scholarly journals PsrA, the Pseudomonas Sigma Regulator, Controls Regulators of Epiphytic Fitness, Quorum-Sensing Signals, and Plant Interactions in Pseudomonas syringae pv. tomato Strain DC3000

2007 ◽  
Vol 73 (11) ◽  
pp. 3684-3694 ◽  
Author(s):  
Asita Chatterjee ◽  
Yaya Cui ◽  
Hiroaki Hasegawa ◽  
Arun K. Chatterjee
Keyword(s):  
Quorum Sensing ◽  
Pseudomonas Syringae ◽  
Stress Responses ◽  
Sigma Factor ◽  
Rna Binding ◽  
Negative Regulator ◽  
Insertion Mutant ◽  
Plant Interactions ◽  
Mobility Shift ◽  
Quorum Sensing Signals

ABSTRACT Pseudomonas syringae pv. tomato strain DC3000, a pathogen of tomato and Arabidopsis, occurs as an epiphyte. It produces N-acyl homoserine lactones (AHLs) which apparently function as quorum-sensing signals. A Tn5 insertion mutant of DC3000, designated PsrA− (Psr is for Pseudomonas sigma regulator), overexpresses psyR (a LuxR-type regulator of psyI) and psyI (the gene for AHL synthase), and it produces a ca. 8-fold-higher level of AHL than does DC3000. The mutant is impaired in its ability to elicit the hypersensitive reaction and is attenuated in its virulence in tomato. These phenotypes correlate with reduced expression of hrpL, the gene for an alternate sigma factor, as well as several hrp and hop genes during early stages of incubation in a Hrp-inducing medium. PsrA also positively controls rpoS, the gene for an alternate sigma factor known to control various stress responses. By contrast, PsrA negatively regulates rsmA1, an RNA-binding protein gene known to function as negative regulator, and aefR, a tetR-like gene known to control AHL production and epiphytic fitness in P. syringae pv. syringae. Gel mobility shift assays and other lines of evidence demonstrate a direct interaction of PsrA protein with rpoS promoter DNA and aefR operator DNA. In addition, PsrA negatively autoregulates and binds the psrA operator. In an AefR− mutant, the expression of psyR and psyI and AHL production are lower than those in DC3000, the AefR+ parent. In an RpoS− mutant, on the other hand, the levels of AHL and transcripts of psyR and psyI are much higher than those in the RpoS+ parent, DC3000. We present evidence, albeit indirect, that the RpoS effect occurs via psyR. Thus, AefR positively regulates AHL production, whereas RpoS has a strong negative effect. We show that AefR and RpoS do not regulate PsrA and that the PsrA effect on AHL production is exerted via its cumulative, but independent, effects on both AefR and RpoS.

scholarly journals A Role for Bradyrhizobium japonicum ECF16 Sigma Factor EcfS in the Formation of a Functional Symbiosis with Soybean

2012 ◽  
Vol 25 (1) ◽  
pp. 119-128 ◽  
Author(s):  
S. B. Stockwell ◽  
L. Reutimann ◽  
M. L. Guerinot
Keyword(s):  
Stress Responses ◽  
Sigma Factor ◽  
Bradyrhizobium Japonicum ◽  
Critical Role ◽  
Negative Regulator ◽  
In Planta ◽  
Cellular Processes ◽  
Core Enzyme ◽  
Σ Factor ◽  
Target Promoters

Alternative sigma (σ) factors, proteins that recruit RNA polymerase core enzyme to target promoters, are one mechanism by which bacteria transcriptionally regulate groups of genes in response to environmental stimuli. A class of σ70 proteins, termed extracytoplasmic function (ECF) σ factors, are involved in cellular processes such as bacterial stress responses and virulence. Here, we describe an ECF16 σ factor, EcfS (Blr4928) from the gram-negative soil bacterium Bradyrhizobium japonicum USDA110, that plays a critical role in the establishment of a functional symbiosis with soybean. Nonpolar insertional mutants of ecfS form immature nodules that do not fix nitrogen, a defect that can be successfully complemented by expression of ecfS. Overexpression of the cocistronic gene, tmrS (blr4929), phenocopies the ecfS mutant in planta and, therefore, we propose that TmrS is a negative regulator of EcfS, a determination consistent with the prediction that it encodes an anti-σ factor. Microarray analysis of the ecfS mutant and tmrS overexpressor was used to identify 40 transcripts misregulated in both strains. These transcripts primarily encode proteins of unknown and transport-related functions and may provide insights into the symbiotic defect in these strains.

