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Ralstonia solanacearum of tomato
Ralstonia solanacearum of tomato
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Rescooped by tianxing84 from Effectors and Plant Immunity
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BMC Genomics: Repertoire, unified nomenclature and evolution of the Type III effector gene set in the Ralstonia solanacearum species complex (2013)

BMC Genomics: Repertoire, unified nomenclature and evolution of the Type III effector gene set in the Ralstonia solanacearum species complex (2013) | Ralstonia solanacearum of tomato | Scoop.it

Ralstonia solanacearum is a soil-borne beta-proteobacterium that causes bacterial wilt disease in many food crops and is a major problem for agriculture in intertropical regions. R. solanacearum is a heterogeneous species, both phenotypically and genetically, and is considered as a species complex. Pathogenicity of R. solanacearum relies on the Type III secretion system that injects Type III effector (T3E) proteins into plant cells. T3E collectively perturb host cell processes and modulate plant immunity to enable bacterial infection. We provide the catalogue of T3E in the R. solanacearum species complex, as well as candidates in newly sequenced strains. 95 T3E orthologous groups were defined on phylogenetic bases and ordered using a uniform nomenclature. This curated T3E catalog is available on a public website and a bioinformatic pipeline has been designed to rapidly predict T3E genes in newly sequenced strains. Systematical analyses were performed to detect lateral T3E gene transfer events and identify T3E genes under positive selection. Our analyses also pinpoint the RipF translocon proteins as major discriminating determinants among the phylogenetic lineages. Establishment of T3E repertoires in strains representatives of the R. solanacearum biodiversity allowed determining a set of 22 T3E present in all the strains but provided no clues on host specificity determinants. The definition of a standardized nomenclature and the optimization of predictive tools will pave the way to understanding how variation of these repertoires is correlated to the diversification of this species complex and how they contribute to the different strain pathotypes. 

 

Nemo Peeters, Sébastien Carrère, Maria Anisimova, Laure Plener, Anne-Claire Cazalé and Stephane Genin

 

Database interface: https://iant.toulouse.inra.fr/bacteria/annotation/cgi/ralso_effectome/ralso_effectome.cgi


Via Nicolas Denancé
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MPMI: A novel, sensitive method to evaluate potato germplasm for bacterial wilt resistance using a luminescent Ralstonia solanacearum reporter strain (2013)

MPMI: A novel, sensitive method to evaluate potato germplasm for bacterial wilt resistance using a luminescent Ralstonia solanacearum reporter strain (2013) | Ralstonia solanacearum of tomato | Scoop.it

Several breeding programs are under way to introduce resistance to bacterial wilt caused by Ralstonia solanacearum in solanaceous crops. The lack of screening methods allowing easy measurement of pathogen colonization and the inability to detect latent (i.e. symptomless) infections are major limitations when evaluating resistance to this disease in plant germplasm. We describe a new method to study the interaction between R. solanacearum and potato germplasm that overcomes these restrictions. The R. solanacearum strain UY031 was genetically modified to constitutively generate light from a synthetic luxCDABE operon stably inserted in its chromosome. Colonization of this reporter strain on different potato accessions was followed using life imaging. Bacterial detection in planta by this non-disruptive system correlated with the development of wilting symptoms. In addition, we demonstrated that quantitative detection of the recombinant strain using a luminometer can identify latent infections on symptomless potato plants. We have developed a novel, unsophisticated and accurate method for high-throughput evaluation of pathogen colonization in plant populations. We applied this method to compare the behavior of potato accessions with contrasting resistance to R. solanacearum. This new system will be especially useful to detect latency in symptomless parental lines before their inclusion in long-term breeding programs for disease resistance.


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Rescooped by tianxing84 from Plants&Bacteria
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Gene transcription analysis during interaction between potato and Ralstonia solanacearum

Gene transcription analysis during interaction between potato and Ralstonia solanacearum | Ralstonia solanacearum of tomato | Scoop.it

Scooped from: Russian Journal of Plant Physiology, 2010

Authors: G. C. Li, L. P. Jin, X. W. Wang, K. Y. Xie, Y. Yang, E. A. G. van  der Vossen, S. W. Huang and D. Y. Qu

 

Summary:

