plant-pathogen interaction at the molecular level
127 views | +0 today
Follow
Your new post is loading...
Your new post is loading...
Rescooped by Joanna from Plant pathogens and pests
Scoop.it!

A novel method of transcriptome interpretation reveals a quantitative suppressive effect on tomato immune signaling by two domains in a single pathogen effector protein

A novel method of transcriptome interpretation reveals a quantitative suppressive effect on tomato immune signaling by two domains in a single pathogen effector protein | plant-pathogen interaction at the molecular level | Scoop.it
“ Background Effector proteins are translocated into host cells by plant-pathogens to undermine pattern-triggered immunity (PTI), the plant response to microbe-associated molecular patterns that interferes with the infection process. Individual effectors are found in variable repertoires where some constituents target the same pathways. The effector protein AvrPto from Pseudomonas syringae has a core domain (CD) and C-terminal domain (CTD) that each promotes bacterial growth and virulence in tomato. The individual contributions of each domain and whether they act redundantly is unknown. Results We use RNA-Seq to elucidate the contribution of the CD and CTD to the suppression of PTI in tomato leaves 6 h after inoculation. Unexpectedly, each domain alters transcript levels of essentially the same genes but to a different degree. This difference, when quantified, reveals that although targeting the same host genes, the two domains act synergistically. AvrPto has a relatively greater effect on genes whose expression is suppressed during PTI, and the effect on these genes appears to be diminished by saturation. Conclusions RNA-Seq profiles can be used to observe relative contributions of effector subdomains to PTI suppression. Our analysis shows the CD and CTD multiplicatively affect the same gene transcript levels with a greater relative impact on genes whose expression is suppressed during PTI. The higher degree of up-regulation versus down-regulation during PTI is plausibly an evolutionary adaptation against effectors that target immune signaling.”
Via Christophe Jacquet
more...
No comment yet.
Rescooped by Joanna from Plant immunity and legume symbiosis
Scoop.it!

Arabidopsis miR827 mediates post-transcriptional gene silencing of its ubiquitin E3 ligase target gene in the syncytium of the cyst nematode Heterodera schachtii to enhance susceptibility - Hewezi ...

Arabidopsis miR827 mediates post-transcriptional gene silencing of its ubiquitin E3 ligase target gene in the syncytium of the cyst nematode Heterodera schachtii to enhance susceptibility - Hewezi ... | plant-pathogen interaction at the molecular level | Scoop.it
“ MicroRNAs (miRNAs) are a major class of small non-coding RNAs with emerging functions in biotic and abiotic interactions. Here, we report on a new functional role of Arabidopsis miR827 and its NITROGEN LIMITATION ADAPTATION (NLA) target gene in mediating plant susceptibility to the beet cyst nematode Heterodera schachtii. Cyst nematodes are sedentary endoparasites that induce the formation of multinucleated feeding structures termed syncytia in the roots of host plants. Using promoter:GUS fusion assays we established that miR827 was activated in the initial feeding cells and this activation was maintained in the syncytium during all sedentary stages of nematode development. Meanwhile, the NLA target gene, which encodes an ubiquitin E3 ligase enzyme, was post-transcriptionally silenced in the syncytium to permanently suppress its activity during all nematode parasitic stages. Overexpression of miR827 in Arabidopsis resulted in hyper-susceptibility to H. schachtii. In contrast, inactivation of miR827 activity through target mimicry or by overexpression a miR827-resistant cDNA of NLA produced the opposite phenotype of reduced plant susceptibility to H. schachtii. Gene expression analysis of several pathogenesis-related genes together with Agrobacterium-mediated transient expression in Nicotiana benthamiana provided strong evidence that miR827-mediated downregulation of NLA to suppress basal defense pathways. In addition, using yeast two-hybrid screens we identified several candidates of NLA-interacting proteins that are involved in a wide range of biological processes and molecular functions, including three pathogenesis-related proteins. Taken together, we conclude that nematode-activated miR827 in the syncytium is necessary to suppress immune responses in order to establish infection and cause disease.”
Via Christophe Jacquet
more...
No comment yet.
Rescooped by Joanna from Plant immunity and legume symbiosis
Scoop.it!