scholarly journals The RsmA RNA-Binding Proteins in Pseudomonas syringae Exhibit Distinct and Overlapping Roles in Modulating Virulence and Survival Under Different Nutritional Conditions

2021 ◽  
Vol 12 ◽  
Author(s):  
Jun Liu ◽  
Menghao Yu ◽  
Yixin Ge ◽  
Yanli Tian ◽  
Baishi Hu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Stress Responses ◽  
Capsular Polysaccharide ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Expression Profiles ◽  
Transcriptomic Analysis ◽  
Phosphate Metabolism ◽  
Nutritional Conditions

The post-transcriptional regulator RsmA globally controls gene expression in bacteria. Previous studies showed that RsmA2 and RsmA3 played critical roles in regulating type III secretion system (T3SS), motility, syringafactin, and alginate productions in Pseudomonas syringae pv. tomato strain DC3000 (PstDC3000). In this study, we investigated global gene expression profiles of the wild-type PstDC3000, the rsmA3 mutant, and the rsmA2/A3 double mutant in the hrp-inducing minimum medium (HMM) and King’s B (KB) medium. By comparing the rsmA2/A3 and rsmA3 mutants to PstDC3000, a total of 1358 and 1074 differentially expressed genes (DEGs) in HMM, and 870 and 1463 DEGs in KB were uncovered, respectively. When comparing the rsmA2/A3 mutant with the rsmA3 mutant, 277 and 741 DEGs in HMM and KB, respectively, were revealed. Transcriptomic analysis revealed that the rsmY, rsmZ, and rsmX1-5 non-coding small RNAs (ncsRNAs) were positively affected by RsmA2 and RsmA3, while RsmA3 positively regulates the expression of the rsmA2 gene and negatively regulates both rsmA1 and rsmA5 gene expression. Comparative transcriptomic analysis showed that RsmA2 and RsmA3 synergistically influenced the expression of genes involved in T3SS and alginate biosynthesis in HMM and chemotaxis in KB. RsmA2 and RsmA3 inversely affected genes involved in syringafactin production in HMM and ribosomal protein biosynthesis in KB. In addition, RsmA2 played a major role in influencing genes involved in sarcosine and thiamine biosynthesis in HMM and in mannitol and phosphate metabolism in KB. On the other hand, genes involved in fatty acid metabolism, cellulose biosynthesis, signal transduction, and stress responses were mainly impacted by RsmA3 in both HMM and KB; whereas RsmA3 played a major role in controlling genes involved in c-di-GMP, phosphate metabolism, chemotaxis, and capsular polysaccharide in HMM. Furthermore, regulation of syringafactin production and oxidative stress by RsmA2 and RsmA3 was experimentally verified. Our results suggested the potential interplay among the RsmA proteins, which exhibit distinct and overlapping roles in modulating virulence and survival in P. syringae under different nutritional conditions.

scholarly journals A Soybean bZIP Transcription Factor GmbZIP19 Confers Multiple Biotic and Abiotic Stress Responses in Plant

2020 ◽  
Vol 21 (13) ◽  
pp. 4701
Author(s):  
Qing He ◽  
Hanyang Cai ◽  
Mengyan Bai ◽  
Man Zhang ◽  
Fangqian Chen ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Drought Stress ◽  
Pseudomonas Syringae ◽  
Stress Responses ◽  
Stomatal Closure ◽  
Negative Regulator ◽  
Marker Genes ◽  
Genes Expression ◽  
Salt And Drought Stress ◽  
Salt And Drought Stresses