Bacterial wilt (BW) caused by Ralstonia solanacearum (Rs) is an important quarantine disease that spreads worldwide and infects hundreds of plant species. The BW defense response of potato is a complicated continuous process, which involves transcription of a battery of genes. The molecular mechanisms of potato-Rs interactions are poorly understood. In this study, we combined suppression subtractive hybridization and macroarray hybridization to identify genes that are differentially expressed during the incompatible interaction between Rs and potato. In total, 302 differentially expressed genes were identified and classified into 12 groups according to their putative biological functions. Of 302 genes, 81 were considered as Rs resistance-related genes based on the homology to genes of known function, and they have putative roles in pathogen recognition, signal transduction, transcription factor functioning, hypersensitive response, systemic acquired resistance, and cell rescue and protection. Additionally, 50 out of 302 genes had no match or low similarity in the NCBI databases, and they may represent novel genes. Of seven interesting genes analyzed via RNA gel blot and semi-quantitative RT-PCR, six were induced, one was suppressed, and all had different transcription patterns. The results demonstrate that the response of potato against Rs is rapid and involves the induction of numerous various genes. The genes identified in this study add to our knowledge of potato resistance to Rs.


Via Freddy Monteiro
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Freddy Monteiro's comment, June 28, 2013 3:21 PM
See also these related publications: http://sco.lt/61d49x
Freddy Monteiro's comment, June 28, 2013 3:25 PM
and http://mbio.asm.org/content/3/4/e00114-12.full
Rescooped by tianxing84 from Plants&Bacteria
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Ethylene emission and PR protein synthesis in ACC deaminase producing Methylobacterium spp. inoculated tomato plants (Lycopersicon esculentum Mill.) challenged with Ralstonia solanacearum under gre...

Ethylene emission and PR protein synthesis in ACC deaminase producing Methylobacterium spp. inoculated tomato plants (Lycopersicon esculentum Mill.) challenged with Ralstonia solanacearum under gre... | Ralstonia solanacearum of tomato | Scoop.it

Scooped from: Plant Physiology and Biochemistry, 2013

Authors: Woojong Yima, Sundaram Seshadrib, Kiyoon Kima, Gillseung Leec, Tongmin Sa

 

Summary:

Bacteria of genus Methylobacterium have been found to promote plant growth and regulate the level of ethylene in crop plants. This work is aimed to test the induction of defense responses in tomato against bacterial wilt by stress ethylene level reduction mediated by the ACC deaminase activity of Methylobacterium strains. Under greenhouse conditions, the disease index value in Methylobacterium sp. inoculated tomato plants was lower than control plants. Plants treated with Methylobacterium sp. challenge inoculated with Ralstonia solanacearum (RS) showed significantly reduced disease symptoms and lowered ethylene emission under greenhouse condition. The ACC and ACO (1-aminocyclopropane-1-carboxylate oxidase) accumulation in tomato leaves were significantly reduced with Methylobacterium strains inoculation. While ACC oxidase gene expression was found higher in plants treated with R. solanacearum than Methylobacterium sp. treatment, PR proteins related to induced systemic resistance like β-1,3-glucanase, PAL, PO and PPO were increased in Methylobacterium sp. inoculated plants. A significant increase in β-1,3-glucanase and PAL gene expression was found in all the Methylobacterium spp. treatments compared to the R. solanacearum treatment. This study confirms the activity of Methylobacterium sp. in increasing the defense enzymes by modulating the ethylene biosynthesis pathway and suggests the use of methylotrophic bacteria as potential biocontrol agents in tomato cultivation.


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Mol. Plant Pathol.: Ralstonia solanacearum, a widespread bacterial plant pathogen in the post-genomic era (2013)

Mol. Plant Pathol.: Ralstonia solanacearum, a widespread bacterial plant pathogen in the post-genomic era (2013) | Ralstonia solanacearum of tomato | Scoop.it

Summary

Ralstonia solanacearum is a soil-borne bacterium causing the widespread disease known as bacterial wilt. Ralstonia solanacearum is also the causal agent of Moko disease of banana and brown rot of potato. Since the last R. solanacearum pathogen profile was published 10 years ago, studies concerning this plant pathogen have taken a genomic and post-genomic direction. This was pioneered by the first sequenced and annotated genome for a major plant bacterial pathogen and followed by many more genomes in subsequent years. All molecular features studied now have a genomic flavour. In the future, this will help in connecting the classical field of pathology and diversity studies with the gene content of specific strains. In this review, we summarize the recent research on this bacterial pathogen, including strain classification, host range, pathogenicity determinants, regulation of virulence genes, type III effector repertoire, effector-triggered immunity, plant signalling in response to R. solanacearum, as well as a review of different new pathosystems.

