microbial pathoge...
Follow
Find
2.1K views | +3 today
 
Rescooped by Jim Alfano from Plants&Bacteria
onto microbial pathogenesis and plant immunity
Scoop.it!

A Bacterial Tyrosine Phosphatase Inhibits Plant Pattern Recognition Receptor Activation

A Bacterial Tyrosine Phosphatase Inhibits Plant Pattern Recognition Receptor Activation | microbial pathogenesis and plant immunity | Scoop.it

Scooped from: Science, 2014

Authors: Alberto P. Macho, Benjamin Schwessinger, Vardis Ntoukakis, Alexandre Brutus, Cécile Segonzac, Sonali Roy, Yasuhiro Kadota, Man-Ho Oh, Jan Sklenar, Paul Derbyshire, Rosa Lozano-Durán, Frederikke Gro Malinovsky, Jacqueline Monaghan, Frank L. Menke, Steven C. Huber, Sheng Yang He and Cyril Zipfel.

 

Summary: 

Innate immunity relies on the perception of pathogen-associated molecular patterns (PAMPs) by pattern-recognition receptors (PRRs) located on the host cell’s surface. Many plant PRRs are kinases. Here, we report that the Arabidopsis receptor kinase EF-TU RECEPTOR EFR, which perceives the elf18 peptide derived from bacterial elongation factor Tu, is activated upon ligand binding by phosphorylation on its tyrosine residues. Phosphorylation of a single tyrosine residue, Y836, is required for activation of EFR and downstream immunity to the phytopathogenic bacterium Pseudomonas syringae. A tyrosine phosphatase, HopAO1, secreted by P. syringae, reduces EFR phosphorylation and derails subsequent immune responses. Thus host and pathogen battle to take control of PRR tyrosine phosphorylation used to initiate anti-bacterial immunity.


Via Freddy Monteiro
Jim Alfano's insight:

Very interesting finding - A long sought target of the HopAO1 effector. HopAO1 also suppresses ETI - so additional targets remain undiscovered.

more...
No comment yet.

From around the web

microbial pathogenesis and plant immunity
Your new post is loading...
Your new post is loading...
Rescooped by Jim Alfano from Plant-microbe interactions (on the plant's side)
Scoop.it!

What lies beneath: belowground defense strategies in plants

What lies beneath: belowground defense strategies in plants | microbial pathogenesis and plant immunity | Scoop.it

Diseases caused by soil-borne pathogens result worldwide in significant yield losses in economically important crops. In contrast to foliar diseases, relatively little is known about the nature of root defenses against these pathogens. This review summarizes the current knowledge on root infection strategies, root-specific preformed barriers, pathogen recognition, and defense signaling. Studies reviewed here suggest that many commonalities as well as differences exist in defense strategies employed by roots and foliar tissues during pathogen attack. Importantly, in addition to pathogens, plant roots interact with a plethora of non-pathogenic and symbiotic microorganisms. Therefore, a good understanding of how plant roots interact with the microbiome would be particularly important to engineer resistance to root pathogens without negatively altering root-beneficial microbe interactions.

 

 


Via Christophe Jacquet
more...
No comment yet.
Rescooped by Jim Alfano from Plants and Microbes
Scoop.it!

eLife: The kinase LYK5 is a major chitin receptor in Arabidopsis and forms a chitin-induced complex with related kinase CERK1 (2014)

eLife: The kinase LYK5 is a major chitin receptor in Arabidopsis and forms a chitin-induced complex with related kinase CERK1 (2014) | microbial pathogenesis and plant immunity | Scoop.it

Chitin is a fungal microbe-associated molecular pattern (MAMP) that is recognized in Arabidopsis by a lysin motif receptor kinase (LYK), AtCERK1. Previous research suggested that AtCERK1 is the major chitin receptor in plants and mediates chitin-induced signaling through homodimerization and phosphorylation. However, the reported chitin binding affinity of AtCERK1 is quite low, suggesting another receptor with high chitin binding affinity might be present. Here, we propose that AtLYK5 is the primary chitin receptor in Arabidopsis. Mutations in AtLYK5 resulted in a significant reduction in the plant chitin response. However, AtLYK5 shares overlapping function with AtLYK4 and, therefore, only AtLYK4/AtLYK5-2 double mutants show a complete loss of chitin response. AtLYK5 interacts with AtCERK1 in a chitin-dependent manner. Chitin binding to AtLYK5 is indispensable for chitin-induced AtCERK1 phosphorylation. AtLYK5 binds chitin at a higher affinity than AtCERK1. The data suggest that AtLYK5 is the primary receptor for chitin to induce plant immunity.


Via Kamoun Lab @ TSL
more...
Jean-Michel Ané's curator insight, October 24, 12:06 PM

A must read if you are interested in Nod and Myc factor receptors too...

Scooped by Jim Alfano
Scoop.it!