The basic leucine zipper (bZIP) is a plant-specific transcription factor family that plays crucial roles in response to biotic and abiotic stresses. However, little is known about the function of bZIP genes in soybean. In this study, we isolated a bZIP gene, GmbZIP19, from soybean. A subcellular localization study of GmbZIP19 revealed its nucleus localization. We showed that GmbZIP19 expression was significantly induced by ABA (abscisic acid), JA (jasmonic acid) and SA (salicylic acid), but reduced under salt and drought stress conditions. Further, GmbZIP19 overexpression Arabidopsis lines showed increased resistance to S. sclerotiorum and Pseudomonas syringae associated with upregulated ABA-, JA-, ETH- (ethephon-)and SA-induced marker genes expression, but exhibited sensitivity to salt and drought stresses in association with destroyed stomatal closure and downregulated the salt and drought stresses marker genes’ expression. We generated a soybean transient GmbZIP19 overexpression line, performed a Chromatin immunoprecipitation assay and found that GmbZIP19 bound to promoters of ABA-, JA-, ETH-, and SA-induced marker genes in soybean. The yeast one-hybrid verified the combination. The current study suggested that GmbZIP19 is a positive regulator of pathogen resistance and a negative regulator of salt and drought stress tolerance.

scholarly journals RsmA and the Quorum-Sensing Signal, N-[3-Oxohexanoyl]- l-Homoserine Lactone, Control the Levels of rsmB RNA in Erwinia carotovora subsp. carotovora by Affecting Its Stability

2002 ◽  
Vol 184 (15) ◽  
pp. 4089-4095 ◽  
Author(s):  
Asita Chatterjee ◽  
Yaya Cui ◽  
Arun K. Chatterjee
Keyword(s):  
Quorum Sensing ◽  
Rna Binding ◽  
Critical Role ◽  
Regulatory System ◽  
Erwinia Carotovora ◽  
Homoserine Lactone ◽  
Negative Regulator ◽  
System Control ◽  
Transcriptional Fusion ◽  
Extracellular Protein Production

ABSTRACT RsmA (for regulator of secondary metabolism), RsmC, and rsmB RNA, the components of a posttranscriptional regulatory system, control extracellular protein production and pathogenicity in Erwinia carotovora subsp. carotovora. RsmA, an RNA binding protein, acts as a negative regulator by promoting message decay. rsmB RNA, on the other hand, acts as a positive regulator by neutralizing the effect of RsmA. RsmC modulates the levels of RsmA and rsmB RNA by positively regulating rsmA and negatively controlling rsmB. The level of rsmB RNA is substantially higher in RsmA+ bacteria than in RsmA− mutants. We show that rsmB RNA is more stable in the presence of RsmA than in its absence. RsmA does not stimulate the expression of an rsmB-lacZ transcriptional fusion; in fact, the β-galactosidase level is somewhat higher in RsmA− bacteria than in RsmA+ bacteria. We also investigated the basis for increased levels of rsmA and rsmB RNAs in the absence of the quorum-sensing signal, N-[3-oxohexanoyl]-l-homoserine lactone (OHL). The absence of OHL activates transcription of rsmA but not of rsmB. Instead, increased stability of rsmB RNA in the presence of RsmA accounts for the elevated levels of the rsmB RNA in OHL− bacteria. Mutant studies disclosed that while RsmA, OHL, and RsmC control the levels of rsmB RNA, high levels of rsmB RNA occur in the absence of RsmC or OHL only in RsmA+ bacteria, indicating a critical role for RsmA in modulating the levels of rsmB RNA. The findings reported here firmly establish that the quorum-sensing signal is channeled in E. carotovora subsp. carotovora via the rsmA-rsmB posttranscriptional regulatory system.

scholarly journals AlgU Controls Expression of Virulence Genes in Pseudomonas syringae pv. tomato DC3000

2016 ◽  
Vol 198 (17) ◽  
pp. 2330-2344 ◽  
Author(s):  
Eric Markel ◽  
Paul Stodghill ◽  
Zhongmeng Bao ◽  
Christopher R. Myers ◽  
Bryan Swingle
Keyword(s):  
Oxidative Stress ◽  
Pseudomonas Syringae ◽  
Stress Responses ◽  
Sigma Factor ◽  
Pathogenic Bacteria ◽  
Promoter Sequence ◽  
Tomato Dc3000 ◽  
Content Type ◽  
Plant Pathogenic Bacteria ◽  
And Oxidative Stress

