scholarly journals Tomato 14-3-3 Proteins Are Required for Xv3 Disease Resistance and Interact with a Subset of Xanthomonas euvesicatoria Effectors

2018 ◽  
Vol 31 (12) ◽  
pp. 1301-1311 ◽  
Author(s):  
Zoe Dubrow ◽  
Sukumaran Sunitha ◽  
Jung-Gun Kim ◽  
Chris D. Aakre ◽  
Anil Madhusoodana Girija ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Type Iii Secretion ◽  
Peptide Mapping ◽  
Bacterial Pathogen ◽  
Effector Proteins ◽  
In Planta ◽  
Pathogen Effectors ◽  
Xanthomonas Euvesicatoria ◽  
Type Iii Secretion Effector ◽  
Susceptible Tomato

The 14-3-3 phospho-binding proteins with scaffolding activity play central roles in the regulation of enzymes and signaling complexes in eukaryotes. In plants, 14-3-3 isoforms are required for disease resistance and key targets of pathogen effectors. Here, we examined the requirement of the tomato (Solanum lycopersicum) 14-3-3 isoform (TFT) protein family for Xv3 disease resistance in response to the bacterial pathogen Xanthomonas euvesicatoria. In addition, we determined whether TFT proteins interact with the repertoire of X. euvesicatoria type III secretion effector proteins, including AvrXv3, the elicitor of Xv3 resistance. We show that multiple TFT contribute to Xv3 resistance. We also show that one or more TFT proteins physically interact with multiple effectors (AvrXv3, XopE1, XopE2, XopN, XopO, XopQ, and XopAU). Genetic analyses indicate that none of the identified effectors interfere with AvrXv3-elicited resistance into Xv3 tomato leaves; however, XopE1, XopE2, and XopO are required to suppress symptom development in susceptible tomato leaves. Phospho-peptide mapping revealed that XopE2 is phosphorylated at multiple residues in planta and residues T66, T131, and S334 are required for maximal binding to TFT10. Together, our data support the hypothesis that multiple TFT proteins are involved in immune signaling during X. euvesicatoria infection.

scholarly journals Multiple Xanthomonas euvesicatoria Type III Effectors Inhibit flg22-Triggered Immunity

2016 ◽  
Vol 29 (8) ◽  
pp. 651-660 ◽  
Author(s):  
Georgy Popov ◽  
Malou Fraiture ◽  
Frederic Brunner ◽  
Guido Sessa
Keyword(s):  
Pseudomonas Syringae ◽  
Map Kinases ◽  
Molecular Mechanisms ◽  
Inducible Promoter ◽  
Effector Proteins ◽  
Host Cells ◽  
In Planta ◽  
Callose Deposition ◽  
Type Iii ◽  
Xanthomonas Euvesicatoria

Xanthomonas euvesicatoria is the causal agent of bacterial spot disease in pepper and tomato. X. euvesicatoria bacteria interfere with plant cellular processes by injecting effector proteins into host cells through the type III secretion (T3S) system. About 35 T3S effectors have been identified in X. euvesicatoria 85-10, and a few of them were implicated in suppression of pattern-triggered immunity (PTI). We used an Arabidopsis thaliana pathogen-free protoplast–based assay to identify X. euvesicatoria 85-10 effectors that interfere with PTI signaling induced by the bacterial peptide flg22. Of 33 tested effectors, 17 inhibited activation of a PTI-inducible promoter. Among them, nine effectors also interfered with activation of an abscisic acid–inducible promoter. However, effectors that inhibited flg22-induced signaling did not affect phosphorylation of mitogen-activated protein (MAP) kinases acting downstream of flg22 perception. Further investigation of selected effectors revealed that XopAJ, XopE2, and XopF2 inhibited activation of a PTI-inducible promoter by the bacterial peptide elf18 in Arabidopsis protoplasts and by flg22 in tomato protoplasts. The effectors XopF2, XopE2, XopAP, XopAE, XopH, and XopAJ inhibited flg22-induced callose deposition in planta and enhanced disease symptoms caused by attenuated Pseudomonas syringae bacteria. Finally, selected effectors were found to localize to various plant subcellular compartments. These results indicate that X. euvesicatoria bacteria utilize multiple T3S effectors to suppress flg22-induced signaling acting downstream or in parallel to MAP kinase cascades and suggest they act through different molecular mechanisms.

scholarly journals A Bacterial Type III Secretion Assay for Delivery of Fungal Effector Proteins into Wheat