Taxonomy

Bacteria; Proteobacteria; β subdivision; Ralstonia group; genus Ralstonia.

Disease symptoms

Ralstonia solanacearum is the agent of bacterial wilt of plants, characterized by a sudden wilt of the whole plant. Typically, stem cross-sections will ooze a slimy bacterial exudate. In the case of Moko disease of banana and brown rot of potato, there is also visible bacterial colonization of banana fruit and potato tuber.

Disease control

As a soil-borne pathogen, infected fields can rarely be reused, even after rotation with nonhost plants. The disease is controlled by the use of resistant and tolerant plant cultivars. The prevention of spread of the disease has been achieved, in some instances, by the application of strict prophylactic sanitation practices.

Useful websites

Stock centre: International Centre for Microbial Resources—French Collection for Plant-associated Bacteria CIRM-CFBP, IRHS UMR 1345 INRA-ACO-UA, 42 rue Georges Morel, 49070 Beaucouzé Cedex, France, http://www.angers-nantes.inra.fr/cfbp/. Ralstonia Genome browser: https://iant.toulouse.inra.fr/R.solanacearum. GMI1000 insertion mutant library: https://iant.toulouse.inra.fr/R.solanacearumGMI1000/GenomicResources. MaGe Genome Browser: https://www.genoscope.cns.fr/agc/microscope/mage/viewer.php

 

Nemo Peeters, Alice Guidot, Fabienne Vailleau, and Marc Valls


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Phytopathogen type III effectors as probes of biological systems - Microbial Biotechnology

Phytopathogen type III effectors as probes of biological systems - Microbial Biotechnology | Ralstonia solanacearum of tomato | Scoop.it

Amy Huei-Yi Lee; Maggie A. Middleton; David S. Guttman; Darrell Desveaux

 

Summary:

Bacterial phytopathogens utilize a myriad of virulence factors to modulate their plant hosts in order to promote successful pathogenesis. One potent virulence strategy is to inject these virulence proteins into plant cells via the type III secretion system. Characterizing the host targets and the molecular mechanisms of type III secreted proteins, known as effectors, has illuminated our understanding of eukaryotic cell biology. As a result, these effectors can serve as molecular probes to aid in our understanding of plant cellular processes, such as immune signalling, vesicle trafficking, cytoskeleton stability and transcriptional regulation. Furthermore, given that effectors directly and specifically interact with their targets within plant cells, these virulence proteins have enormous biotechnological potential for manipulating eukaryotic systems.


Via Freddy Monteiro
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Freddy Monteiro's curator insight, February 27, 2013 12:34 AM

For quite some time effector proteins started to be regarded as potential molecular tools to investigate cellular processes. This is an expanding field and I hope effector biology may help on our understanding of plant biology and molecular evolution dynamics.

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The importance of colony morphology, and why TZC should be ALWAYS used when working with Ralstonia solanacearum


Via Freddy Monteiro
tianxing84's insight:

For quite some time now I was aware of the different phenotypes you can observe in a plate when you streak Ralstonia solanacearum. Just ecause I was correctly taught, I quickly learnt which clones to select to proceed with my experiments. However... I failed to provide an explanation to colleagues insisting on not using TZC. They claimed that colony morphology was quite obvious without it. I disagreed at the time, and I still do, but now I have a handout for all those with white colonies on their plates.

 

I am finally finding and writing important things on my thesis. And I want it to contain this kind of information as well... because not only my experiments were useful. Those obtained before 1954 may be more important to our labs nowadays.

 

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Freddy Monteiro's curator insight, January 8, 2013 8:15 AM

For quite some time now I was aware of the different phenotypes you can observe in a plate when you streak Ralstonia solanacearum. Just ecause I was correctly taught, I quickly learnt which clones to select to proceed with my experiments. However... I failed to provide an explanation to colleagues insisting on not using TZC. They claimed that colony morphology was quite obvious without it. I disagreed at the time, and I still do, but now I have a handout for all those with white colonies on their plates.

 

I am finally finding and writing important things on my thesis. And I want it to contain this kind of information as well... because not only my experiments were useful. Those obtained before 1954 may be more important to our labs nowadays.