ABSTRACTPlant-pathogenic bacteria are able to integrate information about their environment and adjust gene expression to provide adaptive functions. AlgU, an extracytoplasmic function (ECF) sigma factor encoded byPseudomonas syringae, controls expression of genes for alginate biosynthesis and genes involved with resisting osmotic and oxidative stress. AlgU is active while these bacteria are associated with plants, where its presence supports bacterial growth and disease symptoms. We found that AlgU is an important virulence factor forP. syringaepv. tomato DC3000 but that alginate production is dispensable for disease in host plants. This implies that AlgU regulates additional genes that facilitate bacterial pathogenesis. We used transcriptome sequencing (RNA-seq) to characterize the AlgU regulon and chromatin immunoprecipitation sequencing (ChIP-seq) to identify AlgU-regulated promoters associated with genes directly controlled by this sigma factor. We found that in addition to genes involved with alginate and osmotic and oxidative stress responses, AlgU regulates genes with known virulence functions, including components of the Hrp type III secretion system, virulence effectors, and thehrpLandhrpRStranscription regulators. These data suggest thatP. syringaepv. tomato DC3000 has adapted to use signals that activate AlgU to induce expression of important virulence functions that facilitate survival and disease in plants.IMPORTANCEPlant immune systems produce antimicrobial and bacteriostatic conditions in response to bacterial infection. Plant-pathogenic bacteria are adapted to suppress and/or tolerate these conditions; however, the mechanisms controlling these bacterial systems are largely uncharacterized. The work presented here provides a mechanistic explanation for howP. syringaepv. tomato DC3000 coordinates expression of multiple genetic systems, including those dedicated to pathogenicity, in response to environmental conditions. This work demonstrates the scope of AlgU regulation inP. syringaepv. tomato DC3000 and characterizes the promoter sequence regulated by AlgU in these bacteria.

scholarly journals A Rice Immunophilin Homolog, OsFKBP12, Is a Negative Regulator of Both Biotic and Abiotic Stress Responses

2020 ◽  
Vol 21 (22) ◽  
pp. 8791
Author(s):  
Ming-Yan Cheung ◽  
Wan-Kin Auyeung ◽  
Kwan-Pok Li ◽  
Hon-Ming Lam
Keyword(s):  
Abiotic Stress ◽  
Pseudomonas Syringae ◽  
Stress Responses ◽  
Biotic Stress ◽  
Higher Plants ◽  
Functional Characterization ◽  
Negative Regulator ◽  
Abiotic Stress Response ◽  
Biotic And Abiotic Stress ◽  
Higher Plant

A class of proteins that were discovered to bind the immunosuppressant drug FK506, called FK506-binding proteins (FKBPs), are members of a sub-family of immunophilins. Although they were first identified in human, FKBPs exist in all three domains of life. In this report, a rice FKBP12 homolog was first identified as a biotic stress-related gene through suppression subtractive hybridization screening. By ectopically expressing OsFKBP12 in the heterologous model plant system, Arabidopsis thaliana, for functional characterization, OsFKBP12 was found to increase susceptibility of the plant to the pathogen, Pseudomonas syringae pv. tomato DC3000 (Pst DC3000). This negative regulatory role of FKBP12 in biotic stress responses was also demonstrated in the AtFKBP12-knockout mutant, which exhibited higher resistance towards Pst DC3000. Furthermore, this higher-plant FKBP12 homolog was also shown to be a negative regulator of salt tolerance. Using yeast two-hybrid tests, an ancient unconventional G-protein, OsYchF1, was identified as an interacting partner of OsFKBP12. OsYchF1 was previously reported as a negative regulator of both biotic and abiotic stresses. Therefore, OsFKBP12 probably also plays negative regulatory roles at the convergence of biotic and abiotic stress response pathways in higher plants.

