scholarly journals Isolation, Characterization, and Pathogenicity of Two Pseudomonas syringae Pathovars from Populus trichocarpa Seeds

2020 ◽  
Vol 8 (8) ◽  
pp. 1137 ◽  
Author(s):  
Patricia MB Saint-Vincent ◽  
Mary Ridout ◽  
Nancy L. Engle ◽  
Travis J. Lawrence ◽  
Meredith L. Yeary ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Virulence Factors ◽  
Host Response ◽  
Plant Pathogens ◽  
Populus Trichocarpa ◽  
Bacterial Pathogen ◽  
Effector Proteins ◽  
Agricultural Crop ◽  
Pseudomonas Syringae Pathovars ◽  
Woody Host

Pseudomonas syringae is a ubiquitous plant pathogen, infecting both woody and herbaceous plants and resulting in devastating agricultural crop losses. Characterized by a remarkable specificity for plant hosts, P. syringae pathovars utilize a number of virulence factors including the type III secretion system and effector proteins to elicit disease in a particular host species. Here, two Pseudomonas syringae strains were isolated from diseased Populustrichocarpa seeds. The pathovars were capable of inhibiting poplar seed germination and were selective for the Populus genus. Sequencing of the newly described organisms revealed similarity to phylogroup II pathogens and genomic regions associated with woody host-associated plant pathogens, as well as genes for specific virulence factors. The host response to infection, as revealed through metabolomics, is the induction of the stress response through the accumulation of higher-order salicylates. Combined with necrosis on leaf surfaces, the plant appears to quickly respond by isolating infected tissues and mounting an anti-inflammatory defense. This study improves our understanding of the initial host response to epiphytic pathogens in Populus and provides a new model system for studying the effects of a bacterial pathogen on a woody host plant in which both organisms are fully genetically sequenced.

scholarly journals In planta bacterial multi-omics analysis illuminates regulatory principles underlying plant-pathogen interactions

2019 ◽  
Author(s):  
Tatsuya Nobori ◽  
Yiming Wang ◽  
Jingni Wu ◽  
Sara Christina Stolze ◽  
Yayoi Tsuda ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Pseudomonas Syringae ◽  
Protein Level ◽  
Plant Pathogens ◽  
Plant Immunity ◽  
Bacterial Pathogen ◽  
Bacterial Virulence ◽  
In Planta ◽  
Bacterial Gene ◽  
Global Food Security

AbstractUnderstanding how gene expression is regulated in plant pathogens is crucial for pest control and thus global food security. An integrated understanding of bacterial gene regulation in the host is dependent on multi-omic datasets, but these are largely lacking. Here, we simultaneously characterized the transcriptome and proteome of a foliar bacterial pathogen, Pseudomonas syringae, in Arabidopsis thaliana and identified a number of bacterial processes influenced by plant immunity at the mRNA and the protein level. We found instances of both concordant and discordant regulation of bacterial mRNAs and proteins. Notably, the tip component of bacterial type III secretion system was selectively suppressed by the plant salicylic acid pathway at the protein level, suggesting protein-level targeting of the bacterial virulence system by plant immunity. Furthermore, gene co-expression analysis illuminated previously unknown gene regulatory modules underlying bacterial virulence and their regulatory hierarchy. Collectively, the integrated in planta bacterial omics approach provides molecular insights into multiple layers of bacterial gene regulation that contribute to bacterial growth in planta and elucidate the role of plant immunity in controlling pathogens.

scholarly journals Armet, an aphid effector protein, induces pathogen resistance in plants by promoting the accumulation of salicylic acid

2019 ◽  
Vol 374 (1767) ◽  
pp. 20180314 ◽  
Author(s):  
Na Cui ◽  
Hong Lu ◽  
Tianzuo Wang ◽  
Wenhao Zhang ◽  
Le Kang ◽  
...  
Keyword(s):  
Salicylic Acid ◽  
Pseudomonas Syringae ◽  
Plant Pathogen ◽  
Bacterial Pathogen ◽  
Pathogen Resistance ◽  
Effector Proteins ◽  
Mitogen Activated Protein Kinase ◽  
Effector Protein ◽  
Plant Interactions ◽  
Fourfold Increase