Should I fight or should I grow now? The role of cytokinins in plant growth and immunity and in the growth–defence trade-off

Should I fight or should I grow now? The role of cytokinins in plant growth and immunity and in the growth–defence trade-off | plant-pathogen interaction at the molecular level | Scoop.it
“ Background Perception and activation of plant immunity require a remarkable level of signalling plasticity and control. In Arabidopsis and other plant species, constitutive defence activation leads to resistance to a broad spectrum of biotrophic pathogens, but also frequently to stunted growth and reduced seed set. Plant hormones are important integrators of the physiological responses that influence the outcome of plant–pathogen interactions. Scope We review the mechanisms by which the plant hormone cytokinin regulates both plant growth and response to pathogens, and how cytokinins may connect these two processes, ultimately affecting the growth trade-offs observed in plant immunity.”
Via Christophe Jacquet
more...
No comment yet.
Rescooped by Joanna from Plant-microbe interaction
Scoop.it!

bioRxiv: NLR signaling network mediates immunity to diverse plant pathogens (2016)

bioRxiv: NLR signaling network mediates immunity to diverse plant pathogens (2016) | plant-pathogen interaction at the molecular level | Scoop.it

Plant and animal nucleotide-binding domain and leucine-rich repeat-containing (NLR) proteins often function in pairs to mediate innate immunity to pathogens. However, the degree to which NLR proteins form signaling networks beyond genetically linked pairs is poorly understood. In this study, we discovered that a large NLR immune signaling network with a complex genetic architecture confers immunity to oomycetes, bacteria, viruses, nematodes, and insects. The network emerged over 100 million years ago from a linked NLR pair that diversified into up to one half of the NLR of asterid plants. We propose that this NLR network increases robustness of immune signaling to counteract rapidly evolving plant pathogens.


Via Kamoun Lab @ TSL, Suayib Üstün
more...
No comment yet.
Rescooped by Joanna from Plant pathology
Scoop.it!

Current Opinion in Microbiology: The cell biology of late blight disease (2016)

Current Opinion in Microbiology: The cell biology of late blight disease (2016) | plant-pathogen interaction at the molecular level | Scoop.it

• The Phytophthora haustorium is a major site of secretion during infection.

• The host endocytic cycle contributes to biogenesis of the Extra-Haustorial Membrane. • RXLR effectors manipulate host processes at diverse subcellular locations.

• They directly manipulate the activity or location of immune proteins.

• They also promote the activity of endogenous negative regulators of immunity.

Late blight, caused by the oomycete Phytophthora infestans, is a major global disease of potato and tomato. Cell biology is teaching us much about the developmental stages associated with infection, especially the haustorium, which is a site of intimate interaction and molecular exchange between pathogen and host. Recent observations suggest a role for the plant endocytic cycle in specific recruitment of host proteins to the Extra-Haustorial Membrane, emphasising the unique nature of this membrane compartment. In addition, there has been a strong focus on the activities of RXLR effectors, which are delivered into plant cells to modulate and manipulate host processes. RXLR effectors interact directly with diverse plant proteins at a range of subcellular locations to promote disease.


Via Kamoun Lab @ TSL, fundoshi
more...
No comment yet.
Rescooped by Joanna from microbial pathogenesis and plant immunity
Scoop.it!

New Phytologist: Nine things to know about elicitins (2016)

New Phytologist: Nine things to know about elicitins (2016) | plant-pathogen interaction at the molecular level | Scoop.it

Elicitins are structurally conserved extracellular proteins in Phytophthora and Pythium oomycete pathogen species. They were first described in the late 1980s as abundant proteins in Phytophthora culture filtrates that have the capacity to elicit hypersensitive (HR) cell death and disease resistance in tobacco. Later, they became well-established as having features of microbe-associated molecular patterns (MAMPs) and to elicit defences in a variety of plant species. Research on elicitins culminated in the recent cloning of the elicitin response (ELR) cell surface receptor-like protein, from the wild potato Solanum microdontum, which mediates response to a broad range of elicitins. In this review, we provide an overview on elicitins and the plant responses they elicit. We summarize the state of the art by describing what we consider to be the nine most important features of elicitin biology.