Quorum sensing in soft-rotting Erwinia carotovora

2005 ◽  
Author(s):  
◽  
Hiroaki Hasegawa
Keyword(s):  
Quorum Sensing ◽  
Rna Binding ◽  
Elevated Temperatures ◽  
Minor Component ◽  
Pectate Lyase ◽  
Erwinia Carotovora ◽  
Homoserine Lactone ◽  
Class Ii ◽  
Negative Regulator ◽  
Class I

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The soft-rotting E. carotovora subspecies (ssp.) produces effectors and an array ofextra cellular enzymes, including pectate lyase (Pel), polygalacturonase (Peh), cellulase (Cell) and protease (Prt) that are known or predicted to function as virulence and pathogenicity factors. The production of these exoproteins is activated by quorum sensing (QS)signal, N-acyl homoserine lactone (AHL). At elevated temperatures, however, a majority of E. c. ssp. atroseptica (Eca), betavasculorum (Ecb) and carotovora (Ecc) strains produce much reduced amounts of AHL as well as those exoproteins, and activate the production of a global negative regulator, RsmA (Rsm = regulator of secondarymetabolites). Ecc strain EC153 is an exception in that it produces higher levels of exproteins as well as AHL at 34.5[degree sign]C than at 28[degree sign]C. Temperature-dependent production of virrulence factors by these strains correlates with overall metabolic activities and stabilities of ahlI (the gene for AHL synthase), pel-1 and peh-1 transcripts. EC153 also causes extensive maceration of celery and Chinese cabbage petioles at 34.5[degree sign]C, which contrasts with limited tissue maceration by Ecc strain Ecc71 at this temperature. Thus, overall metabolic activity, higher levels of AHL and greater mRNA stability of virulence activates transcription of rsmA. This activation of rsmA is prevented by AHL. Consequently, in the presence of AHL RsmA production occurs at a low level, triggering the production of virulence factors. These findings for the first time document regulation of an RNA-binding protien by ExpR and AHL, link quorum sensing system via posttransciptional regulation, and explain the basis for the pleiotropic effects of AHL in Ecc. This study also reports the existence of two classes of strains based on structural and functional characteristics of ExpR and AhlI in Erwinia carotovora subspecies. While class I strains produce 3-oxooctanoyl-L-homoserine lactone (3-oxo-C8-HL) as the major AHL analog and 3-oxohexanoyl homoserine lactone (3-oxo-C6-HL) as a minor component, the members of class II strains produce 3-oxo-C6-HL as the major analog. It has also been found that AHL synthase is responsible for biosynthetic specificity. ExpR species do not discriminate between rsmA genes of strains belonging to the two classes. However, specificity is conferred by AHL analogs in that 3-oxo-C8-HL neutralizes the actions of class II ExpRs whereas 3-oxo-C6HL neutalizes class I ExpRs.

scholarly journals Wounding-Induced WRKY8 Is Involved in Basal Defense in Arabidopsis

2010 ◽  
Vol 23 (5) ◽  
pp. 558-565 ◽  
Author(s):  
Ligang Chen ◽  
Liping Zhang ◽  
Diqiu Yu
Keyword(s):  
Transgenic Plants ◽  
Pseudomonas Syringae ◽  
Stress Responses ◽  
Plant Stress ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Basal Resistance ◽  
Plant Stress Responses ◽  
Dna Insertion ◽  
Insertion Mutants

The WRKY family of plant transcription factors controls several types of plant stress responses. Arabidopsis WRKY8, localized to the nucleus, is mainly induced by abscissic acid, H2O2, wounding, Pseudomonas syringae and Botrytis cinerea infection, and aphid and maggot feeding. To determine its biological functions, we isolated loss-of-function T-DNA insertion mutants and generated gain-of-function overexpressing WRKY8 transgenic plants in Arabidopsis. Plants expressing the mutated WRKY8 gene showed increased resistance to P. syringae but slightly decreased resistance to B. cinerea. In contrast, transgenic plants overexpressing WRKY8 were more susceptible to P. syringae infection but more resistant to B. cinerea infection. The contrasting responses to the two pathogens were correlated with opposite effects on pathogen-induced expression of two genes; salicylic acid-regulated PATHOGENESIS-RELATED1 (PR1) and jasmonic acid-regulated PDF1.2. Therefore, our results suggest that WRKY8 is a negative regulator of basal resistance to P. syringae and positive regulator to B. cinerea.

