scholarly journals Phytotoxin synthesis genes and type III effector genes of Pseudomonas syringae pv. actinidiae biovar 6 are regulated by culture conditions

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9697
Author(s):  
Karin Hirose ◽  
Yasuhiro Ishiga ◽  
Takashi Fujikawa
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Environmental Changes ◽  
Culture Media ◽  
Type Iii Effector ◽  
Type Iii ◽  
Effector Genes ◽  
The Media ◽  
Inducible Genes

The kiwifruit bacterial canker (Pseudomonas syringae pv. actinidiae; Psa) causes severe damage to kiwifruit production worldwide. Psa biovar 6 (Psa6), which was isolated in Japan in 2015, produces two types of phytotoxins: coronatine and phaseolotoxin. To elucidate the unique virulence of Psa6, we performed transcriptomic analysis of phytotoxin synthesis genes and type III effector genes in in vitro cultivation using various media. The genes related to phytotoxin synthesis and effectors of Psa6 were strictly regulated in the coronatine-inducing mediums (HS and HSC); 14 of 23 effector genes and a hrpL sigma factor gene were induced at 3 h after transferring to the media (early-inducible genes), and phytotoxin synthesis genes such as argD of phaseolotoxin and cfl of coronatine were induced at 6 and 12 h after transferring to the media (late-inducible genes). In contrast, induction of these genes was not observed in the hrp-inducing medium. Next, to examine whether the changes in gene expression in different media is specific to Psa6, we investigated gene expression in other related bacteria. For Psa biovar 1 (Psa1), biovar 3 (Psa3), and P. s. pv. glycinea (Psg), no clear trends were observed in expression behavior across various culture media and incubation times. Therefore, Psa6 seems to exert its virulence efficiently by using two phytotoxins and effectors according to environmental changes. This is not seen in other biovars and pathovars, so it is thought that Psa6 has acquired its own balance of virulence.

scholarly journals Phytotoxin synthesis genes and type III effector genes of Pseudomonas syringae pv. actinidiae biovar 6 are regulated by culture conditions

2020 ◽  
Author(s):  
Karin Hirose ◽  
Yasuhiro Ishiga ◽  
Takashi Fujikawa
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Environmental Changes ◽  
Culture Media ◽  
Type Iii Effector ◽  
Type Iii ◽  
Effector Genes ◽  
The Media ◽  
Inducible Genes

AbstractThe kiwifruit bacterial canker (Pseudomonas syringae pv. actinidiae; Psa) causes severe damage to kiwifruit production worldwide. Psa biovar 6 (Psa6), which was isolated in Japan in 2015, produces two types of phytotoxins: coronatine and phaseolotoxin. To date, no other phytopathogenic bacteria are known to produce two phytotoxins. To elucidate the unique virulence of Psa6, we performed transcriptomic analysis of phytotoxin synthesis genes and type III effector genes in in vitro cultivation using various media. The genes related to phytotoxin synthesis and effectors of Psa6 were strictly regulated in the coronatine-inducing mediums (HS and HSC); 14 of 23 effector genes and a hrpL sigma factor gene were induced at 3 h after transferring to the media (early-inducible genes), and phytotoxin synthesis genes such as argD of phaseolotoxin and cfl of coronatine were induced at 6 and 12 h after transferring to the media (late-inducible genes). In contrast, induction of these genes was not observed in the hrp-inducing medium. Next, to examine whether the changes in gene expression in different media is specific to Psa6, we investigated gene expression in other related bacteria. For Psa biovar 1 (Psa1), biovar 3 (Psa3), and P. s. pv. glycinea (Psg), no clear trends were observed in expression behavior across various culture media and incubation times. Therefore, Psa6 seems to exert its virulence efficiently by using two phytotoxins and effectors according to environmental changes. This is not seen in other biovars and pathovars, so it is thought that Psa6 has acquired its own balance of virulence.

scholarly journals Negative Regulation of the Hrp Type III Secretion System in Pseudomonas syringae pv. phaseolicola