Via Kamoun Lab @ TSL, Jim Alfano
more...
No comment yet.
Rescooped by Joanna from Plant immunity and legume symbiosis
Scoop.it!

Salicylic acid receptors activate jasmonic acid signalling through a non-canonical pathway to promote effector-triggered immunity

Salicylic acid receptors activate jasmonic acid signalling through a non-canonical pathway to promote effector-triggered immunity | plant-pathogen interaction at the molecular level | Scoop.it
“ It is an apparent conundrum how plants evolved effector-triggered immunity (ETI), involving programmed cell death (PCD), as a major defence mechanism against biotrophic pathogens, because ETI-associated PCD could leave them vulnerable to necrotrophic pathogens that thrive on dead host cells. Interestingly, during ETI, the normally antagonistic defence hormones, salicylic acid (SA) and jasmonic acid (JA) associated with defence against biotrophs and necrotrophs respectively, both accumulate to high levels. In this study, we made the surprising finding that JA is a positive regulator of RPS2-mediated ETI. Early induction of JA-responsive genes and de novo JA synthesis following SA accumulation is activated through the SA receptors NPR3 and NPR4, instead of the JA receptor COI1. We provide evidence that NPR3 and NPR4 may mediate this effect by promoting degradation of the JA transcriptional repressor JAZs. This unique interplay between SA and JA offers a possible explanation of how plants can mount defence against a biotrophic pathogen without becoming vulnerable to necrotrophic pathogens.”
Via Francis Martin, Jim Alfano, Suayib Üstün, Christophe Jacquet
more...
No comment yet.
Rescooped by Joanna from Plant Pathology
Scoop.it!

Current Opinion in Microbiology: The cell biology of late blight disease (2016)

Current Opinion in Microbiology: The cell biology of late blight disease (2016) | plant-pathogen interaction at the molecular level | Scoop.it

• The Phytophthora haustorium is a major site of secretion during infection.

• The host endocytic cycle contributes to biogenesis of the Extra-Haustorial Membrane.• RXLR effectors manipulate host processes at diverse subcellular locations.

• They directly manipulate the activity or location of immune proteins.

• They also promote the activity of endogenous negative regulators of immunity.

Late blight, caused by the oomycete Phytophthora infestans, is a major global disease of potato and tomato. Cell biology is teaching us much about the developmental stages associated with infection, especially the haustorium, which is a site of intimate interaction and molecular exchange between pathogen and host. Recent observations suggest a role for the plant endocytic cycle in specific recruitment of host proteins to the Extra-Haustorial Membrane, emphasising the unique nature of this membrane compartment. In addition, there has been a strong focus on the activities of RXLR effectors, which are delivered into plant cells to modulate and manipulate host processes. RXLR effectors interact directly with diverse plant proteins at a range of subcellular locations to promote disease.


Via Kamoun Lab @ TSL, Rey Thomas, Kihyuck Choi
more...
No comment yet.
Rescooped by Joanna from Microbiome and plant immunity
Scoop.it!

The 7 biggest problems facing science, according to 270 scientists

The 7 biggest problems facing science, according to 270 scientists | plant-pathogen interaction at the molecular level | Scoop.it
“ These are dark times for science so we asked hundreds of researchers how to fix it.”
Via Niklaus Grunwald, Rey Thomas, Giannis Stringlis
more...
No comment yet.
Rescooped by Joanna from Microbiome and plant immunity
Scoop.it!

New Phytologist: Nine things to know about elicitins (2016)

New Phytologist: Nine things to know about elicitins (2016) | plant-pathogen interaction at the molecular level | Scoop.it

Elicitins are structurally conserved extracellular proteins in Phytophthora and Pythium oomycete pathogen species. They were first described in the late 1980s as abundant proteins in Phytophthora culture filtrates that have the capacity to elicit hypersensitive (HR) cell death and disease resistance in tobacco. Later, they became well-established as having features of microbe-associated molecular patterns (MAMPs) and to elicit defences in a variety of plant species. Research on elicitins culminated in the recent cloning of the elicitin response (ELR) cell surface receptor-like protein, from the wild potato Solanum microdontum, which mediates response to a broad range of elicitins. In this review, we provide an overview on elicitins and the plant responses they elicit. We summarize the state of the art by describing what we consider to be the nine most important features of elicitin biology.


