microbial pathogenesis and plant immunity
11.1K views | +0 today
Follow
microbial pathogenesis and plant immunity
Your new post is loading...
Your new post is loading...
Rescooped by Jim Alfano from Plants and Microbes
Scoop.it!

Plant Cell: Plants Release Precursors of Histone Deacetylase Inhibitors to Suppress Growth of Competitors (2015)

Plant Cell: Plants Release Precursors of Histone Deacetylase Inhibitors to Suppress Growth of Competitors (2015) | microbial pathogenesis and plant immunity | Scoop.it

To secure their access to water, light, and nutrients, many plant species have developed allelopathic strategies to suppress competitors. To this end, they release into the rhizosphere phytotoxic substances that inhibit the germination and growth of neighbors. Despite the importance of allelopathy in shaping natural plant communities and for agricultural production, the underlying molecular mechanisms are largely unknown. Here, we report that allelochemicals derived from the common class of cyclic hydroxamic acid root exudates directly affect the chromatin-modifying machinery in Arabidopsis thaliana. These allelochemicals inhibit histone deacetylases both in vitro and in vivo and exert their activity through locus-specific alterations of histone acetylation and associated gene expression. Our multilevel analysis collectively shows how plant-plant interactions interfere with a fundamental cellular process, histone acetylation, by targeting an evolutionarily highly conserved class of enzymes.


Via Kamoun Lab @ TSL
more...
No comment yet.
Rescooped by Jim Alfano from Host-Microbe Interactions. Plant Biology.
Scoop.it!

Microbiota Diurnal Rhythmicity Programs Host Transcriptome Oscillations 

Microbiota Diurnal Rhythmicity Programs Host Transcriptome Oscillations  | microbial pathogenesis and plant immunity | Scoop.it

Via Tatsuya Nobori
more...
No comment yet.
Rescooped by Jim Alfano from Microbiome and plant immunity
Scoop.it!

The Plant Microbiota: Systems-Level Insights and Perspectives - Annual Review of Genetics, 50(1):211

The Plant Microbiota: Systems-Level Insights and Perspectives - Annual Review of Genetics, 50(1):211 | microbial pathogenesis and plant immunity | Scoop.it
Plants do not grow as axenic organisms in nature, but host a diverse community of microorganisms, termed the plant microbiota. There is an increasing awareness that the plant microbiota plays a role in plant growth and can provide protection from invading pathogens. Apart from intense research on crop plants, Arabidopsis is emerging as a valuable model system to investigate the drivers shaping stable bacterial communities on leaves and roots and as a tool to decipher the intricate relationship among the host and its colonizing microorganisms. Gnotobiotic experimental systems help establish causal relationships between plant and microbiota genotypes and phenotypes and test hypotheses on biotic and abiotic perturbations in a systematic way. We highlight major recent findings in plant microbiota research using comparative community profiling and omics analyses, and discuss these approaches in light of community establishment and beneficial traits like nutrient acquisition and plant health.

Via Giannis Stringlis
more...
No comment yet.
Rescooped by Jim Alfano from The Plant Microbiome
Scoop.it!

Plant domestication and the assembly of bacterial and fungal communities associated with strains of the common sunflower, Helianthus annuus

Plant domestication and the assembly of bacterial and fungal communities associated with strains of the common sunflower, Helianthus annuus | microbial pathogenesis and plant immunity | Scoop.it
Root and rhizosphere microbial communities can affect plant health, but it remains undetermined how plant domestication may influence these bacterial and fungal communities. We grew 33 sunflower (Helianthus annuus) strains (n = 5) that varied in their extent of domestication and assessed rhizosphere and root endosphere bacterial and fungal communities. We also assessed fungal communities in the sunflower seeds to investigate the degree to which root and rhizosphere communities were influenced by vertical transmission of the microbiome through seeds. Neither root nor rhizosphere bacterial communities were affected by the extent of sunflower domestication, but domestication did affect the composition of rhizosphere fungal communities. In particular, more modern sunflower strains had lower relative abundances of putative fungal pathogens. Seed-associated fungal communities strongly differed across strains, but several lines of evidence suggest that there is minimal vertical transmission of fungi from seeds to the adult plants. Our results indicate that plant-associated fungal communities are more strongly influenced by host genetic factors and plant breeding than bacterial communities, a finding that could influence strategies for optimizing microbial communities to improve crop yields.