 

Rescooped by tianxing84 from Plants&Bacteria
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Overexpression of a Chinese cabbage BrERF11 transcription factor enhances disease resistance to Ralstonia solanacearum in tobacco

Overexpression of a Chinese cabbage BrERF11 transcription factor enhances disease resistance to Ralstonia solanacearum in tobacco | Ralstonia solanacearum of tomato | Scoop.it

May we see the ethylene production story taken to a new level soon! Perhaps by providing a resistance strategy for R. solanacearum. This paper branches my mind out to other experiements that could be performed =)

 

Summary:

Ethylene-responsive factors (ERFs) play diverse roles in plant growth, developmental processes and stress responses. However, the roles and underlying mechanism of ERFs remain poorly understood, especially in non-model plants. In this study, a full length cDNA of ERF gene was isolated from the cDNA library of Chinese cabbage. According to sequence alignment, we found a highly conservative AP2/ERF domain, two nuclear localization signals, and an ERF-associated Amphiphilic Repression (EAR) motif in its C-terminal region. It belonged to VIIIa group ERFs sharing the highest sequence identity with AtERF11 in all of the ERFs in Arabidopsis and designated BrERF11. BrERF11-green fluorescence protein (GFP) transient expressed in onion epidermis cells localized to the nucleus. The transcript levels of BrERF11 were induced by exogenous salicylic acid (SA), methyl jasmonate (MeJA), ethephon (ETH), and hydrogen peroxide (H2O2). Constitutive expression of BrERF11 enhanced tolerance to Ralstonia solanacearum infection in transgenic tobacco plants, which was coupled with hypersensitive response (HR), burst of H2O2 and upregulation of defense-related genes including HR marker genes, SA-, JA-dependent pathogen-related genes and ET biosynthesis associated genes and downregulation of CAT1, suggesting BrERF11 may participate in pathogen-associated molecular pattern (PAMP)- and effector-triggered immunity (PTI and ETI) mediated by SA-, JA- and ET-dependent signaling mechanisms.


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Science: Tricking the Guard: Exploiting Plant Defense for Disease Susceptibility

Science: Tricking the Guard: Exploiting Plant Defense for Disease Susceptibility | Ralstonia solanacearum of tomato | Scoop.it

Abstract

Typically, pathogens deploy virulence effectors to disable defense. Plants defeat effectors with resistance proteins that guard effector targets. Here, we show that a pathogen exploits a resistance protein by activating it to confer susceptibility. Interactions of victorin, an effector produced by the necrotrophic fungus Cochliobolus victoriae, TRX-h5, a defense-associated thioredoxin, and LOV1, an Arabidopsis susceptibility protein, recapitulate the guard mechanism of plant defense. In LOV1's absence, victorin inhibits TRX-h5 resulting in compromised defense but not disease by C. victoriae. In LOV1's presence, victorin binding to TRX-h5 activates LOV1 and elicits a resistance-like response that confers disease susceptibility. We propose that victorin is or mimics a conventional pathogen virulence effector that was defeated by LOV1 and confers virulence to C. victoriae solely because it incites defense.


Via Suayib Üstün, CP
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The Grower: Transgenic tomato withstands bacterial spot, yields more fruit (2012)

The Grower: Transgenic tomato withstands bacterial spot, yields more fruit (2012) | Ralstonia solanacearum of tomato | Scoop.it

When a gene from bell and hot peppers is inserted into tomatoes, it not only imparts resistance to bacterial spot—a devastating tomato disease—it also bumps up yields.


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Arabidopsis wat1 (walls are thin1)-mediated resistance to the bacterial vascular pathogen R. solanacearum is accompanied by cross-regulation of salicylic acid and tryptoph metabolism

Arabidopsis wat1 (walls are thin1)-mediated resistance to the bacterial vascular pathogen R. solanacearum is accompanied by cross-regulation of salicylic acid and tryptoph metabolism | Ralstonia solanacearum of tomato | Scoop.it

Our friend Nicolas Denancé ( http://www.scoop.it/u/nicolas-denance#pg=1&mi=topics&si=curated&panel=followedPanel ) provides us with this very interesting report.

 

I am posting this with great joy for this accomplishment, while still printing the article, to read at home.