Effector proteins present in aphid saliva are thought to modulate aphid–plant interactions. Armet, an effector protein, is found in the phloem sap of pea-aphid-infested plants and is indispensable for the survival of aphids on plants. However, its function in plants has not been investigated. Here, we explored the functions of Armet after delivery into plants. Examination of the transcriptomes of Nicotiana benthamiana and Medicago truncatula following transgenic expression of Armet or infiltration of the protein showed that Armet activated pathways associated with plant–pathogen interactions, mitogen-activated protein kinase and salicylic acid (SA). Armet induced a fourfold increase in SA accumulation by regulating the expression of SAMT and SABP2 , two genes associated with SA metabolism, in Armet-infiltrated tobacco. The increase in SA enhanced the plants' resistance to bacterial pathogen Pseudomonas syringae but had no detectable adverse effects on aphid survival or reproduction. Similar molecular responses and a chlorosis phenotype were induced in tobacco by Armet from two aphid species but not by locust Armet, suggesting that the effector function of Armet may be specific for aphids. The results suggest that Armet causes plants to make a pathogen-resistance decision and reflect a novel tripartite insect–plant–pathogen interaction. This article is part of the theme issue ‘Biotic signalling sheds light on smart pest management’.

scholarly journals Functional Characterization of Key Residues in Regulatory Proteins HrpG and HrpV of Pseudomonas syringae pv. tomato DC3000

2017 ◽  
Vol 30 (8) ◽  
pp. 656-665 ◽  
Author(s):  
Milija Jovanovic ◽  
Christopher Waite ◽  
Ellen James ◽  
Nicholas Synn ◽  
Timothy Simpson ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Pathogens ◽  
Functional Characterization ◽  
Direct Interaction ◽  
Negative Control ◽  
Effector Proteins ◽  
Tomato Dc3000 ◽  
Sequence Alignments ◽  
Group I ◽  
Σ Factor

The plant pathogen Pseudomonas syringae pv. tomato DC3000 uses a type III secretion system (T3SS) to transfer effector proteins into the host. The expression of T3SS proteins is controlled by the HrpL σ factor. Transcription of hrpL is σ54-dependent and bacterial enhancer-binding proteins HrpR and HrpS coactivate the hrpL promoter. The HrpV protein imposes negative control upon HrpR and HrpS through direct interaction with HrpS. HrpG interacts with HrpV and relieves such negative control. The sequence alignments across Hrp group I-type plant pathogens revealed conserved HrpV and HrpG amino acids. To establish structure–function relationships in HrpV and HrpG, either truncated or alanine substitution mutants were constructed. Key functional residues in HrpV and HrpG are found within their C-terminal regions. In HrpG, L101 and L105 are indispensable for the ability of HrpG to directly interact with HrpV and suppress HrpV-dependent negative regulation of HrpR and HrpS. In HrpV, L108 and G110 are major determinants for interactions with HrpS and HrpG. We propose that mutually exclusive binding of HrpS and HrpG to the same binding site of HrpV governs a transition from negative control to activation of the HrpRS complex leading to HrpL expression and pathogenicity of P. syringae.

scholarly journals Transcriptome landscape of a bacterial pathogen under plant immunity

2018 ◽  
Vol 115 (13) ◽  
pp. E3055-E3064 ◽  
Author(s):  
Tatsuya Nobori ◽  
André C. Velásquez ◽  
Jingni Wu ◽  
Brian H. Kvitko ◽  
James M. Kremer ◽  
...  
Keyword(s):  
Immune Response ◽  
Pseudomonas Syringae ◽  
Bacterial Growth ◽  
Plant Pathogens ◽  
Plant Immunity ◽  
Expression Patterns ◽  
Bacterial Pathogen ◽  
In Planta ◽  
Bacterial Strains ◽  
Bacterial Genes