Via Stéphane Hacquard
more...
Back to the Roots 's curator insight, November 28, 6:12 AM
Impact of domestication in Helianthus annuus.
Rescooped by Jim Alfano from Plants and Microbes
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) | microbial pathogenesis and plant immunity | 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
more...
No comment yet.
Rescooped by Jim Alfano from Host-Microbe Interactions. Plant Biology.
Scoop.it!

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

Dying two deaths — programmed cell death regulation in development and disease | microbial pathogenesis and plant immunity | Scoop.it

Via Tatsuya Nobori
more...
No comment yet.
Rescooped by Jim Alfano from Plant-Microbe Symbiosis
Scoop.it!

Recent Developments in Systems Biology and Metabolic Engineering of Plant–Microbe Interactions

Recent Developments in Systems Biology and Metabolic Engineering of Plant–Microbe Interactions | microbial pathogenesis and plant immunity | Scoop.it
Microorganisms play a crucial role in the sustainability of the various ecosystems. The characterization of various interactions between microorganisms and other biotic factors is a necessary footstep to understand the association and functions of microbial communities. Among the different microbial interactions in an ecosystem, plant–microbe interaction plays an important role to balance the ecosystem. The present review explores plant–microbe interactions using gene editing and system biology tools toward the comprehension in improvement of plant traits. Further, system biology tools like FBA (flux balance analysis), OptKnock, and constraint-based modeling helps in understanding such interactions as a whole. In addition, various gene editing tools have been summarized and a strategy has been hypothesized for the development of disease free plants. Furthermore, we have tried to summarize the predictions through data retrieved from various types of sources such as high throughput sequencing data (e.g., single nucleotide polymorphism detection, RNA-seq, proteomics) and metabolic models have been reconstructed from such sequences for species communities. It is well known fact that systems biology approaches and modeling of biological networks will enable us to learn the insight of such network and will also help further in understanding these interactions.


Via Jean-Michel Ané
more...
Herve Moal's curator insight, November 11, 3:42 AM

Toute la complexité de l'écologie et de la botanique

Rescooped by Jim Alfano from Host-Microbe Interactions. Plant Biology.
Scoop.it!

The hijacking of a receptor kinase–driven pathway by a wheat fungal pathogen leads to disease

The hijacking of a receptor kinase–driven pathway by a wheat fungal pathogen leads to disease | microbial pathogenesis and plant immunity | Scoop.it
Necrotrophic pathogens live and feed on dying tissue, but their interactions with plants are not well understood compared to biotrophic pathogens. The wheat Snn1 gene confers susceptibility to strains of the necrotrophic pathogen Parastagonospora nodorum that produce the SnTox1 protein. We report the positional cloning of Snn1 , a member of the wall-associated kinase class of receptors, which are known to drive pathways for biotrophic pathogen resistance. Recognition of SnTox1 by Snn1 activates programmed cell death, which allows this necrotroph to gain nutrients and sporulate. These results demonstrate that necrotrophic pathogens such as P. nodorum hijack host molecular pathways that are typically involved in resistance to biotrophic pathogens, revealing the complex nature of susceptibility and resistance in necrotrophic and biotrophic pathogen interactions with plants.

