Effectors and Pla...
Follow
Find
39.5K views | +8 today
 
Rescooped by Nicolas Denancé from Plants and Microbes
onto Effectors and Plant Immunity
Scoop.it!

OpenAshDieBack: A hub for crowdsourcing information and genomic resources for Ash Dieback

OpenAshDieBack: A hub for crowdsourcing information and genomic resources for Ash Dieback | Effectors and Plant Immunity | Scoop.it
Welcome to Open Access Data and Crowdsourced analyses!

On this website you'll be able to get data to do your own analyses on ash and ash dieback. You can see the results of other peoples work as soon as it is available and share your own discoveries in the same way.

You will always get full credit for your work and in doing so contribute to a real community effort.

Via Kamoun Lab @ TSL
more...
No comment yet.
Effectors and Plant Immunity
Strategies of plant defense and microbe attacks
Your new post is loading...
Your new post is loading...
Scooped by Nicolas Denancé
Scoop.it!

Front. Plant Sci./Front. Microbiol.: Genomics and Effectomics of the crop killer Xanthomonas

Front. Plant Sci./Front. Microbiol.: Genomics and Effectomics of the crop killer Xanthomonas | Effectors and Plant Immunity | Scoop.it

Published articles:

 

10. Mini-review by Zhang et al.: TAL effectors and the executor R genes. Front. Plant Sci. (2015)

 

9. Research article by ÜStun et al.: The Xanthomonas effector XopJ triggers a conditional hypersensitive response upon treatment of N. benthamiana leaves with salicylic acid. Front. Plant Sci. (2015)

 

8. Methods by Pérez-Quintero et al.:  QueTAL: a suite of tools to classify and compare TAL effectors functionally and phylogenetically. Front. Plant Sci. (2015)

 

7. Hypothesis and theory by Wilkins et al.: TAL effectors and activation of predicted host targets distinguish Asian from African strains of the rice pathogen Xanthomonas oryzae pv. oryzicola while strict conservation suggests universal importance of five TAL effectors. Front. Plant Sci. (2015)

 

6. Review by Hutin et al.: MorTAL Kombat: the story of defense against TAL effectors through loss-of-susceptibility. Front. Plant Sci. (2015)

 

5. Research article by Jacobs et al.: Comparative genomics of a cannabis pathogen reveals insight into the evolution of pathogenicity in Xanthomonas. Front. Plant Sci. (2015)

 

4. Research article by Schwartz et al.: Phylogenomics of Xanthomonas field strains infecting pepper and tomato reveals diversity in effector repertoires and identifies determinants of host specificity. Front. Microbiol. (2015)

 

3. Perspective by Dossa et al.: Decision tools for bacterial blight resistance gene deployment in rice-based agricultural ecosystems. Front. Plant Sci. (2015)

 

2. Mini-review by Pieretti et al.: What makes Xanthomonas albilineans unique amongst xanthomonads? Front. Plant Sci. (2015)

 

1. Mini-review by S. Üstün and F. Börnke: Interactions of Xanthomonas type-III effector proteins with the plant ubiquitin and ubiquitin-like pathways. Front. Plant Sci. (2014)

more...
Suayib Üstün's curator insight, July 29, 2014 2:57 PM

Great topic-excited!

Rescooped by Nicolas Denancé from Plants and Microbes
Scoop.it!

Storify: Tweets from #evolpathkiel Evolutionary genomics of plant pathogens, Kiel, August 2015


Via Kamoun Lab @ TSL
more...
No comment yet.
Rescooped by Nicolas Denancé from Plant pathogens and pests
Scoop.it!

Key steps in type III secretion system (T3SS) towards translocon assembly with potential sensor at plant plasma membrane - Molecular Plant Pathology

Key steps in type III secretion system (T3SS) towards translocon assembly with potential sensor at plant plasma membrane - Molecular Plant Pathology | Effectors and Plant Immunity | Scoop.it
Many plant- and animal-pathogenic Gram-negative bacteria employ the type III secretion system (T3SS) to translocate effector proteins from bacterial cells into the cytosol of eukaryotic host cells. The effector translocation occurs through an integral component of T3SS, the channel-like translocon, assembled by hydrophilic and hydrophobic proteinaceous translocators in a two-step process. In the first, hydrophilic translocators localize to the tip of a proteinaceous needle in animal pathogens, or a proteinaceous pilus in plant pathogens, and associate with hydrophobic translocators, which insert into host plasma membranes in the second step. However, the pilus needs to penetrate plant cell walls in advance. All hydrophilic translocators so far identified in plant pathogens are characteristic of harpins: T3SS accessory proteins containing a unitary hydrophilic domain or an additional enzymatic domain. Two-domain harpins carrying a pectate lyase domain potentially target plant cell walls and facilitate the penetration of the pectin-rich middle lamella by the bacterial pilus. One-domain harpins target plant plasma membranes and may play a crucial role in translocon assembly, which may also involve contrapuntal associations of hydrophobic translocators. In all cases, sensory components in the target plasma membrane are indispensable for the membrane recognition of translocators and the functionality of the translocon. The conjectural sensors point to membrane lipids and proteins, and a phosphatidic acid and an aquaporin are able to interact with selected harpin-type translocators. Interactions between translocators and their sensors at the target plasma membrane are assumed to be critical for translocon assembly.

