Isolation and Characterization of a<i>Pseudomonas syringae</i>pv.<i>syringae</i>Mutant Deficient in Lesion Formation on Bean

Willis, David K.; Hrabak, Estelle M.; Rich, J J; Barta, T. M.; Lindow, Steven E.; Panopoulos, Nickolas J.

doi:10.1094/mpmi-3-149

Cited by 93 publications

(70 citation statements)

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“…Previously, we had identified six distinct cosmids from a wild-type genomic library of P. syringae pv. syringae isolate B728a that were able to complement a lemAJ41::Tn5 mutant (55). These cosmids overlapped each other in a common region of approximately 7 kb that, we assumed, contained the functional lemA locus.…”

Section: Resultsmentioning

confidence: 99%

“…To identify bacterial genes necessary for disease development, prototrophic Tn5 mutants of isolate B728a were screened on bean pods for loss of the typical pathogenic response. One mutant, NPS3136, has lost the ability to form brown spot lesions on bean leaves and pods (55). This lemA (lesion manifestation) mutant retains the ability to grow on and colonize bean plants and to elicit a hypersensitive reaction on nonhosts (55).…”

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“…One mutant, NPS3136, has lost the ability to form brown spot lesions on bean leaves and pods (55). This lemA (lesion manifestation) mutant retains the ability to grow on and colonize bean plants and to elicit a hypersensitive reaction on nonhosts (55). The phenotype of a lemA mutant is significantly different from the phenotype of another class of nonpathogenic mutants, the hrp mutants, which are affected both in their colonization of and pathogenic interaction with host plants and in their ability to elicit a hypersensitive reaction on nonhost plants (for a review, see reference 56).…”

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The lemA gene required for pathogenicity of Pseudomonas syringae pv. syringae on bean is a member of a family of two-component regulators

1992

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The lemA gene of the plant pathogen Pseudomonas syringae pv. syringae is required for disease lesion formation on bean plants. Cosmid clones that complemented a lemA mutant in trans were isolated previously. The lemA gene was localized by subcloning and transposon mutagenesis. The lemA region and flanking DNA were sequenced, and an open reading frame of 2.7 kb was identified. The nucleotide and predicted amino acid sequences of the kmA gene showed sequence similarity to a family of prokaryotic two-component regulatory proteins. Unlike most of the previously described two-component systems, the lemA gene product contained homology to both components in one protein. Pseudomonas syringae pv. syringae isolate B728a is a causal agent of bacterial brown spot of bean (Phaseolus vulgaris). To identify bacterial genes necessary for disease development, prototrophic Tn5 mutants of isolate B728a were screened on bean pods for loss of the typical pathogenic response. One mutant, NPS3136, has lost the ability to form brown spot lesions on bean leaves and pods (55). This lemA (lesion manifestation) mutant retains the ability to grow on and colonize bean plants and to elicit a hypersensitive reaction on nonhosts (55). The phenotype of a lemA mutant is significantly different from the phenotype of another class of nonpathogenic mutants, the hrp mutants, which are affected both in their colonization of and pathogenic interaction with host plants and in their ability to elicit a hypersensitive reaction on nonhost plants (for a review, see reference 56). Further characterization of the lemA mutant revealed that it was also deficient in the ability to produce protease and the toxin syringomycin (19,20). This pleiotropic phenotype suggested that the lemA gene might encode a regulatory molecule. In this report, we describe further characterization of the lemA gene of P. syringae pv. syringae by subcloning, transposon mutagenesis, and DNA sequence analysis. We present evidence that the lemA gene has similarity to the conserved domains within both the HPK and the RR proteins in a family of prokaryotic two-component regulatory proteins. MATERIALS AND METHODSBacterial strains, plasmids, and growth conditions. The bacterial strains and plasmids used in this work are listed in

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Section: Resultsmentioning

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The lemA gene required for pathogenicity of Pseudomonas syringae pv. syringae on bean is a member of a family of two-component regulators

1992

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“…Most of the remaining genes in the hrp cluster encode structural proteins that are involved in the synthesis or export of pathogenicity factors (78). As mentioned above, the nine hrc genes are homologous to members of the Yersinia type III secretory pathway that is responsible for translocating Yop proteins into host cells (18,24,53,73).…”

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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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“…In addition, a sylC insertional knock-out mutant was constructed in strain B728a. B301D-R was isolated from a diseased pear fruit (Xu and Gross, 1988) and B728a from bean (Willis et al, 1990). Preliminary results of assays of syringolin-negative mutants and the wild-type strain indicate that the mutant causes less disease symptoms than the wild type, suggesting that syringolin A indeed is a virulence factor.…”

Section: Resultsmentioning

confidence: 99%

Syringolin A: Action on Plants, Regulation of Biosynthesis and Phylogenetic Occurrence of Structurally Related Compounds

Schellenberg

Ramel

Dudler

2008

Pseudomonas Syringae Pathovars and Related Pathogens – Identification, Epidemiology and Genomics

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Cloning of the syringolin A synthetase genes has allowed us to build a detailed model of syringolin A synthesis based on the gene structure. This model in turn enabled us to clone the genes responsible for the synthesis of glidobactins (syn. cepafungins), antibiotics with a structure related to syringolin A that were reported to have antitumor activity, from an unknown species belonging to the order Burkholderiales. Comparisons to the approximately 700 complete eubacterial genomic sequences known resulted in the identification of a small but very intriguing group of pathogenic bacteria postulated to produce glidobacting-like molecules.

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Isolation and Characterization of aPseudomonas syringaepv.syringaeMutant Deficient in Lesion Formation on Bean

Cited by 93 publications

References 0 publications

The lemA gene required for pathogenicity of Pseudomonas syringae pv. syringae on bean is a member of a family of two-component regulators

The lemA gene required for pathogenicity of Pseudomonas syringae pv. syringae on bean is a member of a family of two-component regulators

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

Syringolin A: Action on Plants, Regulation of Biosynthesis and Phylogenetic Occurrence of Structurally Related Compounds

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