2014 ◽  
Vol 27 (3) ◽  
pp. 255-264 ◽  
Author(s):  
Narayana M. Upadhyaya ◽  
Rohit Mago ◽  
Brian J. Staskawicz ◽  
Michael A. Ayliffe ◽  
Jeffrey G. Ellis ◽  
...  
Keyword(s):  
Pseudomonas Fluorescens ◽  
Delivery System ◽  
Type Iii Secretion ◽  
Large Scale ◽  
Rust Fungus ◽  
Effector Proteins ◽  
In Planta ◽  
Host Genotype ◽  
Reporter Protein ◽  
Type Iii

Large numbers of candidate effectors from fungal pathogens are being identified through whole-genome sequencing and in planta expression studies. Although Agrobacterium-mediated transient expression has enabled high-throughput functional analysis of effectors in dicot plants, this assay is not effective in cereal leaves. Here, we show that a nonpathogenic Pseudomonas fluorescens engineered to express the type III secretion system (T3SS) of P. syringae and the wheat pathogen Xanthomonas translucens can deliver fusion proteins containing T3SS signals from P. syringae (AvrRpm1) and X. campestris (AvrBs2) avirulence (Avr) proteins, respectively, into wheat leaf cells. A calmodulin-dependent adenylate cyclase reporter protein was delivered effectively into wheat and barley by both bacteria. Absence of any disease symptoms with P. fluorescens makes it more suitable than X. translucens for detecting a hypersensitive response (HR) induced by an effector protein with avirulence activity. We further modified the delivery system by removal of the myristoylation site from the AvrRpm1 fusion to prevent its localization to the plasma membrane which could inhibit recognition of an Avr protein. Delivery of the flax rust AvrM protein by the modified delivery system into transgenic tobacco leaves expressing the corresponding M resistance protein induced a strong HR, indicating that the system is capable of delivering a functional rust Avr protein. In a preliminary screen of effectors from the stem rust fungus Puccinia graminis f. sp. tritici, we identified one effector that induced a host genotype-specific HR in wheat. Thus, the modified AvrRpm1:effector–Pseudomonas fluorescens system is an effective tool for large-scale screening of pathogen effectors for recognition in wheat.

scholarly journals Functional Analysis of Plant Defense Suppression and Activation by the Xanthomonas Core Type III Effector XopX

2015 ◽  
Vol 28 (2) ◽  
pp. 180-194 ◽  
Author(s):  
William Stork ◽  
Jung-Gun Kim ◽  
Mary Beth Mudgett
Keyword(s):  
Plant Defense ◽  
Defense Responses ◽  
Effector Proteins ◽  
Immune Signaling ◽  
Type Iii ◽  
Effector Triggered Immunity ◽  
Gene Transcripts ◽  
Type Iii Secretion Effector ◽  
Susceptible Tomato

Many phytopathogenic type III secretion effector proteins (T3Es) have been shown to target and suppress plant immune signaling but perturbation of the plant immune system by T3Es can also elicit a plant response. XopX is a “core” Xanthomonas T3E that contributes to growth and symptom development during Xanthomonas euvesicatoria infection of tomato but its functional role is undefined. We tested the effect of XopX on several aspects of plant immune signaling. XopX promoted ethylene production and plant cell death (PCD) during X. euvesicatoria infection of susceptible tomato and in transient expression assays in Nicotiana benthamiana, which is consistent with its requirement for the development of X. euvesicatoria-induced disease symptoms. Additionally, although XopX suppressed flagellin-induced reactive oxygen species, it promoted the accumulation of pattern-triggered immunity (PTI) gene transcripts. Surprisingly, XopX coexpression with other PCD elicitors resulted in delayed PCD, suggesting antagonism between XopX-dependent PCD and other PCD pathways. However, we found no evidence that XopX contributed to the suppression of effector-triggered immunity during X. euvesicatoria–tomato interactions, suggesting that XopX's primary virulence role is to modulate PTI. These results highlight the dual role of a core Xanthomonas T3E in simultaneously suppressing and activating plant defense responses.

scholarly journals N-hydroxy-pipecolic acid is a mobile signal that induces systemic disease resistance in Arabidopsis

2018 ◽  
Author(s):  
Yun Chu Chen ◽  
Eric C. Holmes ◽  
Jakub Rajniak ◽  
Jung-Gun Kim ◽  
Sandy Tang ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Systemic Acquired Resistance ◽  
Systemic Disease ◽  
Acquired Resistance ◽  
Bacterial Pathogen ◽  
Pipecolic Acid ◽  
In Planta ◽  
Global Response ◽  
Promising Target ◽  
Pathogenesis Related