Proline Isomerization of the Immune Receptor-Interacting Protein RIN4 by a Cyclophilin Inhibits Effector-Triggered Immunity in Arabidopsis: Cell Host & Microbe

Proline Isomerization of the Immune Receptor-Interacting Protein RIN4 by a Cyclophilin Inhibits Effector-Triggered Immunity in Arabidopsis: Cell Host & Microbe | microbial pathogenesis and plant immunity | Scoop.it

In the absence of pathogen infection, plant effector-triggered immune (ETI) receptors are maintained in a preactivation state by intermolecular interactions with other host proteins. Pathogen effector-induced alterations activate the receptor. In Arabidopsis, the ETI receptor RPM1 is activated via bacterial effector AvrB-induced phosphorylation of the RPM1-interacting protein RIN4 at Threonine 166. We find that RIN4 also interacts with the prolyl-peptidyl isomerase (PPIase) ROC1, which is reduced upon RIN4 Thr166 phosphorylation. ROC1 suppresses RPM1 immunity in a PPIase-dependent manner. Consistent with this, RIN4 Pro149 undergoes cis/trans isomerization in the presence of ROC1. While the RIN4P149V mutation abolishes RPM1 resistance, the deletion of Pro149 leads to RPM1 activation in the absence of RIN4 phosphorylation. These results support a model in which RPM1 directly senses conformational changes in RIN4 surrounding Pro149 that is controlled by ROC1. RIN4 Thr166 phosphorylation indirectly regulates RPM1 resistance by modulating the ROC1-mediated RIN4 isomerization.

more...
No comment yet.
Rescooped by Jim Alfano from Plant-microbe interactions (on the plant's side)
Scoop.it!

Pepper pathogenesis-related protein 4c is a plasma-membrane localized cysteine protease inhibitor that is required for plant cell death and defense signaling

Pepper pathogenesis-related protein 4c is a plasma-membrane localized cysteine protease inhibitor that is required for plant cell death and defense signaling | microbial pathogenesis and plant immunity | Scoop.it

Xanthomonas campestris pv. vesicatoria (Xcv) type III effector AvrBsT triggers programmed cell death (PCD) and activates the hypersensitive response (HR) in plants. Here, we isolated and identified the plasma-membrane localized pathogenesis-related (PR) protein 4c gene (CaPR4c) from pepper (Capsicum annuum) leaves undergoing AvrBsT-triggered HR cell death. CaPR4c encodes a protein with a signal peptide and a Barwin domain. Recombinant CaPR4c protein expressed in Escherichia coli exhibited cysteine protease-inhibitor activity and ribonuclease (RNase) activity. Subcellular localization analyses revealed that CaPR4c localized to the plasma membrane in plant cells. CaPR4c expression was rapidly and specifically induced by avirulent Xcv (avrBsT) infection. Transient expression of CaPR4c caused HR cell death in pepper leaves, which was accompanied by enhanced accumulation of H2O2 and significant induction of some defense response genes. Deletion of the signal peptide from CaPR4c abolished the induction of HR cell death, indicating a requirement for plasma-membrane localization of CaPR4c for HR cell death. CaPR4c silencing in pepper disrupted both basal and AvrBsT-triggered resistance responses, and enabled Xcv proliferation in infected leaves. H2O2 accumulation, cell-death induction, and defense-response gene expression were distinctly reduced in CaPR4c-silenced pepper. CaPR4c overexpression in transgenic Arabidopsis plants conferred greater resistance against infection by Pseudomonas syringae pv. tomato and Hyaloperonospora arabidopsidis. These results collectively suggest that CaPR4c plays an important role in plant cell death and defense signaling.

 

 


Via Christophe Jacquet
more...
No comment yet.
Rescooped by Jim Alfano from Plant Immunity And Microbial Effectors
Scoop.it!

Bacteria-triggered systemic immunity in barley appears to be associated with WRKY and ETHYLENE RESPONSIVE FACTORs but not with salicylic acid

Leaf-to-leaf, systemic immune signaling known as systemic acquired resistance (SAR) is poorly understood in monocotyledonous plants.

Via IPM Lab
more...
No comment yet.
Rescooped by Jim Alfano from Plant-microbe interactions (on the plant's side)
Scoop.it!

NOD-like receptor cooperativity in effector-triggered immunity

NOD-like receptor cooperativity in effector-triggered immunity | microbial pathogenesis and plant immunity | Scoop.it
Highlights



Plant nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) recognize intracellular pathogen effector proteins.


Self-association of plant NLRs is required for immune signaling.


Heteromeric NLR assemblies link sensor and executor NLR.

Intracellular nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) are basic elements of innate immunity in plants and animals. Whereas animal NLRs react to conserved microbe- or damage-associated molecular patterns, plant NLRs intercept the actions of diverse pathogen virulence factors (effectors). In this review, we discuss recent genetic and molecular evidence for functional NLR pairs, and discuss the significance of NLR self-association and heteromeric NLR assemblies in the triggering of downstream signaling pathways. We highlight the versatility and impact of cooperating NLR pairs that combine pathogen sensing with the initiation of defense signaling in both plant and animal immunity. We propose that different NLR receptor molecular configurations provide opportunities for fine-tuning resistance pathways and enhancing the host's pathogen recognition spectrum to keep pace with rapidly evolving microbial populations.

