scholarly journals Sustained Incompatibility between MAPK Signaling and Pathogen Effectors

2020 ◽  
Vol 21 (21) ◽  
pp. 7954
Author(s):  
Julien Lang ◽  
Jean Colcombet
Keyword(s):  
Defense Responses ◽  
Mapk Signaling ◽  
Effector Proteins ◽  
Plant Defense Responses ◽  
Pathogen Effectors ◽  
Current State ◽  
Pathogen Effector ◽  
Mitogen Activated Protein ◽  
Effector Triggered Immunity ◽  
Signaling Components

In plants, Mitogen-Activated Protein Kinases (MAPKs) are important signaling components involved in developemental processes as well as in responses to biotic and abiotic stresses. In this review, we focus on the roles of MAPKs in Effector-Triggered Immunity (ETI), a specific layer of plant defense responses dependent on the recognition of pathogen effector proteins. Having inspected the literature, we synthesize the current state of knowledge concerning this topic. First, we describe how pathogen effectors can manipulate MAPK signaling to promote virulence, and how in parallel plants have developed mechanisms to protect themselves against these interferences. Then, we discuss the striking finding that the recognition of pathogen effectors can provoke a sustained activation of the MAPKs MPK3/6, extensively analyzing its implications in terms of regulation and functions. In line with this, we also address the question of how a durable activation of MAPKs might affect the scope of their substrates, and thereby mediate the emergence of possibly new ETI-specific responses. By highlighting the sometimes conflicting or missing data, our intention is to spur further research in order to both consolidate and expand our understanding of MAPK signaling in immunity.

scholarly journals Harnessing Effector-Triggered Immunity for Durable Disease Resistance

2017 ◽  
Vol 107 (8) ◽  
pp. 912-919 ◽  
Author(s):  
Meixiang Zhang ◽  
Gitta Coaker
Keyword(s):  
Disease Resistance ◽  
Plant Pathogens ◽  
Domain Architecture ◽  
Effector Proteins ◽  
Plant Diseases ◽  
Sources Of Resistance ◽  
Pathogen Effectors ◽  
Pathogen Effector ◽  
Effector Triggered Immunity ◽  
Durable Disease Resistance

Genetic control of plant diseases has traditionally included the deployment of single immune receptors with nucleotide-binding leucine-rich repeat (NLR) domain architecture. These NLRs recognize corresponding pathogen effector proteins inside plant cells, resulting in effector-triggered immunity (ETI). Although ETI triggers robust resistance, deployment of single NLRs can be rapidly overcome by pathogen populations within a single or a few growing seasons. In order to generate more durable disease resistance against devastating plant pathogens, a multitiered strategy that incorporates stacked NLRs combined with other sources of disease resistance is necessary. New genetic and genomic technologies have enabled advancements in identifying conserved pathogen effectors, isolating NLR repertoires from diverse plants, and editing plant genomes to enhance resistance. Significant advancements have also been made in understanding plant immune perception at the receptor level, which has promise for engineering new sources of resistance. Here, we discuss how to utilize recent scientific advancements in a multilayered strategy for developing more durable disease resistance.

scholarly journals Functional Analysis of Plant Defense Suppression and Activation by the Xanthomonas Core Type III Effector XopX

2015 ◽  
Vol 28 (2) ◽  
pp. 180-194 ◽  
Author(s):  
William Stork ◽  
Jung-Gun Kim ◽  
Mary Beth Mudgett
Keyword(s):  
Plant Defense ◽  
Defense Responses ◽  
Effector Proteins ◽  
Immune Signaling ◽  
Type Iii ◽  
Effector Triggered Immunity ◽  
Gene Transcripts ◽  
Type Iii Secretion Effector ◽  
Susceptible Tomato

Many phytopathogenic type III secretion effector proteins (T3Es) have been shown to target and suppress plant immune signaling but perturbation of the plant immune system by T3Es can also elicit a plant response. XopX is a “core” Xanthomonas T3E that contributes to growth and symptom development during Xanthomonas euvesicatoria infection of tomato but its functional role is undefined. We tested the effect of XopX on several aspects of plant immune signaling. XopX promoted ethylene production and plant cell death (PCD) during X. euvesicatoria infection of susceptible tomato and in transient expression assays in Nicotiana benthamiana, which is consistent with its requirement for the development of X. euvesicatoria-induced disease symptoms. Additionally, although XopX suppressed flagellin-induced reactive oxygen species, it promoted the accumulation of pattern-triggered immunity (PTI) gene transcripts. Surprisingly, XopX coexpression with other PCD elicitors resulted in delayed PCD, suggesting antagonism between XopX-dependent PCD and other PCD pathways. However, we found no evidence that XopX contributed to the suppression of effector-triggered immunity during X. euvesicatoria–tomato interactions, suggesting that XopX's primary virulence role is to modulate PTI. These results highlight the dual role of a core Xanthomonas T3E in simultaneously suppressing and activating plant defense responses.