AbstractSystemic acquired resistance (SAR) is a global response in plants induced at the site of infection that leads to long-lasting and broad-spectrum disease resistance at distal, uninfected tissues. Despite the importance of this priming mechanism, the identity of the mobile defense signal that moves systemically throughout plants to initiate SAR has remained elusive. In this paper, we describe a new metabolite, N-hydroxy-pipecolic acid (N-OH-Pip), and provide evidence that this molecule is a mobile signal that plays a central role in initiating SAR signal transduction in Arabidopsis thaliana. We demonstrate that FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1), a key regulator of SAR-associated defense priming, can synthesize N-OH-Pip from pipecolic acid in planta, and exogenously applied N-OH-PIP moves systemically in Arabidopsis and can rescue the SAR-deficiency of fmo1 mutants. We also demonstrate that N-OH-Pip treatment causes systemic changes in the expression of pathogenesis-related genes and metabolic pathways throughout the plant, and enhances resistance to a bacterial pathogen. This work provides new insight into the chemical nature of a mobile signal for SAR and also suggests that the N-OH-Pip pathway is a promising target for metabolic engineering to enhance disease resistance.

scholarly journals Verticillium dahliae effector VDAL protects MYB6 from degradation by interacting with PUB25/26 E3 ligases for enhancing Verticillium wilt resistance in Arabidopsis

2021 ◽  
Author(s):  
Zhizhong Gong ◽  
Junsheng Qi ◽  
Aifang Ma ◽  
Dingpeng Zhang ◽  
Guangxing Wang ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Verticillium Wilt ◽  
Verticillium Dahliae ◽  
Plant Resistance ◽  
Plant Disease Resistance ◽  
Plant Disease ◽  
Effector Proteins ◽  
In Planta ◽  
E3 Ligases

Verticillium wilt is a severe plant disease, increasing the plant resistance to this disease is a critical challenge worldwide. Here, we report that the Verticillium dahliae (V. dahliae)-secreted Aspf2-like protein VDAL causes leaf wilting when applied to cotton leaves in vitro, but enhances the resistance to V. dahliae when overexpressed in Arabidopsis or cotton. VDAL interacts with Arabidopsis E3 ligases PUB25 and PUB26 (PUBs) and is ubiquitinated by PUBs in vitro. However, VDAL is not degraded by PUBs in planta. Besides, the pub25 pub26 shows higher resistance to V. dahliae than the wild type. PUBs interact with the transcription factor MYB6 in a yeast two-hybrid screen. MYB6 promotes plant resistance to Verticillium wilt while PUBs ubiquitinate MYB6 and mediate its degradation. VDAL competes with MYB6 for binding to PUBs, and the role of VDAL in increasing wilt disease depends on MYB6. These results suggest that plants evolute a strategy to utilize the invaded effector protein VDAL to resist the V. dahliae infection without causing a hypersensitive response. This study provides the molecular mechanism for plants increasing disease resistance when overexpressing some effector proteins, and may promote searching for more genes from pathogenic fungi or bacteria to engineer plant disease resistance.

scholarly journals Pseudomonas Type III Effector AvrPto Suppresses the Programmed Cell Death Induced by Two Nonhost Pathogens in Nicotiana benthamiana and Tomato

2004 ◽  
Vol 17 (12) ◽  
pp. 1328-1336 ◽  
Author(s):  
Li Kang ◽  
Xiaoyan Tang ◽  
Kirankumar S. Mysore
Keyword(s):  
Cell Death ◽  
Disease Resistance ◽  
Programmed Cell Death ◽  
Pseudomonas Syringae ◽  
Type Iii Secretion ◽  
Nicotiana Benthamiana ◽  
Effector Proteins ◽  
Type Iii ◽  
Bacterial Pathogenicity ◽  
Suppression Effects