Via Christophe Jacquet
more...
No comment yet.
Rescooped by Jim Alfano from Plant-microbe interaction
Scoop.it!

Salicylic Acid Regulates Arabidopsis Microbial Pattern Receptor Kinase Levels and Signaling

Salicylic Acid Regulates Arabidopsis Microbial Pattern Receptor Kinase Levels and Signaling | microbial pathogenesis and plant immunity | Scoop.it

In Arabidopsis thaliana, responses to pathogen-associated molecular patterns (PAMPs) are mediated by cell surface pattern recognition receptors (PRRs) and include the accumulation of reactive oxygen species, callose deposition in the cell wall, and the generation of the signal molecule salicylic acid (SA). SA acts in a positive feedback loop with ACCELERATED CELL DEATH6 (ACD6), a membrane protein that contributes to immunity. This work shows that PRRs associate with and are part of the ACD6/SA feedback loop. ACD6 positively regulates the abundance of several PRRs and affects the responsiveness of plants to two PAMPs. SA accumulation also causes increased levels of PRRs and potentiates the responsiveness of plants to PAMPs. Finally, SA induces PRR- and ACD6-dependent signaling to induce callose deposition independent of the presence of PAMPs. This PAMP-independent effect of SA causes a transient reduction of PRRs and ACD6-dependent reduced responsiveness to PAMPs. Thus, SA has a dynamic effect on the regulation and function of PRRs. Within a few hours, SA signaling promotes defenses and downregulates PRRs, whereas later (within 24 to 48 h) SA signaling upregulates PRRs, and plants are rendered more responsive to PAMPs. These results implicate multiple modes of signaling for PRRs in response to PAMPs and SA.


Via Suayib Üstün
more...
No comment yet.
Rescooped by Jim Alfano from Molecular Biology and Life Science
Scoop.it!

Nature Communications: Long-distance endosome trafficking drives fungal effector production during plant infection (2014)

Nature Communications: Long-distance endosome trafficking drives fungal effector production during plant infection (2014) | microbial pathogenesis and plant immunity | Scoop.it

To cause plant disease, pathogenic fungi can secrete effector proteins into plant cells to suppress plant immunity and facilitate fungal infection. Most fungal pathogens infect plants using very long strand-like cells, called hyphae, that secrete effectors from their tips into host tissue. How fungi undergo long-distance cell signalling to regulate effector production during infection is not known. Here we show that long-distance retrograde motility of early endosomes (EEs) is necessary to trigger transcription of effector-encoding genes during plant infection by the pathogenic fungus Ustilago maydis. We demonstrate that motor-dependent retrograde EE motility is necessary for regulation of effector production and secretion during host cell invasion. We further show that retrograde signalling involves the mitogen-activated kinase Crk1 that travels on EEs and participates in control of effector production. Fungal pathogens therefore undergo long-range signalling to orchestrate host invasion.


Via Kamoun Lab @ TSL, Shaikhul Islam
more...
No comment yet.
Rescooped by Jim Alfano from The Plant Microbiome
Scoop.it!

Nature communications: Niche and host-associated functional signatures of the root surface microbiome

Nature communications: Niche and host-associated functional signatures of the root surface microbiome | microbial pathogenesis and plant immunity | Scoop.it

Plant microbiomes are critical to host adaptation and impact plant productivity and health. Root-associated microbiomes vary by soil and host genotype, but the contribution of these factors to community structure and metabolic potential has not been fully addressed. Here we characterize root microbial communities of two disparate agricultural crops grown in the same natural soil in a controlled and replicated experimental system. Metagenomic (genetic potential) analysis identifies a core set of functional genes associated with root colonization in both plant hosts, and metatranscriptomic (functional expression) analysis revealed that most genes enriched in the root zones are expressed. Root colonization requires multiple functional capabilities, and these capabilities are enriched at the community level. Differences between the root-associated microbial communities from different plants are observed at the genus or species level, and are related to root-zone environmental factors.


Via Stéphane Hacquard
more...
No comment yet.
Scooped by Jim Alfano
Scoop.it!

‘Animated Life: Seeing the Invisible’

‘Animated Life: Seeing the Invisible’ | microbial pathogenesis and plant immunity | Scoop.it
This animated documentary celebrates the scientist Antonie van Leeuwenhoek, whose discovery of microbes would change our view of the biological world.
Jim Alfano's insight:

This is a great video for scientists, students getting into microbiology, or even non-scientists.

more...
No comment yet.
Rescooped by Jim Alfano from Effectors and Plant Immunity
Scoop.it!