scholarly journals Magnaporthe oryzae Systemic Defense Trigger 1 (MoSDT1)-Mediated Metabolites Regulate Defense Response in Rice

2020 ◽  
Author(s):  
Guihua Duan ◽  
Chunqin Li ◽  
Yanfang Liu ◽  
Xiaoqing Ma ◽  
Qiong Luo ◽  
...  
Keyword(s):  
Plant Defense ◽  
Defense Response ◽  
High Performance ◽  
Receptor Gene ◽  
Active Role ◽  
Defense Responses ◽  
Effector Proteins ◽  
Plant Defense Responses ◽  
Flight Mass Spectrometry ◽  
Metabolic Marker

Abstract Background: Some of the pathogenic effector proteins play an active role in stimulating the plant defense system to strengthen plant resistance.Results: In this study, ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF-MS) was implemented to identify altered metabolites in transgenic rice containing over-expressed M. oryzae Systemic Defense Trigger 1 (MoSDT1) that was infected at three-time points. The characterized dominating metabolites were organic acids and their derivatives, organic oxygen compounds, lipids, and lipid-like molecules. Among the identified metabolites, shikimate, galactinol, trehalose, D-mannose, linolenic acid, dopamine, tyramine, and L-glutamine are precursors for the synthesis of many secondary defense metabolites Carbohydrate, as well as amino acid metabolic, pathways were revealed to be involved in plant defense responses and resistance strengthening.Conclusion: The increasing salicylic acid (SA) and jasmonic acid (JA) content enhanced interactions between JA synthesis/signaling gene, SA synthesis/receptor gene, raffinose/fructose/sucrose synthase gene, and cell wall-related genes all contribute to defense response in rice. The symptoms of rice after M. oryzae infection were significantly alleviated when treated with six identified metabolites, i.e., galactol, tyramine, L-glutamine, L-tryptophan, α-terpinene, and dopamine for 72 h exogenously. Therefore, these metabolites could be utilized as an optimal metabolic marker for M. oryzae defense.#These authors contributed equally to this work.

scholarly journals RIPK1-dependent apoptosis bypasses pathogen blockade of innate signaling to promote immune defense

2017 ◽  
Vol 214 (11) ◽  
pp. 3171-3182 ◽  
Author(s):  
Lance W. Peterson ◽  
Naomi H. Philip ◽  
Alexandra DeLaney ◽  
Meghan A. Wynosky-Dolfi ◽  
Kendra Asklof ◽  
...  
Keyword(s):  
Cell Death ◽  
Kinase Activity ◽  
Cytokine Production ◽  
Mapk Signaling ◽  
Immune Defense ◽  
Effector Proteins ◽  
Host Cells ◽  
Effector Triggered Immunity ◽  
Induced Apoptosis

Many pathogens deliver virulence factors or effectors into host cells in order to evade host defenses and establish infection. Although such effector proteins disrupt critical cellular signaling pathways, they also trigger specific antipathogen responses, a process termed “effector-triggered immunity.” The Gram-negative bacterial pathogen Yersinia inactivates critical proteins of the NF-κB and MAPK signaling cascade, thereby blocking inflammatory cytokine production but also inducing apoptosis. Yersinia-induced apoptosis requires the kinase activity of receptor-interacting protein kinase 1 (RIPK1), a key regulator of cell death, NF-κB, and MAPK signaling. Through the targeted disruption of RIPK1 kinase activity, which selectively disrupts RIPK1-dependent cell death, we now reveal that Yersinia-induced apoptosis is critical for host survival, containment of bacteria in granulomas, and control of bacterial burdens in vivo. We demonstrate that this apoptotic response provides a cell-extrinsic signal that promotes optimal innate immune cytokine production and antibacterial defense, demonstrating a novel role for RIPK1 kinase–induced apoptosis in mediating effector-triggered immunity to circumvent pathogen inhibition of immune signaling.