2010 ◽  
Vol 23 (5) ◽  
pp. 682-701 ◽  
Author(s):  
Inmaculada Ortiz-Martín ◽  
Richard Thwaites ◽  
John W. Mansfield ◽  
Carmen R. Beuzón
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
In Planta ◽  
Secretion Systems ◽  
Type Iii ◽  
Type Iii Secretion Systems ◽  
Bacterial Fitness

Many plant-pathogenic bacteria require type III secretion systems (T3SS) to cause disease in compatible hosts and to induce the hypersensitive response in resistant plants. T3SS gene expression is induced within the plant and responds to host and environmental factors. In Pseudomonas syringae, expression is downregulated by the Lon protease in rich medium and by HrpV under inducing conditions. HrpV acts as an anti-activator by binding HrpS. HrpG, which can also bind HrpV, has been reported to act as an anti-anti-activator. Previous studies have used mostly in vitro inducing conditions, different pathovars, and methodology. We have used single and double lon and hrpV mutants of P. syringae pv. phaseolicola 1448a, as well as strains ectopically expressing the regulators, to examine their role in coordinating expression of the T3SS. We applied real-time polymerase chain reaction to analyze gene expression both in vitro and in planta, and assessed bacterial fitness using competitive indices. Our results indicate that i) Lon downregulates expression of the hrp/hrc genes in all conditions, probably by constitutively degrading naturally unstable HrpR; ii) HrpV and HrpT downregulate expression of the hrp/hrc genes in all conditions; and iii) HrpG has an additional, HrpV-independent role, regulating expression of the hrpC operon.

scholarly journals A Remorin from Nicotiana benthamiana Interacts with the Pseudomonas Type-III Effector Protein HopZ1a and is Phosphorylated by the Immune-Related Kinase PBS1

2019 ◽  
Vol 32 (9) ◽  
pp. 1229-1242 ◽  
Author(s):  
Philip Albers ◽  
Suayib Üstün ◽  
Katja Witzel ◽  
Max Kraner ◽  
Frederik Börnke
Keyword(s):  
Pseudomonas Syringae ◽  
Nicotiana Benthamiana ◽  
Effector Protein ◽  
Type Iii Effector ◽  
Defense Signaling ◽  
Type Iii ◽  
Target Membrane ◽  
Effector Triggered Immunity ◽  
Transient Overexpression

The plasma membrane (PM) is at the interface of plant–pathogen interactions and, thus, many bacterial type-III effector (T3E) proteins target membrane-associated processes to interfere with immunity. The Pseudomonas syringae T3E HopZ1a is a host cell PM-localized effector protein that has several immunity-associated host targets but also activates effector-triggered immunity in resistant backgrounds. Although HopZ1a has been shown to interfere with early defense signaling at the PM, no dedicated PM-associated HopZ1a target protein has been identified until now. Here, we show that HopZ1a interacts with the PM-associated remorin protein NbREM4 from Nicotiana benthamiana in several independent assays. NbREM4 relocalizes to membrane nanodomains after treatment with the bacterial elicitor flg22 and transient overexpression of NbREM4 in N. benthamiana induces the expression of a subset of defense-related genes. We can further show that NbREM4 interacts with the immune-related receptor-like cytoplasmic kinase avrPphB-susceptible 1 (PBS1) and is phosphorylated by PBS1 on several residues in vitro. Thus, we conclude that NbREM4 is associated with early defense signaling at the PM. The possible relevance of the HopZ1a–NbREM4 interaction for HopZ1a virulence and avirulence functions is discussed. [Formula: see text]Copyright © 2019 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Positive Regulation of the Hrp Type III Secretion System in Pseudomonas syringae pv. phaseolicola

2010 ◽  
Vol 23 (5) ◽  
pp. 665-681 ◽  
Author(s):  
Inmaculada Ortiz-Martín ◽  
Richard Thwaites ◽  
Alberto P. Macho ◽  
John W. Mansfield ◽  
Carmen R. Beuzón
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Hypersensitive Response ◽  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Virulence Determinants ◽  
Type Iii