Many gram-negative bacterial pathogens rely on a type III secretion system to deliver a number of effector proteins into the host cell. Though a number of these effectors have been shown to contribute to bacterial pathogenicity, their functions remain elusive. Here we report that AvrPto, an effector known for its ability to interact with Pto and induce Pto-mediated disease resistance, inhibited the hypersensitive response (HR) induced by nonhost pathogen interactions. Pseudomonas syringae pv. tomato T1 causes an HR-like cell death on Nicotiana benthamiana. This rapid cell death was delayed significantly in plants inoculated with P. syringae pv. tomato expressing avrPto. In addition, P. syringae pv. tabaci expressing avrPto suppressed nonhost HR on tomato prf3 and ptoS lines. Transient expression of avrPto in both N. benthamiana and tomato prf3 plants also was able to suppress nonhost HR. Interestingly, AvrPto failed to suppress cell death caused by other elicitors and nonhost pathogens. AvrPto also failed to suppress cell death caused by certain gene-for-gene disease resistance interactions. Experiments with avrPto mutants revealed several residues important for the suppression effects. AvrPto mutants G2A, G99V, P146L, and a 12-amino-acid C-terminal deletion mutant partially lost the suppression ability, whereas S94P and I96T enhanced suppression of cell death in N. benthamiana. These results, together with other discoveries, demonstrated that suppression of host-programmed cell death may serve as one of the strategies bacterial pathoens use for successful invasion.

scholarly journals Basal Resistance Against Pseudomonas syringae in Arabidopsis Involves WRKY53 and a Protein with Homology to a Nematode Resistance Protein

2007 ◽  
Vol 20 (11) ◽  
pp. 1431-1438 ◽  
Author(s):  
Shane L. Murray ◽  
Robert A. Ingle ◽  
Lindsay N. Petersen ◽  
Katherine J. Denby
Keyword(s):  
Pseudomonas Syringae ◽  
Bacterial Pathogen ◽  
Nematode Resistance ◽  
Host Recognition ◽  
In Planta ◽  
Basal Resistance ◽  
Pathogen Effectors ◽  
Positive Regulators ◽  
Resistance Protein ◽  
Molecular Patterns

Basal resistance is the ultimately unsuccessful plant defense response to infection with a virulent pathogen. It is thought to be triggered by host recognition of pathogen-associated molecular patterns, with subsequent suppression of particular components by pathogen effectors. To identify novel components of Arabidopsis basal resistance against the bacterial pathogen Pseudomonas syringae pv. tomato, microarray expression profiling was carried out on the cir1 mutant, which displays enhanced resistance against P. syringae pv. tomato. This identified two genes, At4g23810 and At2g40000, encoding the transcription factor WRKY53 and the nematode resistance protein-like HSPRO2, whose expression was upregulated in cir1 prior to pathogen infection and in wild-type plants after P. syringae pv. tomato infection. WRKY53 and HSPRO2 are positive regulators of basal resistance. Knockout mutants of both genes were more susceptible to P. syringae pv. tomato infection than complemented lines, with increased growth of the pathogen in planta. WRKY53 and HSPRO2 appear to function downstream of salicylic acid and to be negatively regulated by signaling through jasmonic acid and ethylene.

scholarly journals Naturally Occurring Nonpathogenic Isolates of the Plant Pathogen Pseudomonas syringae Lack a Type III Secretion System and Effector Gene Orthologues

2008 ◽  
Vol 190 (8) ◽  
pp. 2858-2870 ◽  
Author(s):  
Toni J. Mohr ◽  
Haijie Liu ◽  
Shuangchun Yan ◽  
Cindy E. Morris ◽  
José A. Castillo ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Type Iii Secretion ◽  
Plant Cells ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Plant Diseases ◽  
In Planta ◽  
Type Iii ◽  
Effector Gene

ABSTRACT Pseudomonas syringae causes plant diseases, and the main virulence mechanism is a type III secretion system (T3SS) that translocates dozens of effector proteins into plant cells. Here we report the existence of a subgroup of P. syringae isolates that do not cause disease on any plant species tested. This group is monophyletic and most likely evolved from a pathogenic P. syringae ancestor through loss of the T3SS. In the nonpathogenic isolate P. syringae 508 the genomic region that in pathogenic P. syringae strains contains the hrp-hrc cluster coding for the T3SS and flanking effector genes is absent. P. syringae 508 was also surveyed for the presence of effector orthologues from the closely related pathogenic strain P. syringae pv. syringae B728a, but none were detected. The absence of the hrp-hrc cluster and effector orthologues was confirmed for other nonpathogenic isolates. Using the AvrRpt2 effector as reporter revealed the inability of P. syringae 508 to translocate effectors into plant cells. Adding a plasmid-encoded T3SS and the P. syringae pv. syringae 61 effector gene hopA1 increased in planta growth almost 10-fold. This suggests that P. syringae 508 supplemented with a T3SS could be used to determine functions of individual effectors in the context of a plant infection, avoiding the confounding effect of other effectors with similar functions present in effector mutants of pathogenic isolates.

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