Reduced pathogen fitness of Pseudomonas syringae pv. tomato Tn5 mutants defective in coronatine production

Bender, Carol L.; Stone, Hannah; Sims, James J.; Cooksey, Donald A.

doi:10.1016/0885-5765(87)90040-3

Cited by 140 publications

(87 citation statements)

References 17 publications

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“…We show in the accompanying study that the phytotoxin coronatine is one such factor, being absent in rpoN mutants and not restored by constitutive hrpL expression (32). Coronatine is a non-host-specific toxin that primarily elicits chlorosis but is also known to induce hypertrophy and inhibit root elongation (7,19,69). Studies of coronatine-defective mutants of P. syringae pv.…”

Section: Discussionmentioning

confidence: 78%

The Alternative Sigma Factor RpoN Is Required for hrp Activity in Pseudomonas syringae pv. Maculicola and Acts at the Level of hrpL Transcription

2000

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␤-Glucuronidase (uidA) reporter gene fusions were constructed for the hrpZ, hrpL, and hrpS genes from the phytopathogen Pseudomonas syringae pv. maculicola strain ES4326. These reporters, as well as an avrRpt2-uidA fusion, were used to measure transcriptional activity in ES4326 and a ES4326 rpoN mutant. rpoN was required for the expression of avrRpt2, hrpZ, and hrpL in vitro in minimal media and in vivo when infiltrated into Arabidopsis thaliana leaves. In contrast, the expression of hrpS was essentially the same in wild-type and rpoN mutant strains. Constitutive expression of hrpL in an rpoN mutant restored hrpZ transcription to wild-type levels, restored the hypersensitive response when infiltrated into tobacco (Nicotiana tobacum), and partially restored the elicitation of virulence-related symptoms but not growth when infiltrated into Arabidopsis leaves. These data indicate that rpoN-mediated control of hrp gene expression acts at the level of hrpL and that in planta growth of P. syringae is not required for the elicitation of disease symptoms.In gram-negative bacteria, transcriptional activation in response to external stimuli often involves the alternative sigma factor 54 (1, 50). 54 , which is encoded by rpoN, works in conjunction with members of the NtrC superfamily of transcriptional activators (1, 50). Among the different enzymatic pathways under 54 control are those responsible for nitrogen utilization, dicarboxylate transport, xylene degradation, and hydrogen utilization (8,39,47,79).In the case of some phytopathogenic bacterial species, rpoN has been implicated indirectly as a regulator of a large cluster of pathogenicity-related genes known as the hrp gene cluster (17,27). For example, Pseudomonas syringae pv. syringae strain 61 contains a 25-kb hrp cluster consisting of 27 genes arranged as follows : hrpKL, hrpJ, hrcV, hrpQ, hrcN, hrpOP, hrcQRSTU, hrpVT, hrcC, hrpGF, hrpED, hrcJ, hrpBZA, and hrpSR (11,33). The acronym hrp stands for hypersensitive response and pathogenicity. The genes within the hrp cluster are required not only for pathogenicity but also for elicitation of the plant resistance reaction known as the hypersensitive response (HR) (44, 45). The HR involves rapid, localized plant cell death, which is triggered by a gene-for-gene interaction between a particular avirulence (avr) gene in the pathogen and a corresponding resistance gene in the host (21, 56). The widely conserved members of the hrp cluster, designated hrc, show significant homology to members of the Yersinia type III secretory pathway and in the new simplified nomenclature bear the letter designation of the corresponding Yersinia gene (9). (The exception is hrcV, which is homologous to the Yersinia lcrD genes.)Sequence analysis of the hrp cluster in P. syringae pv. phaseolicola suggested that 54 would be required for hrp gene expression in conjunction with the hrpRS genes, which are required for expression of the remaining hrp genes in the cluster (17, 27). hrpR and hrpS encode proteins that contain the domain conserved ...

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Section: Discussionmentioning

confidence: 78%

The Alternative Sigma Factor RpoN Is Required for hrp Activity in Pseudomonas syringae pv. Maculicola and Acts at the Level of hrpL Transcription

2000

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“…Although other genes can contribute to the success of infections, growth and virulence within the plant host is primarily determined by a type III secretion system that delivers strain-specific suites of ''type III effectors'' into eukaryotic host cells (He et al 2004) and, in many strains, provides the regulation for production of specific toxins (Bender et al 1987) that can mimic plant hormones (Katsir et al 2008). Type III effector proteins are virulence factors and can directly disrupt plant immune function and signaling within host tissues, allowing the extracellular bacteria to survive, multiply, and disperse (Mudgett 2005;Grant et al 2006).…”

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confidence: 99%

De novo assembly using low-coverage short read sequence data from the rice pathogen Pseudomonas syringae pv. oryzae

Reinhardt¹,

Baltrus²,

Nishimura³

et al. 2008

Genome Res.