 

 

Summary
The inactivation of Arabidopsis WAT1 (Walls Are Thin1), a gene required for secondary cell wall deposition, conferred a broad-spectrum resistance to vascular pathogens, including the bacteria Ralstonia solanacearum and Xanthomonas campestris pv. campestris, and the fungi, Verticillium dahliae and V. albo-atrum. The introduction of NahG, the bacterial salicylic acid (SA)-degrading salicylate hydroxylase gene, into wat1 restored full susceptibility to both R. solanacearum and X. campestris pv. campestris. Moreover, SA content was constitutively higher in wat1 roots, further supporting a role for SA in wat1-mediated resistance to vascular pathogens. By combining transcriptomic and metabolomic data, we demonstrated a general repression of indole metabolism in wat1-1 roots as shown by a constitutive down-regulation of several genes encoding proteins along the indole glucosinolate (IGS) biosynthetic pathway and reduced amounts of tryptophan (Trp), IAA and neoglucobrassicin, the major form of IGS in roots. Furthermore, wat1 susceptibility to R. solanacearum was partially restored when crossed with either trp5, an overaccumulator of Trp or Pro35S:AFB1-myc in which IAA signaling is constitutively activated. Our original hypothesis placed cell wall modifications at the heart of wat1 resistance phenotype. However, the results presented here point to a mechanism involving root-localized, metabolic channeling away from indole metabolites to SA as a central feature of wat1 resistance to R. solanacearum.

 

 

Nicolas Denancé*, Philippe Ranocha*, Nicolas Oria, Xavier Barlet, Marie-Pierre Rivière, Koste A. Yadeta, Laurent Hoffmann, François Perreau, Gilles Clément, Alessandra Maia-Grondard, Grardy C.M. van den Berg, Bruno Savelli, Sylvie Fournier, Yann Aubert, Sandra Pelletier, Bart P.H.J. Thomma, Antonio Molina, Lise Jouanin, Yves Marco, Deborah Goffner

 

 

 


Via Nicolas Denancé, Freddy Monteiro
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BMC Genomics: Repertoire, unified nomenclature and evolution of the Type III effector gene set in the Ralstonia solanacearum species complex (2013)

BMC Genomics: Repertoire, unified nomenclature and evolution of the Type III effector gene set in the Ralstonia solanacearum species complex (2013) | Ralstonia solanacearum of tomato | Scoop.it

Background. Ralstonia solanacearum is a soil-borne beta-proteobacterium that causes bacterial wilt disease in many food crops and is a major problem for agriculture in intertropical regions. R. solanacearum is a heterogeneous species, both phenotypically and genetically, and is considered as a species complex. Pathogenicity of R. solanacearum relies on the Type III secretion system that injects Type III effector (T3E) proteins into plant cells. T3E collectively perturb host cell processes and modulate plant immunity to enable bacterial infection.

 

Results. We provide the catalogue of T3E in the R. solanacearum species complex, as well as candidates in newly sequenced strains. 94 T3E orthologous groups were defined on phylogenetic bases and ordered using a uniform nomenclature. This curated T3E catalog is available on a public website and a bioinformatic pipeline has been designed to rapidly predict T3E genes in newly sequenced strains. Systematical analyses were performed to detect lateral T3E gene transfer events and identify T3E genes under positive selection. Our analyses also pinpoint the RipF translocon proteins as major discriminating determinants among the phylogenetic lineages.

 

Conclusions. Establishment of T3E repertoires in strains representatives of the R. solanacearum biodiversity allowed determining a set of 22 T3E present in all the strains but provided no clues on host specificity determinants. The definition of a standardized nomenclature and the optimization of predictive tools will pave the way to understanding how variation of these repertoires is correlated to the diversification of this species complex and how they contribute to the different strain pathotypes.


Via Kamoun Lab @ TSL
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Nat. Commun.: Plant immune response to pathogens differs with changing temperatures (2013)

Nat. Commun.: Plant immune response to pathogens differs with changing temperatures (2013) | Ralstonia solanacearum of tomato | Scoop.it

Temperature fluctuation is a key determinant for microbial invasion and host evasion. In contrast to mammals that maintain constant body temperature, plant temperature oscillates on a daily basis. It remains elusive how plants operate inducible defenses in response to temperature fluctuation. Here we report that ambient temperature changes lead to pronounced shifts of the following two distinct plant immune responses: pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). Plants preferentially activate ETI signaling at relatively low temperatures (10–23 °C), whereas they switch to PTI signaling at moderately elevated temperatures (23–32 °C). The Arabidopsis arp6 and hta9hta11 mutants, phenocopying plants grown at elevated temperatures, exhibit enhanced PTI and yet reduced ETI responses. As the secretion of bacterial effectors favours low temperatures, whereas bacteria multiply vigorously at elevated temperatures accompanied with increased microbe-associated molecular pattern production, our findings suggest that temperature oscillation might have driven dynamic co-evolution of distinct plant immune signaling responding to pathogen physiological changes.