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

PARylation of the forkhead-associated domain protein DAWDLE regulates plant immunity - Feng - 2016 - EMBO reports - Wiley Online Library

PARylation of the forkhead-associated domain protein DAWDLE regulates plant immunity - Feng - 2016 - EMBO reports - Wiley Online Library | microbial pathogenesis and plant immunity | Scoop.it
Protein poly(ADP-ribosyl)ation (PARylation) primarily catalyzed by poly(ADP-ribose) polymerases (PARPs) plays a crucial role in controlling various cellular responses. However, PARylation targets and their functions remain largely elusive. Here, we deployed an Arabidopsis protein microarray coupled with in vitro PARylation assays to globally identify PARylation targets in plants. Consistent with the essential role of PARylation in plant immunity, the forkhead-associated (FHA) domain protein DAWDLE (DDL), one of PARP2 targets, positively regulates plant defense to both adapted and non-adapted pathogens. Arabidopsis PARP2 interacts with and PARylates DDL, which was enhanced upon treatment of bacterial flagellin. Mass spectrometry and mutagenesis analysis identified multiple PARylation sites of DDL by PARP2. Genetic complementation assays indicate that DDL PARylation is required for its function in plant immunity. In contrast, DDL PARylation appears to be dispensable for its previously reported function in plant development partially mediated by the regulation of microRNA biogenesis. Our study uncovers many previously unknown PARylation targets and points to the distinct functions of DDL in plant immunity and development mediated by protein PARylation and small RNA biogenesis, respectively.

Via Suayib Üstün
more...
No comment yet.
Rescooped by Jim Alfano from MycorWeb Plant-Microbe Interactions
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 | microbial pathogenesis and plant immunity | 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
more...
No comment yet.
Rescooped by Jim Alfano from Plants and Microbes
Scoop.it!

New Phytologist: An assay for entry of secreted fungal effectors into plant cells (2016)

New Phytologist: An assay for entry of secreted fungal effectors into plant cells (2016) | microbial pathogenesis and plant immunity | Scoop.it
Successful colonization of plants by prokaryotic and eukaryotic pathogens requires active effector-mediated suppression of defense responses and host tissue reprogramming. Secreted effector proteins can either display their activity in the apoplast or translocate into host cells and function therein. Although characterized in bacteria, the molecular mechanisms of effector delivery by fungal phytopathogens remain elusive.Here we report the establishment of an assay that is based on biotinylation of effectors in the host cytoplasm as hallmark of uptake. The assay exploits the ability of the bacterial biotin ligase BirA to biotinylate any protein that carries a short peptide (Avitag). It is based on the stable expression of BirA in the cytoplasm of maize plants and on engineering of Ustilago maydis strains to secrete Avitagged effectors.We demonstrate translocation of a number of effectors in the U. maydis–maize system and show data that suggest that the uptake mechanism could be rather nonspecificThe assay promises to be a powerful tool for the classification of effectors as well as for the functional study of effector uptake mechanism not only in the chosen system but more generally for systems where biotrophic interactions are established.

 

 


Via Kamoun Lab @ TSL
more...
No comment yet.
Rescooped by Jim Alfano from Plant-Microbe Symbiosis
Scoop.it!

Root Development and Endosymbioses: DELLAs Lead the Orchestra

Root Development and Endosymbioses: DELLAs Lead the Orchestra | microbial pathogenesis and plant immunity | Scoop.it
The plasticity of the root system development is crucial for plant adaptation to changing soil environments. External cues control root growth and differentiation as well as beneficial plant–microorganism symbiotic associations. Arbuscular mycorrhizal (AM) and rhizobial endosymbioses are mutualistic interactions respectively formed between most Angiosperms and Glomeromycota soil fungi under nutrient (e.g., phosphorus) starvation, and between legume (Fabacae) plants and soil bacteria collectively referred to as Rhizobia when soil nitrogen availability is limiting. In both cases, microorganisms colonize host roots depending on related signaling pathways, and in the rhizobial symbiosis, the plant additionally forms nodule organs allowing nitrogen fixation.