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

Xylella Fastidiosa : Avis d'information aux voyageurs (2015)

Xylella Fastidiosa : Avis d'information aux voyageurs (2015) | Effectors and Plant Immunity | Scoop.it

La Préfecture de Haute-Corse informe les voyageurs de l'interdiction d'introduction des végétaux dans le cadre de la lutte contre la Xylella Fastidiosa.

 

The prefecture of Haute-Corse inform passengers of the prohibition of introduction of plants as part of the fight against Xylella fastidiosa.


Via Kamoun Lab @ TSL
more...
No comment yet.
Scooped by Nicolas Denancé
Scoop.it!

Front. Plant Sci.: TAL effectors and the executor R genes (2015)

Front. Plant Sci.: TAL effectors and the executor R genes (2015) | Effectors and Plant Immunity | Scoop.it

Transcription activation-like (TAL) effectors are bacterial type III secretion proteins that function as transcription factors in plants during Xanthomonas/plant interactions, conditioning either host susceptibility and/or host resistance. Three types of TAL effector associated resistance (R) genes have been characterized - recessive, dominant non-transcriptional and dominant TAL effector-dependent transcriptional based resistance. Here, we discuss the last type of R genes, whose functions are dependent on direct TAL effector binding to discrete effector binding elements in the promoters. Only five of the so-called executor R genes have been cloned, and commonalities are not clear. We have placed the protein products in two groups for conceptual purposes. Group 1 consists solely of the protein from pepper, BS3, which is predicted to have catalytic function on the basis of homology to a large conserved protein family. Group 2 consists of BS4C-R, XA27, XA10, and XA23, all of which are relatively short proteins from pepper or rice with multiple potential transmembrane domains. Group 2 members have low sequence similarity to proteins of unknown function in closely related species. Firm predictions await further experimentation on these interesting new members to the R gene repertoire, which have potential broad application in new strategies for disease resistance.

 

Zhang J, Yin Z and White F

 

 

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

Front. Plant Sci.: The Xanthomonas effector XopJ triggers a conditional hypersensitive response upon treatment of N. benthamiana leaves with salicylic acid (2015)

Front. Plant Sci.: The Xanthomonas effector XopJ triggers a conditional hypersensitive response upon treatment of N. benthamiana leaves with salicylic acid (2015) | Effectors and Plant Immunity | Scoop.it

XopJ is a Xanthomonas type III effector protein that promotes bacterial virulence on susceptible pepper plants through the inhibition of the host cell proteasome and a resultant suppression of salicylic acid (SA) – dependent defense responses. We show here that Nicotiana benthamiana leaves transiently expressing XopJ display hypersensitive response (HR) –like symptoms when exogenously treated with SA. This apparent avirulence function of XopJ was further dependent on effector myristoylation as well as on an intact catalytic triad, suggesting a requirement of its enzymatic activity for HR-like symptom elicitation. The ability of XopJ to cause a HR-like symptom development upon SA treatment was lost upon silencing of SGT1 and NDR1, respectively, but was independent of EDS1 silencing, suggesting that XopJ is recognized by an R protein of the CC-NBS-LRR class. Furthermore, silencing of NPR1 abolished the elicitation of HR-like symptoms in XopJ expressing leaves after SA application. Measurement of the proteasome activity indicated that proteasome inhibition by XopJ was alleviated in the presence of SA, an effect that was not observed in NPR1 silenced plants. Our results suggest that XopJ - triggered HR-like symptoms are closely related to the virulence function of the effector and that XopJ follows a two-signal model in order to elicit a response in the non-host plant N. benthamiana.

 

Üstün S, Bartetzko V and Börnke F

 

 

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

Science: Salicylic acid modulates colonization of the root microbiome by specific bacterial taxa (2015)

Immune systems distinguish “self” from “non-self” to maintain homeostasis and must differentially gate access to allow colonization by potentially beneficial, non-pathogenic microbes. Plant roots grow within extremely diverse soil microbial communities, but assemble a taxonomically limited root-associated microbiome. We grew isogenic Arabidopsis thaliana mutants with altered immune systems in a wild soil and also in recolonization experiments with a synthetic bacterial community. We established that biosynthesis of, and signaling dependent on, the foliar defense phytohormone salicylic acid is required to assemble a normal root microbiome. Salicylic acid modulates colonization of the root by specific bacterial families. Thus, plant immune signaling drives selection from the available microbial communities to sculpt the root microbiome.