scholarly journals Molecular Regulation of Host Defense Responses Mediated by Biological Anti-TMV Agent Ningnanmycin

Viruses ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 815 ◽  
Author(s):  
Mengnan An ◽  
Tao Zhou ◽  
Yi Guo ◽  
Xiuxiang Zhao ◽  
Yuanhua Wu
Keyword(s):  
Antiviral Activity ◽  
Calcium Binding ◽  
Defense Responses ◽  
Plant Viruses ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Systemic Resistance ◽  
Mitogen Activated Protein ◽  
Significant Enrichment ◽  
Plant Pathogen Interaction

Ningnanmycin (NNM) belongs to microbial pesticides that display comprehensive antiviral activity against plant viruses. NNM treatment has been shown to efficiently delay or suppress the disease symptoms caused by tobacco mosaic virus (TMV) infection in local-inoculated or systemic-uninoculated tobacco leaves, respectively. However, the underlying molecular mechanism of NNM-mediated antiviral activity remains to be further elucidated. In this study, 414 differentially expressed genes (DEGs), including 383 which were up-regulated and 31 down-regulated, caused by NNM treatment in TMV-infected BY-2 protoplasts, were discovered by RNA-seq. In addition, KEGG analysis indicated significant enrichment of DEGs in the plant–pathogen interaction and MAPK signaling pathway. The up-regulated expression of crucial DEGs, including defense-responsive genes, such as the receptor-like kinase FLS2, RLK1, and the mitogen-activated protein kinase kinase kinase MAPKKK, calcium signaling genes, such as the calcium-binding protein CML19, as well as phytohormone responsive genes, such as the WRKY transcription factors WRKY40 and WRKY70, were confirmed by RT-qPCR. These findings provided valuable insights into the antiviral mechanisms of NNM, which indicated that the agent induces tobacco systemic resistance against TMV via activating multiple plant defense signaling pathways.

scholarly journals The type III effector HopF2Pto targets Arabidopsis RIN4 protein to promote Pseudomonas syringae virulence

2010 ◽  
Vol 107 (5) ◽  
pp. 2349-2354 ◽  
Author(s):  
Mike Wilton ◽  
Rajagopal Subramaniam ◽  
James Elmore ◽  
Corinna Felsensteiner ◽  
Gitta Coaker ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
Effector Proteins ◽  
Type Iii ◽  
Pathogen Effector ◽  
Effector Triggered Immunity ◽  
Type Iii Secretion Effector ◽  
Virulence Target

Plant immunity can be induced by two major classes of pathogen-associated molecules. Pathogen- or microbe-associated molecular patterns (PAMPs or MAMPs) are conserved molecular components of microbes that serve as “non-self” features to induce PAMP-triggered immunity (PTI). Pathogen effector proteins used to promote virulence can also be recognized as “non-self” features or induce a “modified-self” state that can induce effector-triggered immunity (ETI). The Arabidopsis protein RIN4 plays an important role in both branches of plant immunity. Three unrelated type III secretion effector (TTSE) proteins from the phytopathogen Pseudomonas syringae, AvrRpm1, AvrRpt2, and AvrB, target RIN4, resulting in ETI that effectively restricts pathogen growth. However, no pathogenic advantage has been demonstrated for RIN4 manipulation by these TTSEs. Here, we show that the TTSE HopF2Pto also targets Arabidopsis RIN4. Transgenic plants conditionally expressing HopF2Pto were compromised for AvrRpt2-induced RIN4 modification and associated ETI. HopF2Pto interfered with AvrRpt2-induced RIN4 modification in vitro but not with AvrRpt2 activation, suggestive of RIN4 targeting by HopF2Pto. In support of this hypothesis, HopF2Pto interacted with RIN4 in vitro and in vivo. Unlike AvrRpm1, AvrRpt2, and AvrB, HopF2Pto did not induce ETI and instead promoted P. syringae growth in Arabidopsis. This virulence activity was not observed in plants genetically lacking RIN4. These data provide evidence that RIN4 is a major virulence target of HopF2Pto and that a pathogenic advantage can be conveyed by TTSEs that target RIN4.

scholarly journals Mai1 protein acts between host recognition of pathogen effectors and MAPK signaling