DELLA proteins are GRAS transcriptional regulators whose accumulation highly depends on the GA hormonal pool [1. Indeed, GAs promote a targeted degradation of DELLA proteins mediated by the SCF/26S proteasome. As a result of their capacity to interact with multiple transcription factors from diverse families [1, 2], DELLA proteins are emerging as integrators of transcriptional networks associated with various signaling pathways, and notably controlling root growth and endosymbiotic associations.

Via Christophe Jacquet, Francis Martin, Jean-Michel Ané
more...
Tian Zeng's curator insight, September 27, 12:00 PM
della showed central role in development and symbiosis
Rescooped by Jim Alfano from Microbiome and plant immunity
Scoop.it!

Bidirectional cross-kingdom RNAi and fungal uptake of external RNAs confer plant protection

Bidirectional cross-kingdom RNAi and fungal uptake of external RNAs confer plant protection | microbial pathogenesis and plant immunity | Scoop.it
Aggressive fungal pathogens such as Botrytis and Verticillium spp. cause severe crop losses worldwide. We recently discovered that Botrytis cinerea delivers small RNAs (Bc–sRNAs) into plant cells to silence host immunity genes. Such sRNA effectors are mostly produced by Botrytis cinerea Dicer-like protein 1 (Bc-DCL1) and Bc-DCL2. Here we show that expressing sRNAs that target Bc-DCL1 and Bc-DCL2 in Arabidopsis and tomato silences Bc-DCL genes and attenuates fungal pathogenicity and growth, exemplifying bidirectional cross-kingdom RNAi and sRNA trafficking between plants and fungi. This strategy can be adapted to simultaneously control multiple fungal diseases. We also show that Botrytis can take up external sRNAs and double-stranded RNAs (dsRNAs). Applying sRNAs or dsRNAs that target Botrytis DCL1 and DCL2 genes on the surface of fruits, vegetables and flowers significantly inhibits grey mould disease. Such pathogen gene-targeting RNAs represent a new generation of environmentally friendly fungicides.

Via Giannis Stringlis
more...
No comment yet.
Rescooped by Jim Alfano from Interaction, and more...
Scoop.it!

Intracellular innate immune surveillance devices in plants and animals

Intracellular innate immune surveillance devices in plants and animals | microbial pathogenesis and plant immunity | Scoop.it
Multicellular eukaryotes coevolve with microbial pathogens, which exert strong selective pressure on the immune systems of their hosts. Plants and animals use intracellular proteins of the nucleotide-binding domain, leucine-rich repeat (NLR) superfamily to detect many types of microbial pathogens. The NLR domain architecture likely evolved independently and convergently in each kingdom, and the molecular mechanisms of pathogen detection by plant and animal NLRs have long been considered to be distinct. However, microbial recognition mechanisms overlap, and it is now possible to discern important key trans-kingdom principles of NLR-dependent immune function. Here, we attempt to articulate these principles. We propose that the NLR architecture has evolved for pathogen-sensing in diverse organisms because of its utility as a tightly folded “hair trigger” device into which a virtually limitless number of microbial detection platforms can be integrated. Recent findings suggest means to rationally design novel recognition capabilities to counter disease.

Via Ryohei Thomas Nakano
more...
No comment yet.
Rescooped by Jim Alfano from Plants and Microbes
Scoop.it!

eLife: A complete toolset for the study of Ustilago bromivora and Brachypodium sp. as a fungal-temperate grass pathosystem (2016)

eLife: A complete toolset for the study of Ustilago bromivora and Brachypodium sp. as a fungal-temperate grass pathosystem (2016) | microbial pathogenesis and plant immunity | Scoop.it

Due to their economic relevance, the study of plant pathogen interactions is of importance. However, elucidating these interactions and their underlying molecular mechanisms remains challenging since both host and pathogen need to be fully genetically accessible organisms. Here we present milestones in the establishment of a new biotrophic model pathosystem: Ustilago bromivora and Brachypodium sp. We provide a complete toolset, including an annotated fungal genome and methods for genetic manipulation of the fungus and its host plant. This toolset will enable researchers to easily study biotrophic interactions at the molecular level on both the pathogen and the host side. Moreover, our research on the fungal life cycle revealed a mating type bias phenomenon. U. bromivora harbors a haplo-lethal allele that is linked to one mating type region. As a result, the identified mating type bias strongly promotes inbreeding, which we consider to be a potential speciation driver.