 

Sarah L. Lebeis, Sur Herrera Paredes, Derek S. Lundberg, Natalie Breakfield, Jase Gehring, Meredith McDonald, Stephanie Malfatti, Tijana Glavina del Rio, Corbin D. Jones, Susannah G. Tringe, Jeffery L. Dangl

more...
No comment yet.
Rescooped by Nicolas Denancé from Plant Immunity And Microbial Effectors
Scoop.it!

The Plasmodiophora brassicae genome reveals insights in its life cycle and ancestry of chitin synthases : Scientific Reports : Nature Publishing Group

The Plasmodiophora brassicae genome reveals insights in its life cycle and ancestry of chitin synthases : Scientific Reports : Nature Publishing Group | Effectors and Plant Immunity | Scoop.it

Via IPM Lab
more...
No comment yet.
Rescooped by Nicolas Denancé from Plant-Microbe Symbioses
Scoop.it!

The ‘prime-ome’: towards a holistic approach to priming

The ‘prime-ome’: towards a holistic approach to priming | Effectors and Plant Immunity | Scoop.it
Plants can be primed to respond faster and more strongly to stress and multiple pathways, specific for the encountered challenge, are involved in priming. This adaptability of priming makes it difficult to pinpoint an exact mechanism: the same phenotypic observation might be the consequence of unrelated underlying events. Recently, details of the molecular aspects of establishing a primed state and its transfer to offspring have come to light. Advances in techniques for detection and quantification of elements spanning the fields of transcriptomics, proteomics, and metabolomics, together with adequate bioinformatics tools, will soon allow us to take a holistic approach to plant defence. This review highlights the state of the art of new strategies to study defence priming in plants and provides perspectives towards ‘prime-omics’.

Via Jean-Michel Ané
more...
No comment yet.
Rescooped by Nicolas Denancé from Plants and Microbes
Scoop.it!

Slides: Plant pathology in the post-genomics era (2015)

Presented at BASF Science Symposium: sustainable food chain - from field to table, Jun 23-24, 2015, Chicago.

 

Notes and acknowledgements at http://kamounlab.tumblr.com/post/122151022390/plant-pathology-in-the-post-genomics-era


Via Kamoun Lab @ TSL
more...
No comment yet.
Scooped by Nicolas Denancé
Scoop.it!

Front. Plant Sci.: QueTAL: a suite of tools to classify and compare TAL effectors functionally and phylogenetically (2015)

Front. Plant Sci.: QueTAL: a suite of tools to classify and compare TAL effectors functionally and phylogenetically (2015) | Effectors and Plant Immunity | Scoop.it
Transcription Activator-Like (TAL) effectors from Xanthomonas plant pathogenic bacteria can bind to the promoter region of plant genes and induce their expression. DNA-binding specificity is governed by a central domain made of nearly identical repeats, each determining the recognition of one base pair via two amino acid residues (a.k.a. Repeat Variable Di-residue, or RVD). Knowing how TAL effectors differ from each other within and between strains would be useful to infer functional and evolutionary relations, but their repetitive nature precludes reliable use of traditional alignment methods. The suite QueTAL was therefore developed to offer tailored tools for comparison of TAL effector genes. The program DisTAL considers each repeat as a unit, transforms a TAL effector sequence into a sequence of coded repeats and makes pair-wise alignments between these coded sequences to construct trees. The program FuncTAL is aimed at finding TAL effectors with similar DNA-binding capabilities. It calculates correlations between position weight matrices obtained from the RVD sequence, and builds trees based on these correlations. The programs accurately represented phylogenetic and functional relations between TAL effectors using either simulated or literature-curated data. When using the programs on a large set of TAL effector sequences, the DisTAL tree largely reflected the expected species phylogeny. In contrast, FuncTAL showed that TAL effectors with similar binding capabilities can be found between phylogenetically distant taxa. This suite will help users to rapidly analyse any TAL effector genes of interest and compare them to other available TAL genes and should improve our understanding of TAL effectors evolution. It is available at http://bioinfo-web.mpl.ird.fr/cgi-bin2/quetal/quetal.cgi.
more...
No comment yet.
Scooped by Nicolas Denancé
Scoop.it!

Front. Plant Sci.: MorTAL Kombat: the story of defense against TAL effectors through loss-of-susceptibility (2015)

Front. Plant Sci.: MorTAL Kombat: the story of defense against TAL effectors through loss-of-susceptibility (2015) | Effectors and Plant Immunity | Scoop.it

Many plant-pathogenic xanthomonads rely on Transcription Activator-Like (TAL) effectors to colonize their host. This particular family of type III effectors functions as specific plant transcription factors via a novel programmable DNA-binding domain. Upon binding to the promoters of plant disease susceptibility genes in a sequence-specific manner, the expression of these host genes is induced. However, plants have evolved specific strategies to counter the action of TAL effectors and confer resistance. One mechanism is to avoid the binding of TAL effectors by mutations of their DNA binding sites, resulting in resistance by loss-of-susceptibility. This article reviews our current knowledge of the susceptibility hubs targeted by Xanthomonas TAL effectors, possible evolutionary scenarios for plants to combat the pathogen with loss-of-function alleles, and how this knowledge can be used overall to develop new pathogen-informed breeding strategies and improve crop resistance.