2019 ◽  
Author(s):  
Sarah R. Hind ◽  
Robyn Roberts ◽  
Kerry F. Pedley ◽  
Benjamin A. Diner ◽  
Matthew J. Szarzanowicz ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Nicotiana Benthamiana ◽  
Kinase Domain ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Host Recognition ◽  
Mapk Phosphorylation ◽  
Immune Receptors ◽  
Pathogen Effectors ◽  
Mitogen Activated Protein

AbstractThe molecular mechanisms acting between host recognition of pathogen effectors by NOD-like receptor (NLR) proteins and mitogen-activated protein kinase (MAPK) signaling cascades are unknown. MAPKKKα (M3Kα) activates MAPK signaling leading to programmed cell death (PCD) associated with NLR-triggered immunity. We identified a tomato M3Kα-interacting protein, SlMai1, that has 80% amino acid identity with Arabidopsis brassinosteroid kinase 1 (AtBsk1). SlMai1 has a protein kinase domain and a C-terminal tetratricopeptide repeat domain which interacts with the kinase domain of M3Kα. Virus-induced gene silencing of Mai1 homologs in Nicotiana benthamiana increased susceptibility to Pseudomonas syringae and compromised PCD induced by four NLR proteins. PCD was restored by expression of a synthetic SlMai1 gene that resists silencing. Expression of AtBsk1 did not restore PCD in Mai1-silenced plants, suggesting SlMai1 is functionally divergent from AtBsk1. PCD caused by overexpression of M3Kα or MKK2 was unaffected by Mai1 silencing indicating Mai1 acts upstream of these proteins. Co-expression of Mai1 with M3Kα in leaves enhanced MAPK phosphorylation and accelerated PCD. These findings reveal Mai1 as a molecular link acting between host recognition of pathogens and MAPK signaling.Author SummaryPlants use intracellular immune receptors to detect and respond to specific effector proteins which pathogens translocate into the host cell as part of their infection process. Localized programmed cell death (PCD) involving a mitogen-activated protein kinase (MAPK) cascade is an important host response associated with effector-triggered immunity, although the molecular connections between immune receptors and MAPK signaling is unknown. The Mai1 protein was found to act downstream of multiple immune receptors in Nicotiana benthamiana and to physically interact with MAPKKKα. The Mai1-MAPKKKα interaction enhances MAPK phosphorylation, triggers PCD and promotes disease resistance.

scholarly journals The PTI to ETI Continuum in Phytophthora-Plant Interactions

2020 ◽  
Vol 11 ◽  
Author(s):  
Zunaira Afzal Naveed ◽  
Xiangying Wei ◽  
Jianjun Chen ◽  
Hira Mubeen ◽  
Gul Shad Ali
Keyword(s):  
Host Defense ◽  
Induced Defense ◽  
Plant Immunity ◽  
Defense Responses ◽  
Mapk Signaling ◽  
Cell Trafficking ◽  
Plant Interactions ◽  
Physiological Processes ◽  
Effector Triggered Immunity ◽  
Induced Defense Responses

Phytophthora species are notorious pathogens of several economically important crop plants. Several general elicitors, commonly referred to as Pathogen-Associated Molecular Patterns (PAMPs), from Phytophthora spp. have been identified that are recognized by the plant receptors to trigger induced defense responses in a process termed PAMP-triggered Immunity (PTI). Adapted Phytophthora pathogens have evolved multiple strategies to evade PTI. They can either modify or suppress their elicitors to avoid recognition by host and modulate host defense responses by deploying hundreds of effectors, which suppress host defense and physiological processes by modulating components involved in calcium and MAPK signaling, alternative splicing, RNA interference, vesicle trafficking, cell-to-cell trafficking, proteolysis and phytohormone signaling pathways. In incompatible interactions, resistant host plants perceive effector-induced modulations through resistance proteins and activate downstream components of defense responses in a quicker and more robust manner called effector-triggered-immunity (ETI). When pathogens overcome PTI—usually through effectors in the absence of R proteins—effectors-triggered susceptibility (ETS) ensues. Qualitatively, many of the downstream defense responses overlap between PTI and ETI. In general, these multiple phases of Phytophthora-plant interactions follow the PTI-ETS-ETI paradigm, initially proposed in the zigzag model of plant immunity. However, based on several examples, in Phytophthora-plant interactions, boundaries between these phases are not distinct but are rather blended pointing to a PTI-ETI continuum.

scholarly journals Danger-associated peptide signaling in Arabidopsis requires clathrin