Plant pathogens can cause serious diseases that impact global agriculture. The plant innate immunity, when fully activated, can halt pathogen growth in plants. Despite extensive studies into the molecular and genetic bases of plant immunity against pathogens, the influence of plant immunity in global pathogen metabolism to restrict pathogen growth is poorly understood. Here, we developed RNA sequencing pipelines for analyzing bacterial transcriptomes in planta and determined high-resolution transcriptome patterns of the foliar bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana with a total of 27 combinations of plant immunity mutants and bacterial strains. Bacterial transcriptomes were analyzed at 6 h post infection to capture early effects of plant immunity on bacterial processes and to avoid secondary effects caused by different bacterial population densities in planta. We identified specific “immune-responsive” bacterial genes and processes, including those that are activated in susceptible plants and suppressed by plant immune activation. Expression patterns of immune-responsive bacterial genes at the early time point were tightly linked to later bacterial growth levels in different host genotypes. Moreover, we found that a bacterial iron acquisition pathway is commonly suppressed by multiple plant immune-signaling pathways. Overexpression of a P. syringae sigma factor gene involved in iron regulation and other processes partially countered bacterial growth restriction during the plant immune response triggered by AvrRpt2. Collectively, this study defines the effects of plant immunity on the transcriptome of a bacterial pathogen and sheds light on the enigmatic mechanisms of bacterial growth inhibition during the plant immune response.

scholarly journals Roq1 confers resistance to Xanthomonas, Pseudomonas syringae and Ralstonia solanacearum in tomato

2019 ◽  
Author(s):  
Nicholas C. Thomas ◽  
Connor G. Hendrich ◽  
Upinder S. Gill ◽  
Caitilyn Allen ◽  
Samuel F. Hutton ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Ralstonia Solanacearum ◽  
Plant Pathogens ◽  
Field Trials ◽  
Current Control ◽  
Effector Proteins ◽  
Effective Control ◽  
Crop Species ◽  
Xanthomonas Perforans ◽  
Pathogen Effector

AbstractXanthomonas species, Pseudomonas syringae and Ralstonia solanacearum are bacterial plant pathogens that cause significant yield loss in many crop species. Current control methods for these pathogens are insufficient but there is significant potential for generating new disease-resistant crop varieties. Plant immune receptors encoded by nucleotide-binding, leucine-rich repeat (NLR) genes typically confer resistance to pathogens that produce a cognate elicitor, often an effector protein secreted by the pathogen to promote virulence. The diverse sequence and presence / absence variation of pathogen effector proteins within and between pathogen species usually limits the utility of a single NLR gene to protecting a plant from a single pathogen species or particular strains. The NLR protein Recognition of XopQ 1 (Roq1) was recently identified from the plant Nicotiana benthamiana and mediates perception of the effector proteins XopQ and HopQ1 from Xanthomonas and P. syringae respectively. Unlike most recognized effectors, alleles of XopQ/HopQ1 are highly conserved and present in most plant pathogenic strains of Xanthomonas and P. syringae. A homolog of XopQ/HopQ1, named RipB, is present in many R. solanacearum strains. We found that Roq1 also mediates perception of RipB and confers immunity to Xanthomonas, P. syringae, and R. solanacearum when expressed in tomato. Strong resistance to Xanthomonas perforans was observed in three seasons of field trials with both natural and artificial inoculation. The Roq1 gene can therefore be used to provide safe, economical and effective control of these pathogens in tomato and other crop species and reduce or eliminate the need for traditional chemical controls.SummaryA single immune receptor expressed in tomato confers strong resistance to three different bacterial diseases.

scholarly journals Identification of a Twin-Arginine Translocation System in Pseudomonas syringae pv. tomato DC3000 and Its Contribution to Pathogenicity and Fitness