 

Hutin M, Pérez-Quintero AL, Lopez C and Szurek B

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

Cell Host Microb.: Pseudomonas syringae pv. tomato DC3000 Type III Secretion Effector Polymutants Reveal an Interplay between HopAD1 and AvrPtoB (2015)

Cell Host Microb.: Pseudomonas syringae pv. tomato DC3000 Type III Secretion Effector Polymutants Reveal an Interplay between HopAD1 and AvrPtoB (2015) | Effectors and Plant Immunity | Scoop.it

The bacterial pathogen Pseudomonas syringae pv. tomato DC3000 suppresses the two-tiered plant innate immune system by injecting a complex repertoire of type III secretion effector (T3E) proteins. Beyond redundancy and interplay, individual T3Es may interact with multiple immunity-associated proteins, rendering their analysis challenging. We constructed a Pst DC3000 polymutant lacking all 36 T3Es and restored individual T3Es or their mutants to explore the interplay among T3Es. The weakly expressed T3E HopAD1 was sufficient to elicit immunity-associated cell death in Nicotiana benthamiana. HopAD1-induced cell death was suppressed partially by native AvrPtoB and completely by AvrPtoBM3, which has mutations disrupting its E3 ubiquitin ligase domain and two known domains for interacting with immunity-associated kinases. AvrPtoBM3 also gained the ability to interact with the immunity-kinase MKK2, which is required for HopAD1-dependent cell death. Thus, AvrPtoB has alternative, competing mechanisms for suppressing effector-triggered plant immunity. This approach allows the deconvolution of individual T3E activities.

 

Hai-Lei Wei, Suma Chakravarthy, Johannes Mathieu, Tyler C. Helmann, Paul Stodghill, Bryan Swingle, Gregory B. Martin, Alan Collmer

more...
No comment yet.
Rescooped by Nicolas Denancé from Plant & Evolution
Scoop.it!

An introduction to synthetic biology in plant systems


Via Pierre-Marc Delaux
more...
No comment yet.
Rescooped by Nicolas Denancé from Plants and Microbes
Scoop.it!

New Disease Reports: A bacterial leaf spot of aquilegia caused by Pseudomonas syringae (2014)

New Disease Reports: A bacterial leaf spot of aquilegia caused by Pseudomonas syringae (2014) | Effectors and Plant Immunity | Scoop.it

Aquilegia vulgaris (Ranunculaceae) (Columbine) is a flowering herbaceous perennial native to Europe and widely cultivated in UK gardens. It is an important crop for some commercial nurseries that produce large numbers of potted plants for retail sale in garden centres. In 2008, 100% crop loss due to a bacterial disease was reported by one grower. Subsequently, during a survey of bacterial diseases of herbaceous perennials on commercial nurseries carried out during 2010 (Roberts, 2011), symptoms consisting of black spots or larger lesions with a water-soaked margin were observed on the leaves and stems of plants at two nurseries in different regions of the UK.


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

Subversion of plant cellular functions by bacterial type-III effectors: beyond suppression of immunity - New Phytologist

Subversion of plant cellular functions by bacterial type-III effectors: beyond suppression of immunity - New Phytologist | Effectors and Plant Immunity | Scoop.it

Most bacterial plant pathogens employ a type-III secretion system to inject type-III effector (T3E) proteins directly inside plant cells. These T3Es manipulate host cellular processes in order to create a permissive niche for bacterial proliferation, allowing development of the disease. An important role of T3Es in plant pathogenic bacteria is the suppression of plant immune responses. However, in recent years, research has uncovered T3E functions different from direct immune suppression, including the modulation of plant hormone signaling, metabolism or organelle function. This insight article discusses T3E functions other than suppression of immunity, which may contribute to the modulation of plant cells in order to promote bacterial survival, nutrient release, and bacterial replication and dissemination.


Via Max-Bernhard Ballhausen, Suayib Üstün, Jim Alfano
more...
No comment yet.
Scooped by Nicolas Denancé
Scoop.it!

Why are so few insect species vectors/candidate vectors of Xylella fastidiosa in Salento, Italy?

Why are so few insect species vectors/candidate vectors of Xylella fastidiosa in Salento, Italy? | Effectors and Plant Immunity | Scoop.it
The discovery of Xylella fastidiosa (Xf) in the Salento area of Southern Italy, associated with a severe syndrome of olive trees, named CoDiRO, complesso del disseccamento rapido, or OQDS, olive qu...
more...
No comment yet.
Rescooped by Nicolas Denancé from Plants and Microbes
Scoop.it!