scholarly journals The Arabidopsis homolog of human G3BP1 is a key regulator of stomatal and apoplastic immunity

2018 ◽  
Vol 1 (2) ◽  
pp. e201800046 ◽  
Author(s):  
Aala A Abulfaraj ◽  
Kiruthiga Mariappan ◽  
Jean Bigeard ◽  
Prabhu Manickam ◽  
Ikram Blilou ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Plant Immunity ◽  
Bacterial Pathogen ◽  
Defense Responses ◽  
Pathogen Resistance ◽  
Negative Regulator ◽  
Multifunctional Protein

Mammalian Ras-GTPase–activating protein SH3-domain–binding proteins (G3BPs) are a highly conserved family of RNA-binding proteins that link kinase receptor-mediated signaling to RNA metabolism. Mammalian G3BP1 is a multifunctional protein that functions in viral immunity. Here, we show that the Arabidopsis thaliana homolog of human G3BP1 negatively regulates plant immunity. Arabidopsis g3bp1 mutants showed enhanced resistance to the virulent bacterial pathogen Pseudomonas syringae pv. tomato. Pathogen resistance was mediated in Atg3bp1 mutants by altered stomatal and apoplastic immunity. Atg3bp1 mutants restricted pathogen entry into stomates showing insensitivity to bacterial coronatine–mediated stomatal reopening. AtG3BP1 was identified as a negative regulator of defense responses, which correlated with moderate up-regulation of salicylic acid biosynthesis and signaling without growth penalty.

scholarly journals Analysis of Seaweed Extract-induced Transcriptome Leads to Identification of a Negative Regulator of Salt Tolerance in Arabidopsis

HortScience ◽  
2012 ◽  
Vol 47 (6) ◽  
pp. 704-709 ◽  
Author(s):  
Mundaya N. Jithesh ◽  
Owen S.D. Wally ◽  
Iain Manfield ◽  
Alan T. Critchley ◽  
David Hiltz ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Salinity Stress ◽  
Stress Responses ◽  
Molecular Mechanisms ◽  
Primary Root ◽  
Brown Seaweed ◽  
Nacl Stress ◽  
Negative Regulator ◽  
Insertion Mutant ◽  
Dna Insertion

Successful development of plants resistant to salinity stress is problematic as a result of the complex polygenic natures of salt tolerance. Previously, alkaline extracts of the brown seaweed Ascophyllum nodosum have shown promise in enhancing plant tolerance toward abiotic stresses. To understand the underlying molecular mechanisms, the whole genome transcriptome of Arabidopsis undergoing salt stress was analyzed by microarray analysis after treatment with the chemical components of A. nodosum extracts (ANE). Treatment with ANE induced many positive regulators of salt tolerance in addition to downregulating numerous other genes. Using T-DNA insertion mutants within these downregulated genes, we examined the potential for a novel source of enhanced NaCl tolerance through removal of negative regulators of NaCl stress responses within Arabidopsis. Several potential target mutations were identified with enhanced salt-tolerant phenotypes. A T-DNA insertion within the promoter of a putative Pectin Methyl Esterase Inhibitor (PMEI) gene (At1g62760) was found to be resistant to salinity stress and was further characterized. This T-DNA insertion mutant was designated as pmei1-1. The phenotype of pmei1-1 seedlings included increased primary root growth in vitro and improved biomass accumulation under NaCl stress. Additionally, modified transcript levels of dehydration-responsive genes, including RD29A, were observed in pmei1-1 plants. Taken together, these results suggest a role for PMEI as a negative regulator of NaCl resistance and that chemical stress-induced transcriptome analysis may lead to identification of additional novel regulators of abiotic stress tolerance in plants, the use of which would have significant implications for agriculture globally.

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