2005 ◽  
Vol 187 (24) ◽  
pp. 8450-8461 ◽  
Author(s):  
Philip A. Bronstein ◽  
Matthew Marrichi ◽  
Sam Cartinhour ◽  
David J. Schneider ◽  
Matthew P. DeLisa
Keyword(s):  
Pseudomonas Syringae ◽  
Virulence Factors ◽  
Fluorescent Protein ◽  
Effector Proteins ◽  
Broad Host Range ◽  
Tomato Dc3000 ◽  
Phytopathogenic Bacterium ◽  
Type Iii ◽  
Twin Arginine Translocation ◽  
Tat System

ABSTRACT The bacterial plant pathogen Pseudomonas syringae pv. tomato DC3000 (DC3000) causes disease in Arabidopsis thaliana and tomato plants, and it elicits the hypersensitive response in nonhost plants such as Nicotiana tabacum and Nicotiana benthamiana. While these events chiefly depend upon the type III protein secretion system and the effector proteins that this system translocates into plant cells, additional factors have been shown to contribute to DC3000 virulence and still many others are likely to exist. Therefore, we explored the contribution of the twin-arginine translocation (Tat) system to the physiology of DC3000. We found that a tatC mutant strain of DC3000 displayed a number of phenotypes, including loss of motility on soft agar plates, deficiency in siderophore synthesis and iron acquisition, sensitivity to copper, loss of extracellular phospholipase activity, and attenuated virulence in host plant leaves. In the latter case, we provide evidence that decreased virulence of tatC mutants likely arises from a synergistic combination of (i) compromised fitness of bacteria in planta; (ii) decreased efficiency of type III translocation; and (iii) cytoplasmically retained virulence factors. Finally, we demonstrate a novel broad-host-range genetic reporter based on the green fluorescent protein for the identification of Tat-targeted secreted virulence factors that should be generally applicable to any gram-negative bacterium. Collectively, our evidence supports the notion that virulence of DC3000 is a multifactorial process and that the Tat system is an important virulence determinant of this phytopathogenic bacterium.

scholarly journals Multiple Activities of the Plant Pathogen Type III Effector Proteins WtsE and AvrE Require WxxxE Motifs

2009 ◽  
Vol 22 (6) ◽  
pp. 703-712 ◽  
Author(s):  
Jong Hyun Ham ◽  
Doris R. Majerczak ◽  
Kinya Nomura ◽  
Christy Mecey ◽  
Francisco Uribe ◽  
...  
Keyword(s):  
G Proteins ◽  
Pseudomonas Syringae ◽  
Virulence Factors ◽  
Pathogenic Bacteria ◽  
Plant Pathogens ◽  
Biological Activities ◽  
Defense Responses ◽  
Endoplasmic Reticulum Membrane ◽  
Type Iii Effectors ◽  
Type Iii

The broadly conserved AvrE-family of type III effectors from gram-negative plant-pathogenic bacteria includes important virulence factors, yet little is known about the mechanisms by which these effectors function inside plant cells to promote disease. We have identified two conserved motifs in AvrE-family effectors: a WxxxE motif and a putative C-terminal endoplasmic reticulum membrane retention/retrieval signal (ERMRS). The WxxxE and ERMRS motifs are both required for the virulence activities of WtsE and AvrE, which are major virulence factors of the corn pathogen Pantoea stewartii subsp. stewartii and the tomato or Arabidopsis pathogen Pseudomonas syringae pv. tomato, respectively. The WxxxE and the predicted ERMRS motifs are also required for other biological activities of WtsE, including elicitation of the hypersensitive response in nonhost plants and suppression of defense responses in Arabidopsis. A family of type III effectors from mammalian bacterial pathogens requires WxxxE and subcellular targeting motifs for virulence functions that involve their ability to mimic activated G-proteins. The conservation of related motifs and their necessity for the function of type III effectors from plant pathogens indicates that disturbing host pathways by mimicking activated host G-proteins may be a virulence mechanism employed by plant pathogens as well.