Cell Host Microbes: Convergent Targeting of a Common Host Protein-Network by Pathogen Effectors from Three Kingdoms of Life (2014)

Cell Host Microbes: Convergent Targeting of a Common Host Protein-Network by Pathogen Effectors from Three Kingdoms of Life (2014) | microbial pathogenesis and plant immunity | Scoop.it

While conceptual principles governing plant immunity are becoming clear, its systems-level organization and the evolutionary dynamic of the host-pathogen interface are still obscure. We generated a systematic protein-protein interaction network of virulence effectors from the ascomycete pathogen Golovinomyces orontii and Arabidopsis thaliana host proteins. We combined this data set with corresponding data for the eubacterial pathogen Pseudomonas syringae and the oomycete pathogen Hyaloperonospora arabidopsidis. The resulting network identifies host proteins onto which intraspecies and interspecies pathogen effectors converge. Phenotyping of 124 Arabidopsis effector-interactor mutants revealed a correlation between intraspecies and interspecies convergence and several altered immune response phenotypes. Several effectors and the most heavily targeted host protein colocalized in subnuclear foci. Products of adaptively selected Arabidopsis genes are enriched for interactions with effector targets. Our data suggest the existence of a molecular host-pathogen interface that is conserved across Arabidopsis accessions, while evolutionary adaptation occurs in the immediate network neighborhood of effector targets.

 

Ralf Weßling, Petra Epple, Stefan Altmann,Yijian He, Li Yang, Stefan R. Henz, Nathan McDonald, Kristin Wiley, Kai Christian Bader, Christine Glaßer, M. Shahid Mukhtar, Sabine Haigis, Lila Ghamsari, Amber E. Stephens, Joseph R. Ecker, Marc Vidal, Jonathan D.G. Jones,Klaus F.X. Mayer, Emiel Ver Loren van Themaat, Detlef Weigel, Paul Schulze-Lefert, Jeffery L. Dangl, Ralph Panstruga, and Pascal Braun


Via Nicolas Denancé
more...
CP's curator insight, September 12, 4:04 AM

add your insight...

Suayib Üstün's comment, September 12, 4:45 AM
HopBF1 is HopZ4!
Suayib Üstün's curator insight, September 12, 5:14 AM

HopBF1 is HopZ4...

Scooped by Jim Alfano
Scoop.it!

Biochem. J. (2014) Immediate Publication - 2. Zouhir et al.

Biochem. J. (2014) Immediate Publication - 2. Zouhir et al. | microbial pathogenesis and plant immunity | Scoop.it

Salmonella infections are a leading cause of bacterial foodborne illness in the United States and the European Union. Antimicrobial therapy is often administered to treat the infection but increasing isolates are being detected that demonstrate resistance to multiple antibiotics. Salmonella enterica contains two virulence related type III secretion systems (T3SS): one promotes invasion of the intestine and the other one mediates systemic disease. Both of them secrete the SlrP protein acting as E3 ubiquitin ligase in human host cells where it targets thioredoxin-1 (Trx1). SlrP belongs to the NEL family of bacterial E3 ubiquitin ligases that have been observed in two distinct autoinhibitory conformations. We solved the 3D structure of the SlrP-Trx1 complex and determined the Trx1 ubiquitination site. The description of the substrate-binding mode sheds light on the first step of the activation mechanism of SlrP. Comparison with the available structural data of other NEL effectors allowed us to gain new insights into their autoinhibitory mechanism. We propose a molecular mechanism for the regulation of SlrP in which structural constraints sequestrating the NEL domain would be sequentially released. This work thus constitutes a new milestone in the understanding of how these T3SS effectors influence pathogen virulence. It also provides the fundamental basis for the future development of new antimicrobials.

more...
No comment yet.
Scooped by Jim Alfano
Scoop.it!

The Secreted Peptide PIP1 Amplifies Immunity through Receptor-Like Kinase 7

The Secreted Peptide PIP1 Amplifies Immunity through Receptor-Like Kinase 7 | microbial pathogenesis and plant immunity | Scoop.it

In plants, innate immune responses are initiated by plasma membrane-located pattern recognition receptors (PRRs) upon recognition of elicitors, including exogenous pathogen-associated molecular patterns (PAMPs) and endogenous damage-associated molecular patterns (DAMPs). Arabidopsis thaliana produces more than 1000 secreted peptide candidates, but it has yet to be established whether any of these act as elicitors. Here we identified an A. thaliana gene family encoding precursors of PAMP-induced secreted peptides (prePIPs) through an in-silico approach. The expression of some members of the family, including prePIP1 and prePIP2, is induced by a variety of pathogens and elicitors. Subcellular localization and proteolytic processing analyses demonstrated that the prePIP1 product is secreted into extracellular spaces where it is cleaved at the C-terminus. Overexpression of prePIP1 and prePIP2, or exogenous application of PIP1 and PIP2 synthetic peptides corresponding to the C-terminal conserved regions in prePIP1 and prePIP2, enhanced immune responses and pathogen resistance in A. thaliana. Genetic and biochemical analyses suggested that the receptor-like kinase 7 (RLK7) functions as a receptor of PIP1. Once perceived by RLK7, PIP1 initiates overlapping and distinct immune signaling responses together with the DAMP PEP1. PIP1 and PEP1 cooperate in amplifying the immune responses triggered by the PAMP flagellin. Collectively, these studies provide significant insights into immune modulation by Arabidopsis endogenous secreted peptides.

