scholarly journals Identification of Loci of Pseudomonas syringae pv. actinidiae Involved in Lipolytic Activity and Their Role in Colonization of Kiwifruit Leaves

2017 ◽  
Vol 107 (6) ◽  
pp. 645-653 ◽  
Author(s):  
Hitendra Kumar Patel ◽  
Patrizia Ferrante ◽  
Meng Xianfa ◽  
Sree Gowrinadh Javvadi ◽  
Sujatha Subramoni ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Pathogens ◽  
Lipid A ◽  
Lipolytic Activity ◽  
Genetic Screen ◽  
Economic Losses ◽  
In Planta ◽  
Tn5 Transposon ◽  
Tn5 Mutants ◽  
Transposon Mutants

Bacterial canker disease caused by Pseudomonas syringae pv. actinidiae, an emerging pathogen of kiwifruit plants, has recently brought about major economic losses worldwide. Genetic studies on virulence functions of P. syringae pv. actinidiae have not yet been reported and there is little experimental data regarding bacterial genes involved in pathogenesis. In this study, we performed a genetic screen in order to identify transposon mutants altered in the lipolytic activity because it is known that mechanisms of regulation, production, and secretion of enzymes often play crucial roles in virulence of plant pathogens. We aimed to identify the set of secretion and global regulatory loci that control lipolytic activity and also play important roles in in planta fitness. Our screen for altered lipolytic activity phenotype identified a total of 58 Tn5 transposon mutants. Mapping all these Tn5 mutants revealed that the transposons were inserted in genes that play roles in cell division, chemotaxis, metabolism, movement, recombination, regulation, signal transduction, and transport as well as a few unknown functions. Several of these identified P. syringae pv. actinidiae Tn5 mutants, notably the functions affected in phosphomannomutase AlgC, lipid A biosynthesis acyltransferase, glutamate–cysteine ligase, and the type IV pilus protein PilI, were also found affected in in planta survival and/or growth in kiwifruit plants. The results of the genetic screen and identification of novel loci involved in in planta fitness of P. syringae pv. actinidiae are presented and discussed.

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 Effectiveness of Dunaliella salina Extracts against Bacillus subtilis and Bacterial Plant Pathogens

Pathogens ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 613
Author(s):  
Alfredo Ambrico ◽  
Mario Trupo ◽  
Rosaria Magarelli ◽  
Roberto Balducchi ◽  
Angelo Ferraro ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Pseudomonas Syringae ◽  
Dunaliella Salina ◽  
Plant Pathogens ◽  
Plant Diseases ◽  
Economic Losses ◽  
Tomato Plants ◽  
Hexane Extracts

Several bacteria pathogens are responsible for plant diseases causing significant economic losses. The antibacterial activity of Dunaliella salina microalgae extracts were investigated in vitro and in vivo. First, biomass composition was chemically characterized and subjected to extraction using polar/non-polar solvents. The highest extraction yield was obtained using chloroform:methanol (1:1 v/v) equal to 170 mg g−1 followed by ethanol (88 mg g−1) and hexane (61 mg g−1). In vitro examination of hexane extracts of Dunaliella salina demonstrated antibacterial activity against all tested bacteria. The hexane extract showed the highest amount of β-carotene with respect to the others, so it was selected for subsequent analyses. In vivo studies were also carried out using hexane extracts of D. salina against Pseudomonas syringae pv. tomato and Pectobacterium carotovorum subsp. carotovorum on young tomato plants and fruits of tomato and zucchini, respectively. The treated young tomato plants exhibited a reduction of 65.7% incidence and 77.0% severity of bacterial speck spot disease. Similarly, a reduction of soft rot symptoms was observed in treated tomato and zucchini fruits with a disease incidence of 5.3% and 12.6% with respect to 90.6% and 100%, respectively, for the positive control.

scholarly journals Characterization of the RND-Type Multidrug Efflux Pump MexAB-OprM of the Plant Pathogen Pseudomonas syringae

2008 ◽  
Vol 74 (11) ◽  
pp. 3387-3393 ◽  
Author(s):  
Savina O. Stoitsova ◽  
Yvonne Braun ◽  
Matthias S. Ullrich ◽  
Helge Weingart
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Pathogens ◽  
Efflux Pump ◽  
Blot Hybridization ◽  
In Planta ◽  
Multidrug Efflux ◽  
Dot Blot ◽  
Multidrug Efflux Pump