Via Kamoun Lab @ TSL, Jim Alfano, Giannis Stringlis
more...
No comment yet.
Rescooped by Joanna from microbial pathogenesis and plant immunity
Scoop.it!

The proteasome acts as a hub for plant immunity and is targeted by Pseudomonas type-III effectors

The proteasome acts as a hub for plant immunity and is targeted by Pseudomonas type-III effectors | plant-pathogen interaction at the molecular level | Scoop.it
“ Recent evidence suggests that the ubiquitin-proteasome system (UPS) is involved in several aspects of plant immunity and a range of plant pathogens subvert the UPS to enhance their virulence. Here we show that proteasome activity is strongly induced during basal defense in Arabidopsis. Mutant lines of the proteasome subunits RPT2a and RPN12a support increased bacterial growth of virulent Pseudomonas syringae pv. tomato DC3000 (Pst) and Pseudomonas syringae pv. maculicola ES4326. Both proteasome subunits are required for Pathogen-associated molecular patterns (PAMP)-triggered immunity (PTI) responses. Analysis of bacterial growth after a secondary infection of systemic leaves revealed that the establishment of systemic-acquired resistance (SAR) is impaired in proteasome mutants, suggesting that the proteasome also plays an important role in defense priming and SAR. In addition, we show that Pst inhibits proteasome activity in a type-III secretion dependent manner. A screen for type-III effector proteins from Pst for their ability to interfere with proteasome activity revealed HopM1, HopAO1, HopA1 and HopG1 as putative proteasome inhibitors. Biochemical characterization of HopM1 by mass-spectrometry indicates that HopM1 interacts with several E3 ubiquitin ligases and proteasome subunits. This supports the hypothesis that HopM1 associates with the proteasome leading to its inhibition. Thus, the proteasome is an essential component of PTI and SAR, which is targeted by multiple bacterial effectors. ”

Via Suayib Üstün, Jim Alfano
more...
No comment yet.
Rescooped by Joanna from Plant immunity and legume symbiosis
Scoop.it!

Frontiers | Role of Ubiquitin-Mediated Degradation System in Plant Biology

Frontiers | Role of Ubiquitin-Mediated Degradation System in Plant Biology | plant-pathogen interaction at the molecular level | Scoop.it
“ Ubiquitin-mediated proteasomal degradation is an important mechanism to control protein load in the cells. Ubiquitin binds to a protein on lysine residue and usually promotes its degradation through 26S proteasome system. Abnormal proteins and regulators of many processes, are targeted for degradation by the ubiquitin-proteasome system. It allows cells to maintain the response to cellular level signals and altered environmental conditions. The ubiquitin-mediated proteasomal degradation system plays a key role in the plant biology, including abiotic stress, immunity, and hormonal signaling by interfering with key components of these pathways. The involvement of the ubiquitin system in many vital processes led scientists to explore more about the ubiquitin machinery and most importantly its targets. In this review, we have summarized recent discoveries of the plant ubiquitin system and its involvement in critical processes of plant biology.”
Via Christophe Jacquet
more...
No comment yet.
Rescooped by Joanna from Plant Pathogens
Scoop.it!