Via Ronny Kellner, Kamoun Lab @ TSL
more...
No comment yet.
Rescooped by Jim Alfano from Host-Microbe Interactions. Plant Biology.
Scoop.it!

The pattern-recognition receptor CORE of Solanaceae detects bacterial cold-shock protein


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

Science: Regulation of sugar transporter activity for antibacterial defense in Arabidopsis (2016)

Science: Regulation of sugar transporter activity for antibacterial defense in Arabidopsis (2016) | microbial pathogenesis and plant immunity | Scoop.it

Microbial pathogens strategically acquire metabolites from their hosts during infection. Here we show that the host can intervene to prevent such metabolite loss to pathogens. Phosphorylation-dependent regulation of sugar transporter 13 (STP13) is required for antibacterial defense in the plant Arabidopsis thaliana. STP13 physically associates with the flagellin receptor flagellin-sensitive 2 (FLS2) and its co-receptor BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1 (BAK1). BAK1 phosphorylates STP13 at threonine 485, which enhances its monosaccharide uptake activity to compete with bacteria for extracellular sugars. Limiting the availability of extracellular sugar deprives bacteria of an energy source and restricts virulence factor delivery. Our results reveal that control of sugar uptake, managed by regulation of a host sugar transporter, is a defense strategy deployed against microbial infection. Competition for sugar thus shapes host-pathogen interactions.


Via Kamoun Lab @ TSL, Suayib Üstün
more...
No comment yet.
Rescooped by Jim Alfano from Plants and Microbes
Scoop.it!

New Phytologist: Convergent evolution of filamentous microbes towards evasion of glycan-triggered immunity (2016)

New Phytologist: Convergent evolution of filamentous microbes towards evasion of glycan-triggered immunity (2016) | microbial pathogenesis and plant immunity | Scoop.it

All filamentous microbes produce and release a wide range of glycans, which are essential determinants of microbe–microbe and microbe–host interactions. Major cell wall constituents, such as chitin and β-glucans, are elicitors of host immune responses. The widespread capacity for glycan perception in plants has driven the evolution of various strategies that help filamentous microbes to evade detection. Common strategies include structural and chemical modifications of cell wall components as well as the secretion of effector proteins that suppress chitin- and β-glucan-triggered immune responses. Thus, the necessity to avoid glycan-triggered immunity represents a driving force in the convergent evolution of filamentous microbes towards its suppression.


Via Kamoun Lab @ TSL
more...
Rescooped by Jim Alfano from Plant immunity and legume symbiosis
Scoop.it!

CML8, an Arabidopsis calmodulin-like protein plays a role in Pseudomonas syringae plant immunity

CML8, an Arabidopsis calmodulin-like protein plays a role in Pseudomonas syringae plant immunity | microbial pathogenesis and plant immunity | Scoop.it
Calcium is a universal second messenger involved in various cellular processes including plant development and stress responses. Its conversion into biological responses requires the presence of calcium sensor relays such as calmodulin (CaM) and calmodulin-like proteins (CMLs). While the role of CaM is well described, CML functions remain largely uncharacterized. Here, we show that the Arabidopsis CML8 expression is strongly and transiently induced by Pseudomonas syringae and reverse genetic approaches indicated that the over-expression of CML8 confers on plants a better resistance to pathogenic bacteria compared to wild type, knock-down and knock-out lines indicating that CML8 participates as a positive regulator in plant immunity. However, this difference disappeared when inoculations were performed using bacteria unable to inject effectors into a plant host cell or deficient for some effectors known to target the salicylic acid (SA) signaling pathway. SA content and PR1 protein accumulation were altered in CML8 transgenic lines supporting a role for CML8 in SA-dependent processes. Pathogen Associated Molecular Patterns (PAMPs) treatments with flagellin and elf18 peptides have no effects on CML8 gene expression and do not modify root growth of CML8 knock-down and over-expressing lines compared to WT plants. Collectively, our results support a role for CML8 in plant immunity against P. syringae.