ABSTRACT In gram-negative bacteria, transporters belonging to the RND family are the transporters most relevant for resistance to antimicrobial compounds. In Pseudomonas aeruginosa, a clinically important pathogen, the RND-type pump MexAB-OprM has been recognized as one of the major multidrug efflux systems. Here, homologues of MexAB-OprM in the plant pathogens Pseudomonas syringae pv. phaseolicola 1448A, P. syringae pv. syringae B728a, and P. syringae pv. tomato DC3000 were identified, and mexAB-oprM-deficient mutants were generated. Determination of MICs revealed that mutation of MexAB-OprM dramatically reduced the tolerance to a broad range of antimicrobials. Moreover, the ability of the mexAB-oprM-deficient mutants to multiply in planta was reduced. RNA dot blot hybridization revealed growth-dependent regulation of the mexAB-oprM operon in P. syringae; the expression of this operon was maximal in early exponential phase and decreased gradually during further growth.

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 Comparative genomics ofPseudomonas syringaepathovartomatoreveals novel chemotaxis pathways associated with motility and plant pathogenicity

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2570 ◽  
Author(s):  
Christopher R. Clarke ◽  
Byron W. Hayes ◽  
Brendan J. Runde ◽  
Eric Markel ◽  
Bryan M. Swingle ◽  
...  
Keyword(s):  
Comparative Genomics ◽  
Pseudomonas Syringae ◽  
Host Plants ◽  
Plant Pathogens ◽  
Gene Clusters ◽  
In Planta ◽  
Kinase Gene ◽  
Host Interaction ◽  
Type Iv ◽  
Flagellar Biosynthesis

The majority of bacterial foliar plant pathogens must invade the apoplast of host plants through points of ingress, such as stomata or wounds, to replicate to high population density and cause disease. How pathogens navigate plant surfaces to locate invasion sites remains poorly understood. Many bacteria use chemical-directed regulation of flagellar rotation, a process known as chemotaxis, to move towards favorable environmental conditions. Chemotactic sensing of the plant surface is a potential mechanism through which foliar plant pathogens home in on wounds or stomata, but chemotactic systems in foliar plant pathogens are not well characterized. Comparative genomics of the plant pathogenPseudomonas syringaepathovartomato(Pto) implicated annotated chemotaxis genes in the recent adaptations of one Pto lineage. We therefore characterized the chemosensory system of Pto. The Pto genome contains two primary chemotaxis gene clusters,che1andche2. Theche2cluster is flanked by flagellar biosynthesis genes and similar to the canonical chemotaxis gene clusters of other bacteria based on sequence and synteny. Disruption of the primary phosphorelay kinase gene of theche2cluster,cheA2, eliminated all swimming and surface motility at 21  °C but not 28  °C for Pto. Theche1cluster is located next to Type IV pili biosynthesis genes but disruption ofcheA1has no observable effect on twitching motility for Pto. Disruption ofcheA2also altersin plantafitness of the pathogen with strains lacking functionalcheA2being less fit in host plants but more fit in a non-host interaction.

scholarly journals A DeoR-Type Transcription Regulator Is Required for Sugar-Induced Expression of Type III Secretion-Encoding Genes in Pseudomonas syringae pv. tomato DC3000

2020 ◽  
Vol 33 (3) ◽  
pp. 509-518 ◽  
Author(s):  
Sydney E. Turner ◽  
Yin-Yuin Pang ◽  
Megan R. O’Malley ◽  
Alexandra J. Weisberg ◽  
Valerie N. Fraser ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Type Iii Secretion ◽  
Molecular Mechanisms ◽  
In Planta ◽  
Induced Expression ◽  
Tn5 Transposon ◽  
Type Iii ◽  
Genes Encoding ◽  
Tn5 Mutant ◽  
Encoding Genes

The type III secretion system (T3SS) of plant-pathogenic Pseudomonas syringae is essential for virulence. Genes encoding the T3SS are not constitutively expressed and must be induced upon infection. Plant-derived metabolites, including sugars such as fructose and sucrose, are inducers of T3SS-encoding genes, yet the molecular mechanisms underlying perception of these host signals by P. syringae are unknown. Here, we report that sugar-induced expression of type III secretion A (setA), predicted to encode a DeoR-type transcription factor, is required for maximal sugar-induced expression of T3SS-associated genes in P. syringae DC3000. From a Tn5 transposon mutagenesis screen, we identified two independent mutants with insertions in setA. When both setA::Tn5 mutants were cultured in minimal medium containing fructose, genes encoding the T3SS master regulator HrpL and effector AvrRpm1 were expressed at lower levels relative to that of a wild-type strain. Decreased hrpL and avrRpm1 expression also occurred in a setA::Tn5 mutant in response to glucose, sucrose, galactose, and mannitol, demonstrating that setA is genetically required for T3SS induction by many different sugars. Expression of upstream regulators hrpR/S and rpoN was not altered in setA::Tn5, indicating that SetA positively regulates hrpL expression independently of increased transcription of these genes. In addition to decreased response to defined sugar signals, a setA::Tn5 mutant had decreased T3SS deployment during infection and was compromised in its ability to grow in planta and cause disease. These data suggest that SetA is necessary for P. syringae to effectively respond to T3SS-inducing sugar signals encountered during infection.

