacterial effector protein prevents MAPK-mediated phosphorylation of SGT1 to suppress plant immunity

2019 ◽  
Author(s):  
Gang Yu ◽  
Liu Xian ◽  
Hao Xue ◽  
Wenjia Yu ◽  
Jose S. Rufian ◽  
...  
Keyword(s):  
Immune Responses ◽  
Feedback Loop ◽  
Map Kinases ◽  
Plant Immunity ◽  
Effector Protein ◽  
Leucine Rich Repeat ◽  
Nucleotide Binding Domain ◽  
Mapk Activation ◽  
Positive Feedback Loop ◽  
Shed Light

AbstractNucleotide-binding domain and leucine-rich repeat-containing (NLR) proteins function as sensors that perceive pathogen molecules and activate immunity. In plants, the accumulation and activation of NLRs is regulated by SUPPRESSOR OF G2 ALLELE OF skp1 (SGT1). In this work, we found that an effector protein named RipAC, secreted by the plant pathogen Ralstonia solanacearum, associates with SGT1 to suppress NLR-mediated SGT1-dependent immune responses, including those triggered by another R. solanacearum effector, RipE1. RipAC does not affect the accumulation of SGT1 or NLRs, or their interaction. However, RipAC inhibits the interaction between SGT1 and MAP kinases, and the phosphorylation of a MAPK target motif in the C-terminal domain of SGT1. Such phosphorylation is enhanced upon activation of immune signaling, leads to the release of the interaction between SGT1 and NLRs, and contributes to the activation of NLR-mediated responses. Additionally, SGT1 phosphorylation contributes to resistance against R. solanacearum, and this is particularly evident in the absence of RipAC. Our results shed light onto the mechanism of activation of NLR-mediated immunity, and suggest a positive feedback loop between MAPK activation and SGT1-dependent NLR activation.

Copper–oxygen Dynamics in Tyrosinase

2019 ◽  
Author(s):  
Nobutaka Fujieda ◽  
Sachiko Yanagisawa ◽  
Minoru Kubo ◽  
Genji Kurisu ◽  
Shinobu Itoh
Keyword(s):  
Catalytic Mechanism ◽  
Substrate Binding ◽  
Active Form ◽  
Copper Ion ◽  
Atomic Resolution ◽  
Oxygen Species ◽  
X Ray ◽  
Oxygen Dynamics ◽  
Insight Into ◽  
Copper Centre

To unveil the activation of dioxygen on the copper centre (Cu<sub>2</sub>O<sub>2</sub>core) of tyrosinase, we performed X-ray crystallograpy with active-form tyrosinase at near atomic resolution. This study provided a novel insight into the catalytic mechanism of the tyrosinase, including the rearrangement of copper-oxygen species as well as the intramolecular migration of copper ion induced by substrate-binding.<br>

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