 

more...
No comment yet.
Rescooped by Jim Alfano from Plant-microbe interaction
Scoop.it!

Frontiers | The Salmonella effector protein SpvC, a phosphothreonine lyase is functional in plant cells | Plant-Microbe Interaction

Frontiers | The Salmonella effector protein SpvC, a phosphothreonine lyase is functional in plant cells | Plant-Microbe Interaction | microbial pathogenesis and plant immunity | Scoop.it
Salmonella is one of the most prominent causes of food poisoning and growing evidence indicates that contaminated fruits and vegetables are an increasing concern for human health. Successful infection demands the suppression of the host immune system, which is often achieved via injection of bacterial effector proteins into host cells. In this report we present the function of Salmonella effector protein in plant cell, supporting the new concept of trans-kingdom competence of this bacterium. We screened a range of Salmonella Typhimurium effector proteins for interference with plant immunity. Among these, the phosphothreonine lyase SpvC attenuated the induction of immunity-related genes when present in plant cells. Using in vitro and in vivo systems we show that this effector protein interacts with and dephosphorylates activated Arabidopsis Mitogen-activated Protein Kinase 6 (MPK6), thereby inhibiting defense signaling. Moreover, the requirement of Salmonella SpvC was shown by the decreased proliferation of the ΔspvC mutant in Arabidopsis plants. These results suggest that some Salmonella effector proteins could have a conserved function during proliferation in different hosts. The fact that Salmonella and other Enterobacteriaceae use plants as hosts strongly suggests that plants represent a much larger reservoir for animal pathogens than so far estimated.

Via Suayib Üstün
more...
No comment yet.
Rescooped by Jim Alfano from Plants and Microbes
Scoop.it!

PLOS Genetics: The Nuclear Immune Receptor RPS4 Is Required for RRS1SLH1-Dependent Constitutive Defense Activation in Arabidopsis thaliana (2014)

PLOS Genetics: The Nuclear Immune Receptor RPS4 Is Required for RRS1SLH1-Dependent Constitutive Defense Activation in Arabidopsis thaliana (2014) | microbial pathogenesis and plant immunity | Scoop.it

Plant nucleotide-binding leucine-rich repeat (NB-LRR) disease resistance (R) proteins recognize specific “avirulent” pathogen effectors and activate immune responses. NB-LRR proteins structurally and functionally resemble mammalian Nod-like receptors (NLRs). How NB-LRR and NLR proteins activate defense is poorly understood. The divergently transcribed Arabidopsis R genes, RPS4 (resistance to Pseudomonas syringae 4) and RRS1 (resistance to Ralstonia solanacearum 1), function together to confer recognition of PseudomonasAvrRps4 and Ralstonia PopP2. RRS1 is the only known recessive NB-LRR R gene and encodes a WRKY DNA binding domain, prompting suggestions that it acts downstream of RPS4 for transcriptional activation of defense genes. We define here the early RRS1-dependent transcriptional changes upon delivery of PopP2 via Pseudomonas type III secretion. The Arabidopsis slh1 (sensitive to low humidity 1) mutant encodes an RRS1 allele (RRS1SLH1) with a single amino acid (leucine) insertion in the WRKY DNA-binding domain. Its poor growth due to constitutive defense activation is rescued at higher temperature. Transcription profiling data indicate that RRS1SLH1-mediated defense activation overlaps substantially with AvrRps4- and PopP2-regulated responses. To better understand the genetic basis of RPS4/RRS1-dependent immunity, we performed a genetic screen to identify suppressor of slh1 immunity (sushi) mutants. We show that many sushi mutants carry mutations in RPS4, suggesting that RPS4 acts downstream or in a complex with RRS1. Interestingly, several mutations were identified in a domain C-terminal to the RPS4 LRR domain. Using an Agrobacterium-mediated transient assay system, we demonstrate that the P-loop motif of RPS4 but not of RRS1SLH1 is required for RRS1SLH1 function. We also recapitulate the dominant suppression of RRS1SLH1 defense activation by wild type RRS1 and show this suppression requires an intact RRS1 P-loop. These analyses of RRS1SLH1shed new light on mechanisms by which NB-LRR protein pairs activate defense signaling, or are held inactive in the absence of a pathogen effector.


Via Kamoun Lab @ TSL
more...
No comment yet.
Rescooped by Jim Alfano from Plant-microbe interactions (on the plant's side)
Scoop.it!

Ca2+ signalling in plant immune response: from pattern recognition receptors to Ca2+ decoding mechanisms.

Ca2+ signalling in plant immune response: from pattern recognition receptors to Ca2+ decoding mechanisms. | microbial pathogenesis and plant immunity | Scoop.it

Ca2+ is a ubiquitous second messenger for cellular signalling in various stresses and developmental processes. Here, we summarize current developments in the roles of Ca2+ during plant immunity responses. We discuss the early perception events preceding and necessary for triggering cellular Ca2+ fluxes, the potential Ca2+-permeable channels, the decoding of Ca2+ signals predominantly via Ca2+-dependent phosphorylation events and transcriptional reprogramming. To highlight the complexity of the cellular signal network, we briefly touch on the interplay between Ca2+-dependent signalling and selected major signalling mechanisms – with special emphasis on reactive oxygen species at local and systemic levels.