Structure-informed insights for NLR functioning in plant immunity

Structure-informed insights for NLR functioning in plant immunity | plant-pathogen interaction at the molecular level | Scoop.it
“ To respond to foreign invaders, plants have evolved a cell autonomous multilayered immune system consisting of extra- and intracellular immune receptors. Nucleotide binding and oligomerization domain (NOD)-like receptors (NLRs) mediate recognition of pathogen effectors inside the cell and trigger a host specific defense response, often involving controlled cell death. NLRs consist of a central nucleotide-binding domain, which is flanked by an N-terminal CC or TIR domain and a C-terminal leucine-rich repeat domain (LRR). These multidomain proteins function as a molecular switch and their activity is tightly controlled by intra and inter-molecular interactions. In contrast to metazoan NLRs, the structural basis underlying NLR functioning as a pathogen sensor and activator of immune responses in plants is largely unknown. However, the first crystal structures of a number of plant NLR domains were recently obtained. In addition, biochemical and structure-informed analyses revealed novel insights in the cooperation between NLR domains and the formation of pre- and post activation complexes, including the coordinated activity of NLR pairs as pathogen sensor and executor of immune responses. Moreover, the discovery of novel integrated domains underscores the structural diversity of NLRs and provides alternative models for how these immune receptors function in plants. In this review, we will highlight these recent advances to provide novel insights in the structural, biochemical and molecular aspects involved in plant NLR functioning.”
Via Elsa Ballini, Yogesh Gupta
more...
Elsa Ballini's curator insight, August 5, 9:08 AM
Detection of an elicitor by sensor NLRs has in some cases, been reported to occur by direct physical binding. In both RGA4/RGA5 and Pik-2/Pik-1 CNL pairs from rice, a direct interaction between the Magnaporthae effector and the HMA (Heavy-Metal Associated Domain) is required for receptor activation [127] and [128]. In Pik-1 the HMA domain is integrated between the CC and NB-ARC domain and in RGA5 it is integrated C-terminal to the LRR. A crystal structure of the Pikp-1 HMA and Avr-PikD complex shows how characteristics of the integrated HMA domain determine recognition specificity of the Pik-1/Pik-2 pair for the Magnaporthae AvrPik effectors
Rescooped by Joanna from microbial pathogenesis and plant immunity
Scoop.it!

Dying two deaths — programmed cell death regulation in development and disease

Dying two deaths — programmed cell death regulation in development and disease | plant-pathogen interaction at the molecular level | Scoop.it

Via Tatsuya Nobori, Jim Alfano
more...
No comment yet.
Rescooped by Joanna from Plant pathogens and pests
Scoop.it!

Nature: Bacteria establish an aqueous living space in plants crucial for virulence (2016)

Nature: Bacteria establish an aqueous living space in plants crucial for virulence (2016) | plant-pathogen interaction at the molecular level | Scoop.it

High humidity has a strong influence on the development of numerous diseases affecting the above-ground parts of plants (the phyllosphere) in crop fields and natural ecosystems, but the molecular basis of this humidity effect is not understood. Previous studies have emphasized immune suppression as a key step in bacterial pathogenesis. Here we show that humidity-dependent, pathogen-driven establishment of an aqueous intercellular space (apoplast) is another important step in bacterial infection of the phyllosphere. Bacterial effectors, such as Pseudomonas syringae HopM1, induce establishment of the aqueous apoplast and are sufficient to transform non-pathogenic P. syringae strains into virulent pathogens in immunodeficient Arabidopsis thaliana under high humidity. Arabidopsis quadruple mutants simultaneously defective in a host target (AtMIN7) of HopM1 and in pattern-triggered immunity could not only be used to reconstitute the basic features of bacterial infection, but also exhibited humidity-dependent dyshomeostasis of the endophytic commensal bacterial community in the phyllosphere. These results highlight a new conceptual framework for understanding diverse phyllosphere–bacterial interactions.


Via Kamoun Lab @ TSL, Christophe Jacquet
more...
No comment yet.
Rescooped by Joanna from Plant immunity and legume symbiosis
Scoop.it!

The sterol‐binding activity of PATHOGENESIS‐RELATED PROTEIN 1 reveals the mode of action of an antimicrobial protein

The sterol‐binding activity of PATHOGENESIS‐RELATED PROTEIN 1 reveals the mode of action of an antimicrobial protein | plant-pathogen interaction at the molecular level | Scoop.it
“ Pathogenesis-related proteins played a pioneering role fifty years ago in the discovery of plant innate immunity as a set of proteins that accumulated upon pathogen challenge. The most abundant of these proteins, PATHOGENESIS-RELATED 1 (PR-1) encodes a small antimicrobial protein that has become, as a marker of plant immune signaling, one of the most referred to plant proteins. However, the biochemical activity and mode of action of PR-1 proteins has remained elusive. Here, we provide genetic and biochemical evidence for the capacity of PR-1 proteins to bind sterols and demonstrate that the inhibitory effect on pathogen growth is caused by sterol sequestration from pathogens. In support of our findings, sterol-auxotroph pathogens such as the oomycete Phytophthora are particularly sensitive to PR-1 whereas sterol-prototroph fungal pathogens become highly sensitive only when sterol-biosynthesis is compromised. Our results are in line with previous findings showing that plants with enhanced PR-1 expression are particularly well protected against oomycete pathogens.”
Via Christophe Jacquet
more...
No comment yet.
Rescooped by Joanna from Plant immunity and legume symbiosis
Scoop.it!