scholarly journals HrpL Regulon of Bacterial Pathogen of Woody Host Pseudomonas savastanoi pv. savastanoi NCPPB 3335

2021 ◽  
Vol 9 (7) ◽  
pp. 1447
Author(s):  
Alba Moreno-Pérez ◽  
Cayo Ramos ◽  
Luis Rodríguez-Moreno
Keyword(s):  
Virulence Factors ◽  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Bacterial Pathogen ◽  
Rna Seq ◽  
Whole Transcriptome Sequencing ◽  
Pathogenicity Tests ◽  
Rapid Activation ◽  
Whole Transcriptome ◽  
Woody Host

The Pseudomonas savastanoi species comprises a group of phytopathogenic bacteria that cause symptoms of disease in woody hosts. This is mediated by the rapid activation of a pool of virulence factors that suppress host defences and hijack the host’s metabolism to the pathogen’s benefit. The hrpL gene encodes an essential transcriptional regulator of virulence functions, including the type III secretion system (T3SS), in pathogenic bacteria. Here, we analyzed the contribution of HrpL to the virulence of four pathovars (pv.) of P. savastanoi isolated from different woody hosts (oleander, ash, broom, and dipladenia) and characterized the HrpL regulon of P. savastanoi pv. savastanoi NCPPB 3335 using two approaches: whole transcriptome sequencing (RNA-seq) and the bioinformatic prediction of candidate genes containing an hrp-box. Pathogenicity tests carried out for the P. savastanoi pvs. showed that HrpL was essential for symptom development in both non-host and host plants. The RNA-seq analysis of the HrpL regulon in P. savastanoi revealed a total of 53 deregulated genes, 49 of which were downregulated in the ΔhrpL mutant. Bioinformatic prediction resulted in the identification of 50 putative genes containing an hrp-box, 16 of which were shared with genes previously identified by RNA-seq. Although most of the genes regulated by HrpL belonged to the T3SS, we also identified some genes regulated by HrpL that could encode potential virulence factors in P. savastanoi.

scholarly journals Identification and Functional Analysis of Type III Effector Proteins in Mesorhizobium loti

2010 ◽  
Vol 23 (2) ◽  
pp. 223-234 ◽  
Author(s):  
Shin Okazaki ◽  
Saori Okabe ◽  
Miku Higashi ◽  
Yoshikazu Shimoda ◽  
Shusei Sato ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Rhizobium Leguminosarum ◽  
Plant Pathogens ◽  
Effector Proteins ◽  
Sequence Motif ◽  
Shikimate Kinase ◽  
Model Legume ◽  
Type Iii Effector ◽  
Mesorhizobium Loti ◽  
Type Iii

Mesorhizobium loti MAFF303099, a microsymbiont of the model legume Lotus japonicus, possesses a cluster of genes (tts) that encode a type III secretion system (T3SS). In the presence of heterologous nodD from Rhizobium leguminosarum and a flavonoid naringenin, we observed elevated expression of the tts genes and secretion of several proteins into the culture medium. Inoculation experiments with wild-type and T3SS mutant strains revealed that the presence of the T3SS affected nodulation at a species level within the Lotus genus either positively (L. corniculatus subsp. frondosus and L. filicaulis) or negatively (L. halophilus and two other species). By inoculating L. halophilus with mutants of various type III effector candidate genes, we identified open reading frame mlr6361 as a major determinant of the nodulation restriction observed for L. halophilus. The predicted gene product of mlr6361 is a protein of 3,056 amino acids containing 15 repetitions of a sequence motif of 40 to 45 residues and a shikimate kinase-like domain at its carboxyl terminus. Homologues with similar repeat sequences are present in the hypersensitive-response and pathogenicity regions of several plant pathogens, including strains of Pseudomonas syringae, Ralstonia solanacearum, and Xanthomonas species. These results suggest that L. halophilus recognizes Mlr6361 as potentially pathogen derived and subsequently halts the infection process.

Sign in / Sign up

Export Citation Format

Share Document