Olive Oil Times: European Commission Publishes Xylella Fastidiosa Factsheet (2015)

Olive Oil Times: European Commission Publishes Xylella Fastidiosa Factsheet (2015) | Effectors and Plant Immunity | Scoop.it

The European Commission recently published a question-and-answer factsheet on the bacterium Xylella fastidiosa on its Food Safety website.


The Xylella fastidiosa bacterium has been responsible for the destruction of olive groves in Italy’s Apulia region resulting in the adoption of urgent European Union (EU) measures to try to combat and contain the outbreak and prevent its spread to other member states of the EU.


The introduction to the factsheet points out that Xylella fastidiosa is one of the world’s deadliest plant bacteria which can have an enormous economic impact, and confirms that the outbreak affecting olive groves in Apulia is the only confirmed outbreak in the EU.


It explains that there are four different subspecies of Xylella fastidiosa and that the strain identified in Apulia is a new genetic variant which has so far only attacked olive and plum trees. The bacterium is spread by spittlebugs, cicadas and sharpshooters which feed on the infected plant tissue.


A study by the EU’s Food Safety Authority had warned that the risk of the deadly bacterium spreading to regions in other EU countries was very high. In the face of uncertainty and misinformation about the bacterium and in an effort to educate the general public, the European Commission has released the factsheet which answers six questions:


What measures have been taken by the Commission to prevent further spread into the Union territory?
How will the Commission prevent the further introduction of Xylella fastidiosa from non-EU countries?
Is there any financial support available for farmers affected by Xylella fastidiosa
Could there be other causes for the decline of olive trees since some scientific papers argue that it is caused by a combination of fungi which weaken the plants before being attacked by Xylella fastidiosa, and specific treatments seem to exist?
How can Xylella fastidiosa be controlled?
What can I do as citizen to prevent further spread of Xylella fastidiosa in the EU?


Via Kamoun Lab @ TSL
more...
No comment yet.
Rescooped by Nicolas Denancé from Publications from The Sainsbury Laboratory
Scoop.it!

New Phytologist: Standards for plant synthetic biology: a common syntax for exchange of DNA parts (2015)

New Phytologist: Standards for plant synthetic biology: a common syntax for exchange of DNA parts (2015) | Effectors and Plant Immunity | Scoop.it

Inventors in the field of mechanical and electronic engineering can access multitudes of components and, thanks to standardization, parts from different manufacturers can be used in combination with each other. The introduction of BioBrick standards for the assembly of characterized DNA sequences was a landmark in microbial engineering, shaping the field of synthetic biology. Here, we describe a standard for Type IIS restriction endonuclease-mediated assembly, defining a common syntax of 12 fusion sites to enable the facile assembly of eukaryotic transcriptional units. This standard has been developed and agreed by representatives and leaders of the international plant science and synthetic biology communities, including inventors, developers and adopters of Type IIS cloning methods. Our vision is of an extensive catalogue of standardized, characterized DNA parts that will accelerate plant bioengineering.

 

Nicola J. Patron, Diego Orzaez, Sylvestre Marillonnet, Heribert Warzecha, Colette Matthewman, Mark Youles, Oleg Raitskin, Aymeric Leveau, Gemma Farré, Christian Rogers, Alison Smith, Julian Hibberd, Alex A. R. Webb, James Locke, Sebastian Schornack, Jim Ajioka, David C. Baulcombe, Cyril Zipfel, Sophien Kamoun, Jonathan D. G. Jones, Hannah Kuhn, Silke Robatzek, H. Peter Van Esse, Dale Sanders, Giles Oldroyd, Cathie Martin, Rob Field, Sarah O'Connor, Samantha Fox, Brande Wulff, Ben Miller, Andy Breakspear, Guru Radhakrishnan, Pierre-Marc Delaux, Dominique Loqué, Antonio Granell, Alain Tissier, Patrick Shih, Thomas P. Brutnell, W. Paul Quick, Heiko Rischer, Paul D. Fraser, Asaph Aharoni, Christine Raines, Paul F. South, Jean-Michel Ané, Björn R. Hamberger, Jane Langdale, Jens Stougaard, Harro Bouwmeester, Michael Udvardi, James A. H. Murray, Vardis Ntoukakis, Patrick Schäfer, Katherine Denby, Keith J. Edwards, Anne Osbourn, and Jim Haseloff


Via The Sainsbury Lab
more...
The Sainsbury Lab's curator insight, July 14, 12:25 PM

Inventors in the field of mechanical and electronic engineering can access multitudes of components and, thanks to standardization, parts from different manufacturers can be used in combination with each other. The introduction of BioBrick standards for the assembly of characterized DNA sequences was a landmark in microbial engineering, shaping the field of synthetic biology. Here, we describe a standard for Type IIS restriction endonuclease-mediated assembly, defining a common syntax of 12 fusion sites to enable the facile assembly of eukaryotic transcriptional units. This standard has been developed and agreed by representatives and leaders of the international plant science and synthetic biology communities, including inventors, developers and adopters of Type IIS cloning methods. Our vision is of an extensive catalogue of standardized, characterized DNA parts that will accelerate plant bioengineering.