scholarly journals Dual Role of Auxin in Regulating Plant Defense and Bacterial Virulence Gene Expression During Pseudomonas syringae PtoDC3000 Pathogenesis

2020 ◽  
Vol 33 (8) ◽  
pp. 1059-1071 ◽  
Author(s):  
Arnaud T. Djami-Tchatchou ◽  
Gregory A. Harrison ◽  
Chris P. Harper ◽  
Renhou Wang ◽  
Michael J. Prigge ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Bacterial Growth ◽  
Plant Pathogens ◽  
Virulence Gene ◽  
Bacterial Virulence ◽  
Auxin Signaling ◽  
Host Defenses ◽  
In Planta ◽  
Virulence Gene Expression

Modification of host hormone biology is a common strategy used by plant pathogens to promote disease. For example, the bacterial pathogen strain Pseudomonas syringae DC3000 (PtoDC3000) produces the plant hormone auxin (indole-3-acetic acid [IAA]) to promote PtoDC3000 growth in plant tissue. Previous studies suggest that auxin may promote PtoDC3000 pathogenesis through multiple mechanisms, including both suppression of salicylic acid (SA)-mediated host defenses and via an unknown mechanism that appears to be independent of SA. To test if host auxin signaling is important during pathogenesis, we took advantage of Arabidopsis thaliana lines impaired in either auxin signaling or perception. We found that disruption of auxin signaling in plants expressing an inducible dominant axr2-1 mutation resulted in decreased bacterial growth and that this phenotype was suppressed by introducing the sid2-2 mutation, which impairs SA synthesis. Thus, host auxin signaling is required for normal susceptibility to PtoDC3000 and is involved in suppressing SA-mediated defenses. Unexpectedly, tir1 afb1 afb4 afb5 quadruple-mutant plants lacking four of the six known auxin coreceptors that exhibit decreased auxin perception, supported increased levels of bacterial growth. This mutant exhibited elevated IAA levels and reduced SA-mediated defenses, providing additional evidence that auxin promotes disease by suppressing host defense. We also investigated the hypothesis that IAA promotes PtoDC3000 virulence through a direct effect on the pathogen and found that IAA modulates expression of virulence genes, both in culture and in planta. Thus, in addition to suppressing host defenses, IAA acts as a microbial signaling molecule that regulates bacterial virulence gene expression.

scholarly journals A Breach in Plant Defences: Pseudomonas syringae pv. actinidiae Targets Ethylene Signalling to Overcome Actinidia chinensis Pathogen Responses

2021 ◽  
Vol 22 (9) ◽  
pp. 4375
Author(s):  
Antonio Cellini ◽  
Irene Donati ◽  
Brian Farneti ◽  
Iuliia Khomenko ◽  
Giampaolo Buriani ◽  
...  
Keyword(s):  
Immune Responses ◽  
Pseudomonas Syringae ◽  
Ethylene Production ◽  
Plant Pathogens ◽  
In Planta ◽  
Virulence Trait ◽  
Exogenous Ethylene ◽  
Ethylene Signalling ◽  
Highly Virulent

Ethylene interacts with other plant hormones to modulate many aspects of plant metabolism, including defence and stomata regulation. Therefore, its manipulation may allow plant pathogens to overcome the host’s immune responses. This work investigates the role of ethylene as a virulence factor for Pseudomonas syringae pv. actinidiae (Psa), the aetiological agent of the bacterial canker of kiwifruit. The pandemic, highly virulent biovar of this pathogen produces ethylene, whereas the biovars isolated in Japan and Korea do not. Ethylene production is modulated in planta by light/dark cycle. Exogenous ethylene application stimulates bacterial virulence, and restricts or increases host colonisation if performed before or after inoculation, respectively. The deletion of a gene, unrelated to known bacterial biosynthetic pathways and putatively encoding for an oxidoreductase, abolishes ethylene production and reduces the pathogen growth rate in planta. Ethylene production by Psa may be a recently and independently evolved virulence trait in the arms race against the host. Plant- and pathogen-derived ethylene may concur in the activation/suppression of immune responses, in the chemotaxis toward a suitable entry point, or in the endophytic colonisation.