An E3 Ligase Affects the NLR Receptor Stability and Immunity to Powdery Mildew

An E3 Ligase Affects the NLR Receptor Stability and Immunity to Powdery Mildew | plant-pathogen interaction at the molecular level | Scoop.it
“ Following the detection of pathogen cognate effectors, plant Nod-like receptors (NLRs) trigger isolate-specific immunity that is generally associated with cell death. The regulation of NLR stability is important to ensure effective immunity. In barley (Hordeum vulgare), the allelic Mildew locus A (MLA) receptors mediate isolate-specific disease resistance against powdery mildew fungus (Blumeria graminis f. sp. hordei). Currently, how MLA stability is controlled remains unknown. Here, we identified an MLA-interacting RING-type E3 ligase, MIR1, that interacts with several MLAs. We showed that the carboxyl-terminal TPR domain of MIR1 mediates the interaction with the coiled-coil domain-containing region of functional MLAs, such as MLA1, MLA6, and MLA10, but not with that of the nonfunctional MLA18-1. MIR1 can ubiquitinate the amino-terminal region of MLAs in vitro and promotes the proteasomal degradation of MLAs in vitro and in planta. Both proteasome inhibitor treatment and virus-induced gene silencing-mediated MIR1 silencing significantly increased MLA abundance in barley transgenic lines. Furthermore, overexpression of MIR1 specifically compromised MLA-mediated disease resistance in barley, while coexpression of MIR1 and MLA10 attenuated MLA10-induced cell death signaling in Nicotiana benthamiana. Together, our data reveal a mechanism for the control of the stability of MLA immune receptors and for the attenuation of MLA-triggered defense signaling by a RING-type E3 ligase via the ubiquitin proteasome system.”
Via Christophe Jacquet
more...
No comment yet.
Rescooped by Joanna from Plant Pathology
Scoop.it!

Current Opinion in Microbiology: The cell biology of late blight disease (2016)

Current Opinion in Microbiology: The cell biology of late blight disease (2016) | plant-pathogen interaction at the molecular level | Scoop.it

• The Phytophthora haustorium is a major site of secretion during infection.

• The host endocytic cycle contributes to biogenesis of the Extra-Haustorial Membrane.• RXLR effectors manipulate host processes at diverse subcellular locations.

• They directly manipulate the activity or location of immune proteins.

• They also promote the activity of endogenous negative regulators of immunity.

Late blight, caused by the oomycete Phytophthora infestans, is a major global disease of potato and tomato. Cell biology is teaching us much about the developmental stages associated with infection, especially the haustorium, which is a site of intimate interaction and molecular exchange between pathogen and host. Recent observations suggest a role for the plant endocytic cycle in specific recruitment of host proteins to the Extra-Haustorial Membrane, emphasising the unique nature of this membrane compartment. In addition, there has been a strong focus on the activities of RXLR effectors, which are delivered into plant cells to modulate and manipulate host processes. RXLR effectors interact directly with diverse plant proteins at a range of subcellular locations to promote disease.


Via Kamoun Lab @ TSL, Rey Thomas, Kihyuck Choi
more...
No comment yet.
Rescooped by Joanna from Plant Pathogens
Scoop.it!