Rescooped by Nicolas Denancé from Plant-microbe interaction
Scoop.it!

Two serine residues in Pseudomonas syringae effector HopZ1a are required for acetyltransferase activity and association with the host co-factor - Ma - 2015 - New Phytologist - Wiley Online Library

Two serine residues in Pseudomonas syringae effector HopZ1a are required for acetyltransferase activity and association with the host co-factor - Ma - 2015 - New Phytologist - Wiley Online Library | Effectors and Plant Immunity | Scoop.it
Summary
Gram-negative bacteria inject type III secreted effectors (T3SEs) into host cells to manipulate the immune response. The YopJ family effector HopZ1a produced by the plant pathogen Pseudomonas syringae possesses acetyltransferase activity and acetylates plant proteins to facilitate infection.
Using mass spectrometry, we identified a threonine residue, T346, as the main autoacetylation site of HopZ1a. Two neighboring serine residues, S349 and S351, are required for the acetyltransferase activity of HopZ1a in vitro and are indispensable for the virulence function of HopZ1a in Arabidopsis thaliana.
Using proton nuclear magnetic resonance (NMR), we observed a conformational change of HopZ1a in the presence of inositol hexakisphosphate (IP6), which acts as a eukaryotic co-factor and significantly enhances the acetyltransferase activity of several YopJ family effectors. S349 and S351 are required for IP6-binding-mediated conformational change of HopZ1a.
S349 and S351 are located in a conserved region in the C-terminal domain of YopJ family effectors. Mutations of the corresponding serine(s) in two other effectors, HopZ3 of P. syringae and PopP2 of Ralstonia solanacerum, also abolished their acetyltransferase activity. These results suggest that, in addition to the highly conserved catalytic residues, YopJ family effectors also require conserved serine(s) in the C-terminal domain for their enzymatic activity.

Via Suayib Üstün
more...
No comment yet.
Rescooped by Nicolas Denancé from microbial pathogenesis and plant immunity
Scoop.it!

MPP: Identification of novel Xanthomonas euvesicatoria type III effector proteins by a machine-learning approach (2015)

MPP: Identification of novel Xanthomonas euvesicatoria type III effector proteins by a machine-learning approach (2015) | Effectors and Plant Immunity | Scoop.it
The Gram-negative bacterium Xanthomonas euvesicatoria (Xcv) is the causal agent of bacterial spot disease in pepper and tomato. Xcv pathogenicity depends on a type III secretion (T3S) system that delivers effector proteins into host cells to suppress plant immunity and promote disease. The pool of known Xcv effectors includes approximately 30 proteins, most of them identified in the 85-10 strain by various experimental and computational techniques. To identify additional Xcv 85-10 effectors, we applied a genome-wide machine learning approach, in which all ORFs were scored according to their propensity to encode effectors. Scoring was based on a large set of features including genomic organization, taxonomical dispersion, hrp-dependent expression, 5’ regulatory sequences, amino acid composition bias, and GC content. Thirty-six predicted effectors were tested for translocation into plant cells by using the HR-inducing domain of AvrBs2 as a reporter. Seven proteins (XopAU, XopAV, XopAW, XopAP, XopAX, XopAK, and XopAD) harbored a functional translocation signal and their translocation relied on the HrpF translocon, indicating that they are bona fide T3S effectors. Remarkably, four of them belong to novel effector families. Inactivation of the xopAP gene reduced the severity of disease symptoms in infected plants. A decrease in cell death and chlorophyll content was observed in pepper leaves inoculated with the xopAP mutant as compared to the wild-type strain. However, populations of the xopAP mutant in infected leaves were similar in size to those of the wild-type bacteria, suggesting that the reduction in virulence was not due to an impaired bacterial growth.