Via Christophe Jacquet
more...
No comment yet.
Rescooped by Jim Alfano from Plant-microbe interactions (on the plant's side)
Scoop.it!

A receptor-like protein mediates the response to pectin modification by activating brassinosteroid signaling

A receptor-like protein mediates the response to pectin modification by activating brassinosteroid signaling | microbial pathogenesis and plant immunity | Scoop.it
Significance

Plant growth and development depend on the biosynthesis and remodeling of the cell wall. To coordinate these two processes, surveillance mechanisms have evolved to monitor the state of the cell wall. The brassinosteroid (BR) hormone signaling pathway plays an essential role in growth control and regulates the expression of a plethora of cell wall-related genes. We have previously shown that feedback signaling from the wall can modulate the outputs of the BR pathway, ensuring cell wall homeostasis and integrity. Here, we identified a receptor-like protein (RLP44), which mediates the activation of BR signaling through direct interaction with the BR coreceptor BAK1. Thus, RLP44 integrates cell wall surveillance with hormone signaling to control cell wall integrity and growth.
Abstract

The brassinosteroid (BR) signaling module is a central regulator of plant morphogenesis, as indicated by the large number of BR-responsive cell wall-related genes and the severe growth defects of BR mutants. Despite a detailed knowledge of the signaling components, the logic of this auto-/paracrine signaling module in growth control remains poorly understood. Recently, extensive cross-talk with other signaling pathways has been shown, suggesting that the outputs of BR signaling, such as gene-expression changes, are subject to complex control mechanisms. We previously provided evidence for a role of BR signaling in a feedback loop controlling the integrity of the cell wall. Here, we identify the first dedicated component of this feedback loop: a receptor-like protein (RLP44), which is essential for the compensatory triggering of BR signaling upon inhibition of pectin de-methylesterification in the cell wall. RLP44 is required for normal growth and stress responses and connects with the BR signaling pathway, presumably through a direct interaction with the regulatory receptor-like kinase BAK1. These findings corroborate a role for BR in controlling the sensitivity of a feedback signaling module involved in maintaining the physico-chemical homeostasis of the cell wall during cell expansion.

Via Christophe Jacquet
more...
No comment yet.
Rescooped by Jim Alfano from Plant-microbe interactions (on the plant's side)
Scoop.it!

Twists and Turns: My Career Path and Concerns About the Future

Twists and Turns: My Career Path and Concerns About the Future | microbial pathogenesis and plant immunity | Scoop.it
THE Genetics Society of America’s Thomas Hunt Morgan Medal is awarded to an individual GSA member for lifetime achievement in the field of genetics. The 2014 recipient is Frederick Ausubel, whose 40-year career has centered on host–microbe interactions and host innate immunity. He is widely recognized as a key scientist responsible for establishing the modern postrecombinant DNA field of host–microbe interactions using simple nonvertebrate hosts. He has used genetic approaches to conduct pioneering work that spawned six related areas of research: the evolution and regulation of Rhizobium genes involved in symbiotic nitrogen fixation; the regulation of Rhizobium genes by two-component regulatory systems involving histidine kinases; the establishment of Arabidopsis thaliana as a worldwide model system; the identification of a large family of plant disease resistance genes; the identification of so-called multi-host bacterial pathogens; and the demonstration that Caenorhabditis elegans has an evolutionarily conserved innate immune system that shares features of both plant and mammalian immunity.

Via Christophe Jacquet
more...
No comment yet.
Rescooped by Jim Alfano from Plant pathogens and pests
Scoop.it!

Agroinfiltration by Cytokinin-Producing Agrobacterium sp. Strain GV3101 Primes Defense Responses in Nicotiana tabacum

Agroinfiltration by Cytokinin-Producing Agrobacterium sp. Strain GV3101 Primes Defense Responses in Nicotiana tabacum | microbial pathogenesis and plant immunity | Scoop.it

Transient infiltrations in tobacco are commonly used in plant studies, but the host response to different disarmed Agrobacterium strains is not fully understood. The present study shows that pretreatment with disarmed Agrobacterium tumefaciens GV3101 primes the defense response to subsequent infection by Pseudomonas syringae in Nicotiana tabacum. The presence of a trans-zeatin synthase (tzs) gene in strain GV3101 may be partly responsible for the priming response, as the tzs-deficient Agrobacterium sp. strain LBA4404 only weakly imparts such responses. Besides inducing the expression of defense-related genes like PR-1 and NHL10, GV3101 pretreatment increased the expression of tobacco mitogen-activated protein kinase (MAPK) pathway genes like MEK2, WIPK (wound-induced protein kinase), and SIPK (salicylic acid-induced protein kinase). Furthermore, the GV3101 strain showed a stronger effect than the LBA4404 strain in activating phosphorylation of the tobacco MAPK, WIPK and SIPK, which presumably prime the plant immune machinery. Lower doses of exogenously applied cytokinins increased the activation of MAPK, while higher doses decreased the activation, suggesting a balanced level of cytokinins is required to generate defense response in planta. The current study serves as a cautionary warning for plant researchers over the choice of Agrobacterium strains and their possible consequences on subsequent pathogen-related studies.