 

Cheng Cheng, Xiquan Gao, Baomin Feng, Jen Sheen, Libo Shan & Ping He


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Ethylene emission and PR protein synthesis in ACC deaminase producing Methylobacterium spp. inoculated tomato plants (Lycopersicon esculentum Mill.) challenged with Ralstonia solanacearum under gre...

Ethylene emission and PR protein synthesis in ACC deaminase producing Methylobacterium spp. inoculated tomato plants (Lycopersicon esculentum Mill.) challenged with Ralstonia solanacearum under gre... | Ralstonia solanacearum of tomato | Scoop.it

Scooped from: Plant Physiology and Biochemistry, 2013

Authors: Woojong Yima, Sundaram Seshadrib, Kiyoon Kima, Gillseung Leec, Tongmin Sa

 

Summary:

Bacteria of genus Methylobacterium have been found to promote plant growth and regulate the level of ethylene in crop plants. This work is aimed to test the induction of defense responses in tomato against bacterial wilt by stress ethylene level reduction mediated by the ACC deaminase activity of Methylobacterium strains. Under greenhouse conditions, the disease index value in Methylobacterium sp. inoculated tomato plants was lower than control plants. Plants treated with Methylobacterium sp. challenge inoculated with Ralstonia solanacearum (RS) showed significantly reduced disease symptoms and lowered ethylene emission under greenhouse condition. The ACC and ACO (1-aminocyclopropane-1-carboxylate oxidase) accumulation in tomato leaves were significantly reduced with Methylobacterium strains inoculation. While ACC oxidase gene expression was found higher in plants treated with R. solanacearum than Methylobacterium sp. treatment, PR proteins related to induced systemic resistance like β-1,3-glucanase, PAL, PO and PPO were increased in Methylobacterium sp. inoculated plants. A significant increase in β-1,3-glucanase and PAL gene expression was found in all the Methylobacterium spp. treatments compared to the R. solanacearum treatment. This study confirms the activity of Methylobacterium sp. in increasing the defense enzymes by modulating the ethylene biosynthesis pathway and suggests the use of methylotrophic bacteria as potential biocontrol agents in tomato cultivation.


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Breaking the DNA-binding code of Ralstonia solanacearum TAL effectors provides new possibilities to generate plant resistance genes against bacterial wilt disease - New Phytologist

(Via T. Lahaye & T. Schreiber) De Lange et al 2013 Ralstonia solanacearum is a devastating bacterial phytopathogen with a broad host range. Ralstonia solanacearum injected effector proteins (Rips) are key to the successful invasion of host plants. We have characterized Brg11(hrpB-regulated 11), the first identified member of a class of Rips with high sequence similarity to the transcription activator-like (TAL) effectors of Xanthomonas spp., collectively termed RipTALs. Fluorescence microscopy of in planta expressed RipTALs showed nuclear localization. Domain swaps between Brg11 and Xanthomonas TAL effector (TALE) AvrBs3 (avirulence protein triggering Bs3 resistance) showed the functional interchangeability of DNA-binding and transcriptional activation domains. PCR was used to determine the sequence of brg11 homologs from strains infecting phylogenetically diverse host plants. Brg11 localizes to the nucleus and activates promoters containing a matching effector-binding element (EBE). Brg11 and homologs preferentially activate promoters containing EBEs with a 5′ terminal guanine, contrasting with the TALE preference for a 5′ thymine. Brg11 and other RipTALs probably promote disease through the transcriptional activation of host genes. Brg11 and the majority of homologs identified in this study were shown to activate similar or identical target sequences, in contrast to TALEs, which generally show highly diverse target preferences. This information provides new options for the engineering of plants resistant to R. solanacearum.


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Pathogenomics of the Ralstonia solanacearum Species Complex - Annual Review of Phytopathology

Pathogenomics of the Ralstonia solanacearum Species Complex - Annual Review of Phytopathology | Ralstonia solanacearum of tomato | Scoop.it

Stéphane Genin and Timothy P. Denny

 

A great review to catch up with the genomic analysis of the Ralstonia solanacearum scpecies complex, pathogen evolution and the sofisticated network of regulators controlling pathogenesis.

It comes just in the right time, in my opinion. Both, as stated by the authors, to refine functional studies, but also to provide a refreshed and comprehensive state of the art in the field.