132

109

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We developed a novel approach for de novo genome assembly using only sequence data from high-throughput short read sequencing technologies. By combining data generated from 454 Life Sciences (Roche) and Illumina (formerly known as Solexa sequencing) sequencing platforms, we reliably assembled genomes into large scaffolds at a fraction of the traditional cost and without use of a reference sequence. We applied this method to two isolates of the phytopathogenic bacteria Pseudomonas syringae. Sequencing and reassembly of the well-studied tomato and Arabidopsis pathogen, Pto DC3000 , facilitated development and testing of our method. Sequencing of a distantly related rice pathogen, Por 1_6 , demonstrated our method's efficacy for de novo assembly of novel genomes. Our assembly of Por 1_6 yielded an N50 scaffold size of 531,821 bp with >75% of the predicted genome covered by scaffolds over 100,000 bp. One of the critical phenotypic differences between strains of P. syringae is the range of plant hosts they infect. This is largely determined by their complement of type III effector proteins. The genome of Por 1_6 is the first sequenced for a P. syringae isolate that is a pathogen of monocots, and, as might be predicted, its complement of type III effectors differs substantially from the previously sequenced isolates of this species. The genome of Por 1_6 helps to define an expansion of the P. syringae pangenome, a corresponding contraction of the core genome, and a further diversification of the type III effector complement for this important plant pathogen species.

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“…In nine of the chlorosis-defective mutants, the coronatine-defective (Cor-) phenotype has been confirmed by fractionation of organic acids by either high-pressure liquid chromatography (3) or gas chromatography (GC) (18). The coronatine fraction, which has a distinctive retention time by either method, was absent from organic acids extracted from these nine mutants.…”

mentioning

confidence: 98%

“…glycinea (21), P. syringae pv. tomato (3,20), and P. syringae pv. morsprunorum (17), which are pathogens of ryegrass, soybean, tomato, and Prunus spp., respectively.…”

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confidence: 99%

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Plasmid-mediated production of the phytotoxin coronatine by Pseudomonas syringae pv. tomato

1989

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Pseudomonas syringae pv. tomato PT23.2 produces the chlorosis-inducing phytotoxin coronatine. Thirtyeight chlorosis-defective mutants of PT23.2 were previously generated by using the transposon TnS. Five mutants contained Tn5 insertions in the indigenous plasmid pPT23A; the remaining 33 mutants either were missing pPT23A (29 mutants) or contained deletions in this plasmid (4 mutants). These results suggested that pPT23A was involved in coronatine production in strain PT23.2. This plasmid was introduced into P. syringae pv. syringae PS61, which does not produce coronatine. A bioassay for coronatine suggested that PS61(pPT23A) transconjugants were able to make this phytotoxin. In a chemical analysis, organic acids were isolated from PT23.2, PS61, and the transconjugant PS61(pPT23A); these were derivatized to their methyl esters and analyzed by gas chromatography. The derivatized organic acids extracted from PT23.2 and PS61(pPT23A) contained peaks that corresponded to coronafacic acid, coronafacoylvaline, and coronatine, but these were absent in the extracts from the wild-type strain PS61. The identification of these components was confirmed by combined gas chromatography-mass spectrophotometry. Therefore, the acquisition of pPT23A by PS61 resulted in biosynthesis of coronafacic acid, coronafacoylvaline, and coronatine, clearly demonstrating the involvement of pPT23A in coronatine production in P. syringae pv. tomato.The chlorosis-inducing phytotoxin coronatine has a unique structure (Fig. 1), consisting of a polyketide component (coronafacic acid) joined to a cyclopropane structure derived from isoleucine (11,19,24). Coronatine is produced by several Pseudomonas syringae pathovars, including P. syringae pv. atropurpurea (23), P. syringae pv. glycinea (21), P. syringae pv. tomato (3, 20), and P. syringae pv. morsprunorum (17), which are pathogens of ryegrass, soybean, tomato, and Prunus spp., respectively. Coronatine production by multiple pathovars of P. syringae contrasts with production of the phytotoxins phaseolotoxin and syringomycin, which is thought to be restricted to P. syringae pv. phaseolicola and P. syringae pv. syringae, respectively. In addition to chlorosis, coronatine induces stunting (8) and hypertrophy (28) of plant tissue. Recently, Bender et al. (3) reported that coronatine synthesis is important in the virulence of P. syringae pv. tomato and contributes significantly to both lesion expansion and multiplication of the bacterium in tomato leaves. The unusual structure and biosynthetic origin of coronatine and its importance in the symptomology of several P. syringae pathovars have prompted us to study the genetics of its production.In a previous study (3), 1,000 Tn5 mutants of strain PT23.2 were generated and screened for their ability to induce chlorosis in planta. Ten chlorosis-defective, nontoxigenic (Tox-) mutants were recovered; nine mutants were further analyzed and found to be defective in production of coronatine (3; R. E. Mitchell, personal communication). In the present study, the phy...

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Reduced pathogen fitness of Pseudomonas syringae pv. tomato Tn5 mutants defective in coronatine production

Cited by 140 publications

References 17 publications

The Alternative Sigma Factor RpoN Is Required for hrp Activity in Pseudomonas syringae pv. Maculicola and Acts at the Level of hrpL Transcription

The Alternative Sigma Factor RpoN Is Required for hrp Activity in Pseudomonas syringae pv. Maculicola and Acts at the Level of hrpL Transcription

De novo assembly using low-coverage short read sequence data from the rice pathogen Pseudomonas syringae pv. oryzae

Plasmid-mediated production of the phytotoxin coronatine by Pseudomonas syringae pv. tomato

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