Via Suayib Üstün, Jim Alfano
more...
No comment yet.
Rescooped by Nicolas Denancé from Plant Pathogenomics
Scoop.it!

mBio: A TALE of Transposition: Tn3-Like Transposons Play a Major Role in the Spread of Pathogenicity Determinants of Xanthomonas citri and Other Xanthomonads (2015)

mBio: A TALE of Transposition: Tn3-Like Transposons Play a Major Role in the Spread of Pathogenicity Determinants of Xanthomonas citri and Other Xanthomonads (2015) | Effectors and Plant Immunity | Scoop.it

Members of the genus Xanthomonas are among the most important phytopathogens. A key feature of Xanthomonas pathogenesis is the translocation of type III secretion system (T3SS) effector proteins (T3SEs) into the plant target cells via a T3SS. Several T3SEs and a murein lytic transglycosylase gene (mlt, required for citrus canker symptoms) are found associated with three transposition-related genes in Xanthomonas citri plasmid pXAC64. These are flanked by short inverted repeats (IRs). The region was identified as a transposon, TnXax1, with typical Tn3 family features, including a transposase and two recombination genes. Two 14-bp palindromic sequences within a 193-bp potential resolution site occur between the recombination genes. Additional derivatives carrying different T3SEs and other passenger genes occur in different Xanthomonas species. The T3SEs include transcription activator-like effectors (TALEs). Certain TALEs are flanked by the same IRs as found in TnXax1 to form mobile insertion cassettes (MICs), suggesting that they may be transmitted horizontally. A significant number of MICs carrying other passenger genes (including a number of TALE genes) were also identified, flanked by the same TnXax1 IRs and delimited by 5-bp target site duplications. We conclude that a large fraction of T3SEs, including individual TALEs and potential pathogenicity determinants, have spread by transposition and that TnXax1, which exhibits all of the essential characteristics of a functional transposon, may be involved in driving MIC transposition. We also propose that TALE genes may diversify by fork slippage during the replicative Tn3 family transposition. These mechanisms may play a crucial role in the emergence of Xanthomonas pathogenicity.


Via Kamoun Lab @ TSL
more...
No comment yet.
Rescooped by Nicolas Denancé from Plant-Microbe Symbioses
Scoop.it!

Plant denizens get the big-science treatment

Plant denizens get the big-science treatment | Effectors and Plant Immunity | Scoop.it

A plant may be rooted in place, but it is never lonely. There are bacteria in, on and near it, munching away on their host, on each other, on compounds in the soil. Amoebae dine on bacteria, nematodes feast on roots, insects devour fruit — with consequences for the chemistry of the soil, the taste of a leaf or the productivity of a crop.

 

From 30 June to 2 July, more than 200 researchers gathered in Washington DC for the first meeting of the Phytobiomes Initiative, an ambitious proposal to catalogue and characterize a plant’s most intimate associates and their impact on agriculture. By the end of the year, attendees hope to carve out a project that will apply this knowledge in ways that will appeal to funders in industry and government.

 

“We want to get more money,” says plant pathologist Linda Kinkel at the University of Minnesota in St Paul. “But beyond that, let’s just all try to talk the same language and come up with some shared goals.”

 

Leach coined the term phytobiome in 2013,at a retreat about food security. She defines the phytobiome broadly, to encompass microbes, insects, nematodes and plants as well as the abiotic factors that influence all these.

 

Since then, she has visited companies, funding agencies and universities to call for a unifying phytobiomes initiative. She has teamed up with Kellye Eversole, a consultant based in Bethesda, Maryland, and the co-owner of a small family farm in Oklahoma, who has experience working on large agricultural genomics projects, including the US National Plant Genome Initiative. That initiative was launched in 1998 and continues to crank out databases and other tools for analysing plant genomes.

 

Leach hopes that the Phytobiomes Initiative will leave a similar legacy, but she is mindful that federal funding has tightened considerably since 1998. Still, she notes that the project can build on several emerging trends in agriculture. Industry has shown renewed interest in boosting plant growth by manipulating associated microbes (Nature 504, 199; 2013). Companies and farmers are also investing in ‘precision agriculture’, which uses high-tech monitors to track conditions in a field or even around individual plants, allowing farmers to water and fertilize in exactly the right places.

 

High-tech future

 

Eversole foresees a day when tractors will carry dipstick-like gauges that provide a snapshot of the microbial community in the soil. Data from the Phytobiomes Initiative would then help farmers to manipulate that community to their advantage, she says.

 

But first, the initiative needs to standardize protocols and metrics, the meeting’s attendees determined. Kinkel says that efforts are likely to focus initially on cataloguing microbes and insects and their interactions with different crops and habitats. “We’re where plant biologists were 150 years ago,” she says. “We’re still trying to inventory things.”

 

Work has already begun along these lines: for example, a group at the International Rice Research Institute in Los Baños in the Philippines is fishing for microbial DNA in data discarded from an effort to sequence the rice genome. The goal is to determine which microbes prefer which strains of the crop.

 

Kinkel, meanwhile, has begun experimenting with manipulating carbon levels in the soil to alter the microbial population, with the aim of improving plant productivity. “If we can understand better who lives on and within plants, we have the potential to manage them to have healthier, more resilient plants,” she says.

 

Projects such as these would move faster under an organized, cohesive framework, says Sarah Lebeis, a microbiologist at the University of Tennessee in Knoxville who is studying how plants manipulate microbial communities by secreting antibiotics into the soil. “Right now we’re working as individuals,” she says. “Having an initiative will give us focus and hopefully we’ll progress further, faster, better.”