 

Abstract:

Ralstonia solanacearum is a major phytopathogen that attacks many crops and other plants over a broad geographical range. The extensive genetic diversity of strains responsible for the various bacterial wilt diseases has in recent years led to the concept of an R. solanacearum species complex. Genome sequencing of more than 10 strains representative of the main phylogenetic groups has broadened our knowledge of the evolution and speciation of this pathogen and led to the identification of novel virulence-associated functions. Comparative genomic analyses are now opening the way for refined functional studies. The many molecular determinants involved in pathogenicity and host-range specificity are described, and we also summarize current understanding of their roles in pathogenesis and how their expression is tightly controlled by an intricate virulence regulatory network.


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Freddy Monteiro's curator insight, February 24, 2013 11:15 AM

I hadn't notice this sentence before:

"Even though the known regulatory networks in R. solanacearum are already quite complex, you ain’t seen nothin’ yet!"

 

 

Amanzing!!

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New Phytologist: Medicago truncatula DNF2 is a PI-PLC-XD-containing protein required for bacteroid persistence and prevention of nodule early senescence and defense-like reactions (2012)

New Phytologist: Medicago truncatula DNF2 is a PI-PLC-XD-containing protein required for bacteroid persistence and prevention of nodule early senescence and defense-like reactions (2012) | Ralstonia solanacearum of tomato | Scoop.it

 

Medicago truncatula and Sinorhizobium meliloti form a symbiotic association resulting in the formation of nitrogen-fixing nodules. Nodule cells contain large numbers of bacteroids which are differentiated, nitrogen-fixing forms of the symbiotic bacteria. In the nodules, symbiotic plant cells home and maintain hundreds of viable bacteria. In order to better understand the molecular mechanism sustaining the phenomenon, we searched for new plant genes required for effective symbiosis.We used a combination of forward and reverse genetics approaches to identify a gene required for nitrogen fixation, and we used cell and molecular biology to characterize the mutant phenotype and to gain an insight into gene function.The symbiotic gene DNF2 encodes a putative phosphatidylinositol phospholipase C-like protein. Nodules formed by the mutant contain a zone of infected cells reduced to a few cell layers. In this zone, bacteria do not differentiate properly into bacteroids. Furthermore, mutant nodules senesce rapidly and exhibit defense-like reactions.This atypical phenotype amongst Fix− mutants unravels dnf2 as a new actor of bacteroid persistence inside symbiotic plant cells.


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Gene-for-gene tolerance to bacterial wilt in Arabidopsis, in MPMI

Gene-for-gene tolerance to bacterial wilt in Arabidopsis, in MPMI | Ralstonia solanacearum of tomato | Scoop.it

Via Freddy Monteiro
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Freddy Monteiro's curator insight, December 14, 2012 4:12 AM

Are we getting close to the genetic basis of R. solanacearum latents infections ??

 

I do not know how far can we go when comparing tolerance with latency... but I like the insights you can get from this particular report

 

 

Summary:

Bacterial wilt caused by Ralstonia solanacearum is a disease of widespread economic importance that affects numerous plant species including Arabidopsis thaliana. We describe a pathosystem between A. thaliana and a biovar 3 phylotype I strain BCCF402 of R. solanacearum isolated from Eucalyptus trees. A. thaliana accession Be 0 was susceptible and accession Kil 0 was tolerant. Kil 0 exhibited no wilting symptoms and no significant reduction in fitness (biomass, seed yield and germination efficiency) after inoculation with R. solanacearum BCCF402, despite high bacterial numbers in planta. This was in contrast to the well-characterised resistance response in the accession Nd-1, which limits bacterial multiplication at early stages of infection and does not wilt. R. solanacearum BCCF402 was highly virulent since the susceptible accession Be 0 was completely wilted after inoculation. Genetic analyses, allelism studies with Nd 1, and RRS1 CAPS marker analysis showed that the tolerance phenotype in Kil 0 was dependent upon the resistance gene RRS1. Knockout and complementation studies of the R. solanacearum BCCF402 effector PopP2 confirmed that the tolerance response in Kil 0 was dependent upon the RRS1-PopP2 interaction. Our data indicate that the gene-for-gene interaction between RRS1 and PopP2 can contribute to tolerance, as well as resistance, which makes it a useful model system for evolutionary studies of the arms race between plants and bacterial pathogens. In addition, the results alert biotechnologists to the risk that deployment of RRS1 in transgenic crops may result in persistence of the pathogen in the field.