Immunity to Rice Blast Disease by Suppression of Effector-Triggered Necrosis

Immunity to Rice Blast Disease by Suppression of Effector-Triggered Necrosis | plant-pathogen interaction at the molecular level | Scoop.it
“ Highlights •AvrPiz-t interacts and co-localizes with APIP5 in the cytoplasm •AvrPiz-t suppresses APIP5 transcriptional activity and protein accumulation •APIP5, a negative regulator of cell death, interacts with the NLR receptor Piz-t •Piz-t suppresses the AvrPiz-t-mediated APIP5 turnover Summary Hemibiotrophic pathogens are some of the most destructive plant pathogens, causing huge economic losses and threatening global food security. Infection with these organisms often involves an initial biotrophic infection phase, during which the pathogen spreads in host tissue asymptomatically, followed by a necrotrophic phase, during which host-cell death is induced. How hemibiotrophic pathogens trigger host necrosis and how plants inhibit the transition from the biotrophic stage to the necrotrophic stage in disease symptom expression are mainly unknown. The rice blast fungus Magnaporthe oryzae spreads in rice biotrophically early during infection, but this biotrophic stage is followed by a pronounced switch to cell death and lesion formation. Here, we show that the M. oryzae effector AvrPiz-t interacts with the bZIP-type transcription factor APIP5 in the cytoplasm and suppresses its transcriptional activity and protein accumulation at the necrotrophic stage. Silencing of APIP5 in transgenic rice leads to cell death, and the phenotype is enhanced by the expression of AvrPiz-t. Conversely, Piz-t interacts with and stabilizes APIP5 to prevent necrosis at the necrotrophic stage. At the same time, APIP5 is essential for Piz-t stability. These results demonstrate a novel mechanism for the suppression of effector-triggered necrosis at the necrotrophic stage by an NLR receptor in plants.”
Via Christophe Jacquet, Yogesh Gupta
more...
No comment yet.
Rescooped by Joanna from Plant immunity and legume symbiosis
Scoop.it!

The proteasome acts as a hub for plant immunity and is targeted by Pseudomonas type-III effectors

The proteasome acts as a hub for plant immunity and is targeted by Pseudomonas type-III effectors | plant-pathogen interaction at the molecular level | Scoop.it
“ Recent evidence suggests that the ubiquitin-proteasome system (UPS) is involved in several aspects of plant immunity and a range of plant pathogens subvert the UPS to enhance their virulence. Here we show that proteasome activity is strongly induced during basal defense in Arabidopsis. Mutant lines of the proteasome subunits RPT2a and RPN12a support increased bacterial growth of virulent Pseudomonas syringae pv. tomato DC3000 (Pst) and Pseudomonas syringae pv. maculicola ES4326. Both proteasome subunits are required for Pathogen-associated molecular patterns (PAMP)-triggered immunity (PTI) responses. Analysis of bacterial growth after a secondary infection of systemic leaves revealed that the establishment of systemic-acquired resistance (SAR) is impaired in proteasome mutants, suggesting that the proteasome also plays an important role in defense priming and SAR. In addition, we show that Pst inhibits proteasome activity in a type-III secretion dependent manner. A screen for type-III effector proteins from Pst for their ability to interfere with proteasome activity revealed HopM1, HopAO1, HopA1 and HopG1 as putative proteasome inhibitors. Biochemical characterization of HopM1 by mass-spectrometry indicates that HopM1 interacts with several E3 ubiquitin ligases and proteasome subunits. This supports the hypothesis that HopM1 associates with the proteasome leading to its inhibition. Thus, the proteasome is an essential component of PTI and SAR, which is targeted by multiple bacterial effectors.”
Via Suayib Üstün, Christophe Jacquet
more...
No comment yet.
Rescooped by Joanna from microbial pathogenesis and plant immunity
Scoop.it!

Behind the lines–actions of bacterial type III effector proteins in plant cells

Behind the lines–actions of bacterial type III effector proteins in plant cells | plant-pathogen interaction at the molecular level | Scoop.it
“ Pathogenicity of most Gram-negative plant-pathogenic bacteria depends on the type III secretion (T3S) system, which translocates bacterial effector proteins into plant cells. Type III effectors modulate plant cellular pathways to the benefit of the pathogen and promote bacterial multiplication. One major virulence function of type III effectors is the suppression of plant innate immunity, which is triggered upon recognition of pathogen-derived molecular patterns by plant receptor proteins. Type III effectors also interfere with additional plant cellular processes including proteasome-dependent protein degradation, phytohormone signaling, the formation of the cytoskeleton, vesicle transport and gene expression. This review summarizes our current knowledge on the molecular functions of type III effector proteins with known plant target molecules. Furthermore, plant defense strategies for the detection of effector protein activities or effector-triggered alterations in plant targets are discussed. ”

Via Suayib Üstün, Jim Alfano
more...
Suayib Üstün's comment, August 20, 5:38 AM
really great review!
Rescooped by Joanna from microbial pathogenesis and plant immunity
Scoop.it!