 

 


Via Christophe Jacquet
more...
No comment yet.
Rescooped by Jim Alfano from Plants and Microbes
Scoop.it!

New Phytologist: TAL effectors – pathogen strategies and plant resistance engineering (2014)

New Phytologist: TAL effectors – pathogen strategies and plant resistance engineering (2014) | microbial pathogenesis and plant immunity | Scoop.it

Transcription activator-like effectors (TALEs) from plant pathogenic Xanthomonas spp. and the related RipTALs from Ralstonia solanacearum are DNA-binding proteins with a modular DNA-binding domain. This domain is both predictable and programmable, which simplifies elucidation of TALE function in planta and facilitates generation of DNA-binding modules with desired specificity for biotechnological approaches. Recently identified TALE host target genes that either promote or stop bacterial disease provide new insights into how expression of TALE genes affects the plant–pathogen interaction. Since its elucidation the TALE code has been continuously refined and now provides a mature tool that, in combination with transcriptome profiling, allows rapid isolation of novel TALE target genes. The TALE code is also the basis for synthetic promoter-traps that mediate recognition of TALE or RipTAL proteins in engineered plants. In this review, we will summarize recent findings in plant-focused TALE research. In addition, we will provide an outline of the newly established gene isolation approach for TALE or RipTAL host target genes with an emphasis on potential pitfalls.


Via dromius, Kamoun Lab @ TSL
more...
No comment yet.
Rescooped by Jim Alfano from Plant-microbe interaction
Scoop.it!

Ca2+ signalling in plant immune response: from pattern recognition receptors to Ca2+ decoding mechanisms. - Seybold - 2014 - New Phytologist - Wiley Online Library

Ca2+ signalling in plant immune response: from pattern recognition receptors to Ca2+ decoding mechanisms. - Seybold - 2014 - New Phytologist - Wiley Online Library | microbial pathogenesis and plant immunity | Scoop.it

Summary

Ca2+ is a ubiquitous second messenger for cellular signalling in various stresses and developmental processes. Here, we summarize current developments in the roles of Ca2+ during plant immunity responses. We discuss the early perception events preceding and necessary for triggering cellular Ca2+ fluxes, the potential Ca2+-permeable channels, the decoding of Ca2+ signals predominantly via Ca2+-dependent phosphorylation events and transcriptional reprogramming. To highlight the complexity of the cellular signal network, we briefly touch on the interplay between Ca2+-dependent signalling and selected major signalling mechanisms – with special emphasis on reactive oxygen species at local and systemic levels.


Via Suayib Üstün
more...
No comment yet.
Rescooped by Jim Alfano from Plants and Microbes
Scoop.it!

New Phytologist: Special Issue: Plants interacting with other organisms (October 2014)

New Phytologist: Special Issue: Plants interacting with other organisms (October 2014) | microbial pathogenesis and plant immunity | Scoop.it

Editorial

 

Plant interactions with other organisms: molecules, ecology and evolution

 

Commentary

 

Different shades of JAZ during plant growth and defense

 

Nutrient supply differentially alters the dynamics of co-infecting phytoviruses

 

Letters

 

From shade avoidance responses to plant performance at vegetation level: using virtual plant modelling as a tool
F. J. Bongers, J. B. Evers, N. P. R. Anten & R. Pierik

 

Review

 

Magical mystery tour: MLO proteins in plant immunity and beyond
J. Acevedo-Garcia, S. Kusch & R. Panstruga

 

The squeeze cell hypothesis for the activation of jasmonate synthesis in response to wounding

E. E. Farmer, D. Gasperini & I. F. Acosta

 

Lipochitooligosaccharide recognition: an ancient story
Y. Liang, K. Tóth, Y. Cao, K. Tanaka, C. Espinoza & G. Stacey

 

Herbivore-induced plant volatiles: targets, perception and unanswered questions
M. Heil

 

There’s no place like home? An exploration of the mechanisms behind plant litter–decomposer affinity in terrestrial ecosystems
A. T. Austin, L. Vivanco, A. González-Arzac & L. I. Pérez

 

Insect herbivore-associated organisms affect plant responses to herbivory
F. Zhu, E. H. Poelman & M. Dicke

 

When mutualism goes bad: density- dependent impacts of introduced bees on plant reproduction
M. A. Aizen, C. L. Morales, D. P. Vázquez, L. A. Garibaldi, A. Sáez & L. D. Harder

 

Insect and pathogen attack and resistance in maize and its wild ancestors, the teosintes
E. S. de Lange, D. Balmer, B. Mauch-Mani & T. C. J. Turlings

 

Full papers

 