Rescooped by tianxing84 from Plants and Microbes
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Current Opinion Plant Biol: Plants and pathogens: putting infection strategies and defence mechanisms on the map (2012)

Current Opinion Plant Biol: Plants and pathogens: putting infection strategies and defence mechanisms on the map (2012) | Ralstonia solanacearum of tomato | Scoop.it

All plant organs are vulnerable to colonisation and molecular manipulation by microbes. When this interaction allows proliferation of the microbe at the expense of the host, the microbe can be described as a pathogen. In our attempts to understand the full nature of the interactions that occur between a potential pathogen and its host, various aspects of the molecular mechanisms of infection and defence have begun to be characterised. There is significant variation in these mechanisms. While previous research has examined plant–pathogen interactions with whole plant/organ resolution, the specificity of infection strategies and changes in both gene expression and protein localisation of immune receptors upon infection suggest there is much to be gained from examination of plant-microbe interactions at the cellular level.


Via Nicolas Denancé, Mary Williams, S&M, Kamoun Lab @ TSL
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Transcriptome Analysis of Quantitative Resistance-Specific Response upon Ralstonia solanacearum Infection in Tomato

Transcriptome Analysis of Quantitative Resistance-Specific Response upon Ralstonia solanacearum Infection in Tomato | Ralstonia solanacearum of tomato | Scoop.it

Abstract Top

Bacterial wilt, caused by the soil-borne bacterium Ralstonia solanacearum, is a lethal disease of tomato, but the molecular mechanisms of the host resistance responses to R. solanacearum remain unclear. In this study, we report the first work describing the transcriptome of cultivar resistance and susceptible tomato cultivar after inoculation with R. solanacearum. To elucidate the characteristics of resistance early in the interaction, we analyzed microarrays for resistant cultivar LS-89 and susceptible cultivar Ponderosa 1 day after stem inoculation. No change in gene expression was detected for Ponderosa, but expression levels of over 140 genes, including pathogenesis-related, hormone signaling and lignin biosynthesis genes, increased in LS-89. Expression of β-1,3-glucanase genes increased substantially. In an immunohistochemical study, glucanase in LS-89 accumulated in the xylem and pith tissues surrounding xylem vessels filled with R. solanacearum. The expression of these genes also increased in four other resistant cultivars, but changed little in four susceptible cultivars in response to R. solanacearum, suggesting that similar reactions occur in other cultivars. These gene expression profiles will serve as fundamental information to elucidate the molecular mechanisms in the resistance response to R. solanacearum in tomato.


Via Biswapriya Biswavas Misra
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Pathogenomics of the Ralstonia solanacearum Species Complex - Annual Review of Phytopathology

Pathogenomics of the Ralstonia solanacearum Species Complex - Annual Review of Phytopathology | Ralstonia solanacearum of tomato | Scoop.it

Stéphane Genin and Timothy P. Denny

 

A great review to catch up with the genomic analysis of the Ralstonia solanacearum scpecies complex, pathogen evolution and the sofisticated network of regulators controlling pathogenesis.

It comes just in the right time, in my opinion. Both, as stated by the authors, to refine functional studies, but also to provide a refreshed and comprehensive state of the art in the field.

 

Abstract:

Ralstonia solanacearum is a major phytopathogen that attacks many crops and other plants over a broad geographical range. The extensive genetic diversity of strains responsible for the various bacterial wilt diseases has in recent years led to the concept of an R. solanacearum species complex. Genome sequencing of more than 10 strains representative of the main phylogenetic groups has broadened our knowledge of the evolution and speciation of this pathogen and led to the identification of novel virulence-associated functions. Comparative genomic analyses are now opening the way for refined functional studies. The many molecular determinants involved in pathogenicity and host-range specificity are described, and we also summarize current understanding of their roles in pathogenesis and how their expression is tightly controlled by an intricate virulence regulatory network.


Via Freddy Monteiro
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Freddy Monteiro's curator insight, February 24, 2013 11:15 AM

I hadn't notice this sentence before:

"Even though the known regulatory networks in R. solanacearum are already quite complex, you ain’t seen nothin’ yet!"

 

 

Amanzing!!

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Diagnosing Bacterial Wilt Diseases of Plants

This movie was made by Dr. Rob Wick, Plant Pathologist at UMass Amherst during a diagnostic plant pathology workshop in Bangladesh.
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