Regulation of pattern recognition receptor signalling in plants : Nature Reviews Immunology : Nature Research

Regulation of pattern recognition receptor signalling in plants : Nature Reviews Immunology : Nature Research | plant-pathogen interaction at the molecular level | Scoop.it
Recognition of pathogen-derived molecules by pattern recognition receptors (PRRs) is a common feature of both animal and plant innate immune systems. In plants, PRR signalling is initiated at the cell surface by kinase complexes, resulting in the activation of immune responses that ward off microorganisms. However, the activation and amplitude of innate immune responses must be tightly controlled. In this Review, we summarize our knowledge of the early signalling events that follow PRR activation and describe the mechanisms that fine-tune immune signalling to maintain immune homeostasis. We also illustrate the mechanisms used by pathogens to inhibit innate immune signalling and discuss how the innate ability of plant cells to monitor the integrity of key immune components can lead to autoimmune phenotypes following genetic or pathogen-induced perturbations of these components.

Via Giannis Stringlis, Jim Alfano
more...
No comment yet.
Rescooped by Joanna from Microbiome and plant immunity
Scoop.it!

How not to respond to reviewers: Eight simple tips

How not to respond to reviewers: Eight simple tips | plant-pathogen interaction at the molecular level | Scoop.it
“ My first attempt at publishing a paper was a breeze. A collaborator was asked to contribute to a special issue and offered me the opportunity to lead the paper. I was a PhD student at the time, and spent two months visiting her lab overseas and writing. By the end of my visit, I’d carved out a draft that I left behind for comments. After a bunch of emails and several rounds of revisions over the next month, we were ready to submit. ”
Via Jean-Michel Ané, Giannis Stringlis
more...
No comment yet.
Rescooped by Joanna from Plant pathology
Scoop.it!

BioEssays: Pathogen perception by NLRs in plants and animals: Parallel worlds (2016)

BioEssays: Pathogen perception by NLRs in plants and animals: Parallel worlds (2016) | plant-pathogen interaction at the molecular level | Scoop.it

Via The Sainsbury Lab, fundoshi
more...
The Sainsbury Lab's curator insight, June 27, 4:40 AM
Intracellular NLR (Nucleotide-binding domain and Leucine-rich Repeat-containing) receptors are sensitive monitors that detect pathogen invasion of both plant and animal cells. NLRs confer recognition of diverse molecules associated with pathogen invasion. NLRs must exhibit strict intramolecular controls to avoid harmful ectopic activation in the absence of pathogens. Recent discoveries have elucidated the assembly and structure of oligomeric NLR signalling complexes in animals, and provided insights into how these complexes act as scaffolds for signal transduction. In plants, recent advances have provided novel insights into signalling-competent NLRs, and into the myriad strategies that diverse plant NLRs use to recognise pathogens. Here, we review recent insights into the NLR biology of both animals and plants. By assessing commonalities and differences between kingdoms, we are able to develop a more complete understanding of NLR function.
Rescooped by Joanna from Plant immunity and legume symbiosis
Scoop.it!

DNA Methylation and Demethylation in Plant Immunity - Annual Review of Phytopathology,

DNA Methylation and Demethylation in Plant Immunity - Annual Review of Phytopathology, | plant-pathogen interaction at the molecular level | Scoop.it
“ Detection of plant and animal pathogens triggers a massive transcriptional reprogramming, which is directed by chromatin-based processes, and ultimately results in antimicrobial immunity. Although the implication of histone modifications in orchestrating biotic stress–induced transcriptional reprogramming has been well characterized, very little was known, until recently, about the role of DNA methylation and demethylation in this process. In this review, we summarize recent findings on the dynamics and biological relevance of DNA methylation and demethylation in plant immunity against nonviral pathogens. In particular, we report the implications of these epigenetic regulatory processes in the transcriptional and co-transcriptional control of immune-responsive genes and discuss their relevance in fine-tuning antimicrobial immune responses. Finally, we discuss the possible yet elusive role of DNA methylation and demethylation in systemic immune responses, transgenerational immune priming, and de novo epiallelism, which could be adaptive.”
Via Christophe Jacquet
more...
No comment yet.