Via Christophe Jacquet
more...
No comment yet.
Rescooped by Jim Alfano from Microbiome and plant immunity
Scoop.it!

Pseudomonas syringae Differentiates into Phenotypically Distinct Subpopulations During Colonization of a Plant Host

Pseudomonas syringae Differentiates into Phenotypically Distinct Subpopulations During Colonization of a Plant Host | microbial pathogenesis and plant immunity | Scoop.it
Authors: José S. Rufián, María-Antonia Sánchez-Romero, Diego López-Márquez, Alberto P. Macho, John W. Mansfield, Dawn L. Arnold, Javier Ruiz-Albert, Josep Casadesús and Carmen R. Beuzón.
Journal: Environmental Microbiology

Summary: 
Bacterial microcolonies with heterogeneous sizes are formed during colonization of Phaseolus vulgaris by Pseudomonas syringae. Heterogeneous expression of structural and regulatory components of the P. syringae type III secretion system (T3SS), essential for colonization of the host apoplast and disease development, is likewise detected within the plant apoplast. T3SS expression is bistable in the homogeneous environment of nutrient-limited T3SS-inducing medium, suggesting that subpopulation formation is not a response to different environmental cues. T3SS bistability is reversible, indicating a non-genetic origin, and the T3SSHIGH and T3SSLOW subpopulations show differences in virulence. T3SS bistability requires the transcriptional activator HrpL, the double negative regulatory loop established by HrpV and HrpG, and may be enhanced through a positive feedback loop involving HrpA, the main component of the T3SS pilus. To our knowledge, this is the first example of phenotypic heterogeneity in the expression of virulence determinants during colonization of a non-mammalian host. 

Via Freddy Monteiro, Giannis Stringlis
more...
Freddy Monteiro's curator insight, November 3, 4:53 PM
Take note of this phenomenon. Findings described here will be validated in other plant pathogens.
Rescooped by Jim Alfano from Plant pathogens and pests
Scoop.it!

The Non-Flagellar Type III Secretion System Evolved from the Bacterial Flagellum and Diversified into Host-Cell Adapted Systems

The Non-Flagellar Type III Secretion System Evolved from the Bacterial Flagellum and Diversified into Host-Cell Adapted Systems | microbial pathogenesis and plant immunity | Scoop.it
Most motile bacteria use a flagellum to move. The extracellular components of flagella are secreted by their own Type 3 Secretion System (T3SS). The non-flagellar T3SS (NF-T3SS), also named injectisome, includes many proteins that are homologous to flagellar components. NF-T3SSs are employed by many plant and animal pathogens to deliver effectors to host cells, including toxins. NF-T3SSs are complex protein machineries with >15 components that connect bacterial cell envelopes to eukaryotic cell membranes, including the intervening extracellular space. In this study, we designed computational tools to distinguish flagella and NF-T3SSs from other bacterial protein sequences. We show that NF-T3SSs evolved from the flagellum by a series of genetic deletions, innovations, and recruitments of components from other cellular structures. Our evolutionary analysis suggests that NF-T3SSs then quickly adapted to different eukaryotic cells while maintaining a core structure that remains highly similar to the flagellum. This is an example of evolutionary tinkering where a complex structure arises by exaptation, the recruitment of elements that evolved initially for other functions in other cellular structures.