Disease in compatible hosts and induction of the hypersensitive response in resistant plants by most plant-pathogenic bacteria require a functional type III secretion system (T3SS). Expression of T3SS genes responds to host and environmental factors and is induced within the plant. In Pseudomonas syringae, expression of the T3SS requires HrpL, which is transcriptionally upregulated by HrpR and HrpS. In some pathovars, expression of the hrpRS genes is upregulated by the GacA/S two-component system. Additionally, HrpA, the major component of the T3SS pilus, has also been linked to the regulation of the hrpRS gene expression. Previous studies concerning regulation of hypersensitive response and pathogenesis/hypersensitive response conserved (hrp/hrc) gene expression have used mostly in vitro inducing conditions, different pathovars, and methodology. Here, we analyze the roles of HrpL, GacA, and HrpA in the bean pathogen, using single, double, and triple mutants as well as strains ectopically expressing the regulators. We use real-time polymerase chain reaction analysis in vitro and in planta to quantify gene expression and competitive indices and other assays to assess bacterial fitness. Our results indicate that i) HrpL acts as a general virulence regulator that upregulates non-T3SS virulence determinants and downregulates flagellar function; ii) GacA modulates the expression of hrpL, and its contribution to virulence is entirely HrpL dependent; iii) there is a basal HrpL-independent expression of the T3SS genes in rich medium that is important for full activation of the system, maybe by keeping the system primed for rapid activation upon contact with the plant; and iv) HrpA upregulates expression of the T3SS genes and is essential to activate expression of the hrpZ operon upon contact with the plant.

scholarly journals A remorin from Nicotiana benthamiana interacts with the Pseudomonas type-III effector protein HopZ1a and is phosphorylated by the immune-related kinase PBS1

2018 ◽  
Author(s):  
Philip Albers ◽  
Suayib Üstün ◽  
Katja Witzel ◽  
Max Kraner ◽  
Frederik Börnke
Keyword(s):  
Plasma Membrane ◽  
Pseudomonas Syringae ◽  
Nicotiana Benthamiana ◽  
Effector Proteins ◽  
Effector Protein ◽  
Type Iii Effector ◽  
Defense Signaling ◽  
Type Iii ◽  
Transient Overexpression

AbstractThe plasma membrane is at the interface of plant-pathogen interactions and thus many bacterial type-III effector proteins (T3Es) target membrane-associated processes to interfere with immunity. The Pseudomonas syringae T3E is a host cell plasma membrane (PM)-localized effector protein that has several immunity associated host targets but also activates effector triggered immunity (ETI) in resistant backgrounds. Although HopZ1a has been shown to interfere with early defense signaling at the PM, no dedicated plasma membrane-associated HopZ1a target protein has been identified until now. We show here, that HopZ1a interacts with the PM-associated remorin protein NbREM4 from Nicotiana benthamiana in several independent assays. NbREM4 re-localizes to membrane sub-domains after treatment with the bacterial elicitor flg22 and transient overexpression of NbREM4 in N. benthamiana induces the expression of a subset of defense related genes. We can further show that NbREM4 interacts with the immune-related receptor-like cytoplasmic kinase PBS1 and is phosphorylated by PBS1 on several residues in vitro. Thus, we conclude that NbREM4 is associated with early defense signaling at the PM. The possible relevance of the HopZ1a/NbREM4 interaction for HopZ1a virulence and avirulence functions is discussed.

scholarly journals A high-throughput, near-saturating screen for type III effector genes from Pseudomonas syringae

2005 ◽  
Vol 102 (7) ◽  
pp. 2549-2554 ◽  
Author(s):  
J. H. Chang ◽  
J. M. Urbach ◽  
T. F. Law ◽  
L. W. Arnold ◽  
A. Hu ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
High Throughput ◽  
Type Iii Effector ◽  
Type Iii ◽  
Effector Genes
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