Linking phytochrome to plant immunity: low red : far-red ratios increase Arabidopsis susceptibility to Botrytis cinerea by reducing the biosynthesis of indolic glucosinolates and camalexin
M. D. Cargnel, P. V. Demkura & C. L. Ballaré

 

To grow or defend? Low red : far-red ratios reduce jasmonate sensitivity in Arabidopsis seedlings by promoting DELLA degradation and increasing JAZ10 stability
M. Leone, M. M. Keller, I. Cerrudo & C. L. Ballaré

 

β-Glucosidase BGLU42 is a MYB72-dependent key regulator of rhizobacteria-induced systemic resistance and modulates iron deficiency responses in Arabidopsis roots
C. Zamioudis, J. Hanson & C. M. J. Pieterse

 

Deciphering the language of plant communication: volatile chemotypes of sagebrush
R. Karban, W. C. Wetzel, K. Shiojiri, S. Ishizaki, S. R. Ramirez & J. D. Blande

 

The context dependence of beneficiary feedback effects on benefactors in plant facilitation
C. Schöb, R. M. Callaway, F. Anthelme, R. W. Brooker, L. A. Cavieres, Z. Kikvidze, C. J. Lortie, R. Michalet, F. I. Pugnaire, S. Xiao, B. H. Cranston, M-C. García, N. R. Hupp, L. D. Llambí, E. Lingua, A. M. Reid, L. Zhao & B. J. Butterfield

 

Herbivore-mediated material fluxes in a northern deciduous forest under elevated carbon dioxide and ozone concentrations
T. D. Meehan, J. J. Couture, A. E. Bennett & R. L. Lindroth

 

Are plant–soil feedback responses explained by plant traits?
C. Baxendale, K. H. Orwin, F. Poly, T. Pommier & R. D. Bardgett

 

Environmental nutrient supply alters prevalence and weakens competitive interactions among coinfecting viruses
C. Lacroix, E. W. Seabloom & E. T. Borer


Via Kamoun Lab @ TSL
more...
No comment yet.
Rescooped by Jim Alfano from Effectors and Plant Immunity
Scoop.it!

Curr. Biol.: Type III secretion system (2014)

Curr. Biol.: Type III secretion system (2014) | microbial pathogenesis and plant immunity | Scoop.it

The type III secretion system (T3SS) is a membrane-embedded nanomachine found in several Gram-negative bacteria. Upon contact between bacteria and host cells, the syringe-like T3SS transfers proteins termed effectors from the bacterial cytosol to the cytoplasm or the plasma membrane of a single target cell. This is a major difference from secretion systems that merely release molecules into the extracellular milieu, where they act on potentially distant target cells expressing the relevant surface receptors. The syringe architecture is conserved at the structural and functional level and supports injection into a great variety of hosts and tissues. However, the pool of effectors is species specific and determines the outcome of the interaction, via modulation of target-cell function.

 

Andrea Puhar & Philippe J. Sansonetti


Via Nicolas Denancé
more...
No comment yet.
Scooped by Jim Alfano
Scoop.it!

Cell Host & Microbe: Nonsense-Mediated mRNA Decay Modulates Immune Receptor Levels to Regulate Plant Antibacterial Defense: Cell Host & Microbe

Cell Host & Microbe: Nonsense-Mediated mRNA Decay Modulates Immune Receptor Levels to Regulate Plant Antibacterial Defense: Cell Host & Microbe | microbial pathogenesis and plant immunity | Scoop.it
Highlights•Nonsense-mediated mRNA decay (NMD) prevents aberrant plant immune response activation•NMD posttranscriptionally regulates numerous TNL immune receptor transcripts•NMD is dampened upon pathogen infection as part of host-programmed immunity•Host-regulated NMD inhibition upon infection promotes disease resistance
more...
No comment yet.
Scooped by Jim Alfano
Scoop.it!

Unconventionally secreted effectors of two filamentous pathogens target plant salicylate biosynthesis : Nature Communications : Nature Publishing Group

Unconventionally secreted effectors of two filamentous pathogens target plant salicylate biosynthesis : Nature Communications : Nature Publishing Group | microbial pathogenesis and plant immunity | Scoop.it

Plant diseases caused by fungi and oomycetes pose an increasing threat to food security and ecosystem health worldwide. These filamentous pathogens, while taxonomically distinct, modulate host defense responses by secreting effectors, which are typically identified based on the presence of signal peptides. Here we show that Phytophthora sojae and Verticillium dahliae secrete isochorismatases (PsIsc1 and VdIsc1, respectively) that are required for full pathogenesis. PsIsc1 and VdIsc1 can suppress salicylate-mediated innate immunity in planta and hydrolyse isochorismate in vitro. A conserved triad of catalytic residues is essential for both functions. Thus, the two proteins are isochorismatase effectors that disrupt the plant salicylate metabolism pathway by suppressing its precursor. Furthermore, these proteins lack signal peptides, but exhibit characteristics that lead to unconventional secretion. Therefore, this secretion pathway is a novel mechanism for delivering effectors and might play an important role in host–pathogen interactions.

more...
No comment yet.