Via Christophe Jacquet
more...
No comment yet.
Rescooped by Jim Alfano from Plants and Microbes
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) | microbial pathogenesis and plant immunity | 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
more...
No comment yet.
Rescooped by Jim Alfano from Plant-microbe interaction
Scoop.it!

Activation-Dependent Destruction of a Co-receptor by a Pseudomonas syringae Effector Dampens Plant Immunity

Activation-Dependent Destruction of a Co-receptor by a Pseudomonas syringae Effector Dampens Plant Immunity | microbial pathogenesis and plant immunity | Scoop.it
The Arabidopsis immune receptor FLS2 and co-receptor BAK1 perceive the bacterial flagellin epitope flg22 to activate plant immunity. To prevent this response, phytopathogenic bacteria deploy a repertoire of effector proteins to perturb immune signaling. However, the effector-induced perturbation is often sensed by the host, triggering another layer of immunity. We report that the Pseudomonas syringae effector HopB1 acts as a protease to cleave immune-activated BAK1. Prior to activation, HopB1 constitutively interacts with FLS2. Upon activation by flg22, BAK1 is recruited to the FLS2-HopB1 complex and is phosphorylated at Thr455. HopB1 then specifically cleaves BAK1 between Arg297 and Gly298 to inhibit FLS2 signaling. Although perturbation of BAK1 is known to trigger increased immune responses in plants, the HopB1-mediated cleavage of BAK1 leads to enhanced virulence, but not disease resistance. This study thus reveals a virulence strategy by which a pathogen effector attacks the plant immune system with minimal host perturbation.

Via Suayib Üstün
Jim Alfano's insight:
Share your insight
more...
MONAGHAN LAB's curator insight, October 26, 4:47 PM
JML Journal Club 2016.11.02
Rescooped by Jim Alfano from Plant pathogens and pests
Scoop.it!

Magnaporthe oryzae Glycine-Rich Secretion Protein, Rbf1 Critically Participates in Pathogenicity through the Focal Formation of the Biotrophic Interfacial Complex

Magnaporthe oryzae  Glycine-Rich Secretion Protein, Rbf1 Critically Participates in Pathogenicity through the Focal Formation of the Biotrophic Interfacial Complex | microbial pathogenesis and plant immunity | Scoop.it
Author Summary Biotrophic pathogens grow inside living host cells by secreting “effector” proteins that suppress host innate immunity. Magnaporthe oryzae , which causes the most serious damage to rice, and recently also to wheat, is a hemibiotrophic fungus. During the biotrophic invasion, a host membrane-rich structure called the biotrophic interfacial complex (BIC) is focally formed at the periphery of the invasive hyphae. Several effectors have been reported to accumulate in the BIC; however, its role is unknown. In this study, we identified a novel M . oryzae -specific virulence effector gene, R equired-for-Focal- B IC- F ormation 1 ( RBF1 ). When RBF1 was absent, the fungus was incapable of forming the focal BIC structure. RBF1 expression was transiently increased each time the fungus penetrated a neighboring rice cell, which is consistent with the BIC formation in each invaded cell. The RBF1 -disrupted mutants triggered higher immune responses and showed drastically reduced pathogenicity; however, it was able to cause disease in immuno-depressed rice plants. These results indicate that the focal BIC formation is critical for suppressing host immune responses and to the virulence of M . oryzae . The mode of action of the focal BIC is unknown, but the acquisition of RBF1 might enable M . oryzae to combat effectively against host innate immunity.

Via Yogesh Gupta, Christophe Jacquet
more...
No comment yet.
Rescooped by Jim Alfano from Host-Microbe Interactions. Plant Biology.
Scoop.it!

The Plant Microbiota: Systems-Level Insights and Perspectives - Annual Review of Genetics, 50(1):

The Plant Microbiota: Systems-Level Insights and Perspectives - Annual Review of Genetics, 50(1): | microbial pathogenesis and plant immunity | Scoop.it

Via Tatsuya Nobori
more...
No comment yet.