Via Kamoun Lab @ TSL, Jean-Michel Ané
more...
No comment yet.
Scooped by Nicolas Denancé
Scoop.it!

Front. Plant Sci.: TAL effectors and activation of predicted host targets distinguish Asian from African strains of the rice pathogen Xanthomonas oryzae pv. oryzicola while strict conservation sugg...

Front. Plant Sci.: TAL effectors and activation of predicted host targets distinguish Asian from African strains of the rice pathogen Xanthomonas oryzae pv. oryzicola while strict conservation sugg... | Effectors and Plant Immunity | Scoop.it

Xanthomonas oryzae pv. oryzicola (Xoc) causes the increasingly important disease bacterial leaf streak of rice (BLS) in part by type III delivery of repeat-rich transcription activator-like (TAL) effectors to upregulate host susceptibility genes. By pathogen whole genome, single molecule, real-time sequencing and host RNA sequencing, we compared TAL effector content and rice transcriptional responses across 10 geographically diverse Xoc strains. TAL effector content is surprisingly conserved overall, yet distinguishes Asian from African isolates. Five TAL effectors are conserved across all strains. In a prior laboratory assay in rice cv. Nipponbare, only two contributed to virulence in strain BLS256 but the strict conservation indicates all five may be important, in different rice genotypes or in the field. Concatenated and aligned, TAL effector content across strains largely reflects relationships based on housekeeping genes, suggesting predominantly vertical transmission. Rice transcriptional responses did not reflect these relationships, and on average, only 28% of genes upregulated and 22% of genes downregulated by a strain are up- and downregulated (respectively) by all strains. However, when only known TAL effector targets were considered, the relationships resembled those of the TAL effectors. Toward identifying new targets, we used the TAL effector-DNA recognition code to predict effector binding elements in promoters of genes upregulated by each strain, but found that for every strain, all upregulated genes had at least one. Filtering with a classifier we developed previously decreases the number of predicted binding elements across the genome, suggesting that it may reduce false positives among upregulated genes. Applying this filter and eliminating genes for which upregulation did not strictly correlate with presence of the corresponding TAL effector, we generated testable numbers of candidate targets for four of the five strictly conserved TAL effectors.

 

Wilkins KE, Booher NJ, Wang L and Bogdanove AJ

 

 

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

5th Xanthomonas Genomics Conference 2015 - July 8 - 11, 2015. Bogotá, Colombia

5th Xanthomonas Genomics Conference 2015 - July 8 - 11, 2015. Bogotá, Colombia | Effectors and Plant Immunity | Scoop.it

The final program of the XGC 2015... sounds really promising!

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

Front. Plant Sci.: Comparative genomics of a cannabis pathogen reveals insight into the evolution of pathogenicity in Xanthomonas (2015)

Front. Plant Sci.: Comparative genomics of a cannabis pathogen reveals insight into the evolution of pathogenicity in Xanthomonas (2015) | Effectors and Plant Immunity | Scoop.it

Pathogenic bacteria in the genus Xanthomonas cause diseases on over 350 plant species, including cannabis (Cannabis sativa L.). Because of regulatory limitations, the biology of the Xanthomonas-cannabis pathosystem remains largely unexplored. To gain insight into the evolution of Xanthomonas strains pathogenic to cannabis, we sequenced the genomes of two geographically distinct Xanthomonas strains, NCPPB 3753 and NCPPB 2877, which were previously isolated from symptomatic plant tissue in Japan and Romania. Comparative multilocus sequence analysis of housekeeping genes revealed that they belong to Group 2, which comprises most of the described species of Xanthomonas. Interestingly, both strains lack the Hrp Type III secretion system and do not contain any of the known Type III effectors. Yet their genomes notably encode two key Hrp pathogenicity regulators HrpG and HrpX, and hrpG and hrpX are in the same genetic organization as in the other Group 2 xanthomonads. Promoter prediction of HrpX-regulated genes suggests the induction of an aminopeptidase, a lipase and two polygalacturonases upon plant colonization, similar to other plant-pathogenic xanthomonads. Genome analysis of the distantly related Xanthomonas maliensis strain 97M, which was isolated from a rice leaf in Mali, similarly demonstrated the presence of HrpG, HrpX and a HrpX-regulated polygalacturonase, and the absence of the Hrp Type III secretion system and known Type III effectors. Given the observation that some Xanthomonas strains across distinct taxa do not contain hrpG and hrpX, we speculate a stepwise evolution of pathogenicity, which involves (i) acquisition of key regulatory genes and cell wall-degrading enzymes, followed by (ii) acquisition of the Hrp type III secretion system, which is ultimately accompanied by (iii) successive acquisition of type III effectors.

 

Jacobs JM, Pesce C, Lefeuvre P and Koebnik R

more...
No comment yet.