scholarly journals Inhibition of Fungal and Bacterial Plant Pathogens In Vitro and In Planta with Ultrashort Cationic Lipopeptides

2007 ◽  
Vol 73 (20) ◽  
pp. 6629-6636 ◽  
Author(s):  
Arik Makovitzki ◽  
Ada Viterbo ◽  
Yariv Brotman ◽  
Ilan Chet ◽  
Yechiel Shai
Keyword(s):  
Pseudomonas Syringae ◽  
Pathogenic Bacteria ◽  
Plant Pathogens ◽  
Antimicrobial Agents ◽  
Plant Protection ◽  
Microscopic Analysis ◽  
Plant Diseases ◽  
In Planta ◽  
Global Food Security

ABSTRACT Plant diseases constitute an emerging threat to global food security. Many of the currently available antimicrobial agents for agriculture are highly toxic and nonbiodegradable and cause extended environmental pollution. Moreover, an increasing number of phytopathogens develop resistance to them. Recently, we have reported on a new family of ultrashort antimicrobial lipopeptides which are composed of only four amino acids linked to fatty acids (A. Makovitzki, D. Avrahami, and Y. Shai, Proc. Natl. Acad. Sci. USA 103:15997-16002, 2006). Here, we investigated the activities in vitro and in planta and the modes of action of these short lipopeptides against plant-pathogenic bacteria and fungi. They act rapidly, at low micromolar concentrations, on the membranes of the microorganisms via a lytic mechanism. In vitro microscopic analysis revealed wide-scale damage to the microorganism's membrane, in addition to inhibition of pathogen growth. In planta potent antifungal activity was demonstrated on cucumber fruits and leaves infected with the pathogen Botrytis cinerea as well as on corn leaves infected with Cochliobolus heterostrophus. Similarly, treatment with the lipopeptides of Arabidopsis leaves infected with the bacterial leaf pathogen Pseudomonas syringae efficiently and rapidly reduced the number of bacteria. Importantly, in contrast to what occurred with many native lipopeptides, no toxicity was observed on the plant tissues. These data suggest that the ultrashort lipopeptides could serve as native-like antimicrobial agents economically feasible for use in plant protection.

scholarly journals Dual role of auxin in regulating plant defense and bacterial virulence gene expression during Pseudomonas syringae PtoDC3000 pathogenesis

2019 ◽  
Author(s):  
Arnaud T. Djami-Tchatchou ◽  
Gregory A. Harrison ◽  
Chris P. Harper ◽  
Renhou Wang ◽  
Michael J. Prigge ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Bacterial Growth ◽  
Plant Pathogens ◽  
Virulence Gene ◽  
Bacterial Virulence ◽  
Auxin Signaling ◽  
Host Defenses ◽  
In Planta ◽  
Virulence Gene Expression

ABSTRACTModification of host hormone biology is a common strategy used by plant pathogens to promote disease. For example, the bacterial pathogen Pseudomonas syringae strain PtoDC3000 produces the plant hormone auxin (Indole-3-acetic acid, or IAA) to promote PtoDC3000 growth in plant tissue. Previous studies suggest that auxin may promote PtoDC3000 pathogenesis through multiple mechanisms, including both suppression of salicylic acid (SA)-mediated host defenses and via an unknown mechanism that appears to be independent of SA. To test if host auxin signaling is important during pathogenesis, we took advantage of Arabidopsis thaliana lines impaired in either auxin signaling or perception. We found that disruption of auxin signaling in plants expressing an inducible dominant axr2-1 mutation resulted in decreased bacterial growth, demonstrating that host auxin signaling is required for normal susceptibility to PtoDC3000, and this phenotype was dependent on SA-mediated defenses. However, despite exhibiting decreased auxin perception, tir1 afb1 afb4 afb5 quadruple mutant plants lacking four of the six known auxin co-receptors supported increased levels of bacterial growth. This mutant also exhibited elevated IAA levels, suggesting that the increased IAA in these plants may promote PtoDC3000 growth independent of host auxin signaling, perhaps through a direct effect on the pathogen. In support of this, we found that IAA directly impacted the pathogen, by modulating expression of bacterial virulence genes, both in liquid culture and in planta. Thus, in addition to suppressing host defenses, IAA acts as a microbial signaling molecule that regulates bacterial virulence gene expression.

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