2016 ◽  
Vol 113 (39) ◽  
pp. 11028-11033 ◽  
Author(s):  
Fausto Andres Ortiz-Morea ◽  
Daniel V. Savatin ◽  
Wim Dejonghe ◽  
Rahul Kumar ◽  
Yu Luo ◽  
...  
Keyword(s):  
Brefeldin A ◽  
Defense Responses ◽  
Cellular Damage ◽  
Dependent Manner ◽  
Plant Defense Responses ◽  
Direct Binding ◽  
Endogenous Elicitor ◽  
Golgi Network ◽  
Signaling Components ◽  
Adp Ribosylation Factor

The Arabidopsis thaliana endogenous elicitor peptides (AtPeps) are released into the apoplast after cellular damage caused by pathogens or wounding to induce innate immunity by direct binding to the membrane-localized leucine-rich repeat receptor kinases, PEP RECEPTOR1 (PEPR1) and PEPR2. Although the PEPR-mediated signaling components and responses have been studied extensively, the contributions of the subcellular localization and dynamics of the active PEPRs remain largely unknown. We used live-cell imaging of the fluorescently labeled and bioactive pep1 to visualize the intracellular behavior of the PEPRs in the Arabidopsis root meristem. We found that AtPep1 decorated the plasma membrane (PM) in a receptor-dependent manner and cointernalized with PEPRs. Trafficking of the AtPep1-PEPR1 complexes to the vacuole required neither the trans-Golgi network/early endosome (TGN/EE)-localized vacuolar H+-ATPase activity nor the function of the brefeldin A-sensitive ADP-ribosylation factor-guanine exchange factors (ARF-GEFs). In addition, AtPep1 and different TGN/EE markers colocalized only rarely, implying that the intracellular route of this receptor–ligand pair is largely independent of the TGN/EE. Inducible overexpression of the Arabidopsis clathrin coat disassembly factor, Auxilin2, which inhibits clathrin-mediated endocytosis (CME), impaired the AtPep1-PEPR1 internalization and compromised AtPep1-mediated responses. Our results show that clathrin function at the PM is required to induce plant defense responses, likely through CME of cell surface-located signaling components.

scholarly journals Effectors from Wheat Rust Fungi Suppress Multiple Plant Defense Responses

2017 ◽  
Vol 107 (1) ◽  
pp. 75-83 ◽  
Author(s):  
Sowmya R. Ramachandran ◽  
Chuntao Yin ◽  
Joanna Kud ◽  
Kiwamu Tanaka ◽  
Aaron K. Mahoney ◽  
...  
Keyword(s):  
Plant Defense ◽  
Pseudomonas Syringae ◽  
Hypersensitive Response ◽  
Defense Responses ◽  
Effector Proteins ◽  
R Gene ◽  
Plant Defense Responses ◽  
Functional Studies ◽  
Rust Diseases ◽  
Suppression Assay

Fungi that cause cereal rust diseases (genus Puccinia) are important pathogens of wheat globally. Upon infection, the fungus secretes a number of effector proteins. Although a large repository of putative effectors has been predicted using bioinformatic pipelines, the lack of available high-throughput effector screening systems has limited functional studies on these proteins. In this study, we mined the available transcriptomes of Puccinia graminis and P. striiformis to look for potential effectors that suppress host hypersensitive response (HR). Twenty small (<300 amino acids), secreted proteins, with no predicted functions were selected for the HR suppression assay using Nicotiana benthamiana, in which each of the proteins were transiently expressed and evaluated for their ability to suppress HR caused by four cytotoxic effector‐R gene combinations (Cp/Rx, ATR13/RPP13, Rpt2/RPS‐2, and GPA/RBP‐1) and one mutated R gene—Pto(Y207D). Nine out of twenty proteins, designated Shr1 to Shr9 (suppressors of hypersensitive response), were found to suppress HR in N. benthamiana. These effectors varied in the effector-R gene defenses they suppressed, indicating these pathogens can interfere with a variety of host defense pathways. In addition to HR suppression, effector Shr7 also suppressed PAMP-triggered immune response triggered by flg22. Finally, delivery of Shr7 through Pseudomonas fluorescens EtHAn suppressed nonspecific HR induced by Pseudomonas syringae DC3000 in wheat, confirming its activity in a homologous system. Overall, this study provides the first evidence for the presence of effectors in Puccinia species suppressing multiple plant defense responses.

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