scholarly journals Plant immunity triggered by engineered in vivo release of oligogalacturonides, damage-associated molecular patterns

2015 ◽  
Vol 112 (17) ◽  
pp. 5533-5538 ◽  
Author(s):  
Manuel Benedetti ◽  
Daniela Pontiggia ◽  
Sara Raggi ◽  
Zhenyu Cheng ◽  
Flavio Scaloni ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
Inducible Promoter ◽  
Spectrometric Analysis ◽  
In Planta ◽  
Gene Encoding ◽  
Polygalacturonase Inhibiting Protein ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns

Oligogalacturonides (OGs) are fragments of pectin that activate plant innate immunity by functioning as damage-associated molecular patterns (DAMPs). We set out to test the hypothesis that OGs are generated in planta by partial inhibition of pathogen-encoded polygalacturonases (PGs). A gene encoding a fungal PG was fused with a gene encoding a plant polygalacturonase-inhibiting protein (PGIP) and expressed in transgenic Arabidopsis plants. We show that expression of the PGIP–PG chimera results in the in vivo production of OGs that can be detected by mass spectrometric analysis. Transgenic plants expressing the chimera under control of a pathogen-inducible promoter are more resistant to the phytopathogens Botrytis cinerea, Pectobacterium carotovorum, and Pseudomonas syringae. These data provide strong evidence for the hypothesis that OGs released in vivo act as a DAMP signal to trigger plant immunity and suggest that controlled release of these molecules upon infection may be a valuable tool to protect plants against infectious diseases. On the other hand, elevated levels of expression of the chimera cause the accumulation of salicylic acid, reduced growth, and eventually lead to plant death, consistent with the current notion that trade-off occurs between growth and defense.

scholarly journals The bacterial effector HopZ1a acetylates MKK7 to suppress plant immunity

2020 ◽  
Author(s):  
José S. Rufián ◽  
Javier Rueda-Blanco ◽  
Diego López-Márquez ◽  
Alberto P. Macho ◽  
Carmen R. Beuzón ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
Inducible Promoter ◽  
Effector Proteins ◽  
Mitogen Activated Protein Kinase ◽  
In Planta ◽  
Systemic Immunity ◽  
Mitogen Activated Protein ◽  
Ros Burst

ABSTRACTThe Pseudomonas syringae type III secretion system translocates effector proteins into the host cell cytosol, suppressing plant basal immunity triggered upon recognition of pathogen-associated molecular patterns (PAMPs), and effector-triggered immunity. Effector HopZ1a suppresses local and systemic immunity triggered by PAMPs and effectors, through target acetylation. HopZ1a has been shown to target several plant proteins, but none fully substantiates HopZ1a-associated immune suppression. Here, we investigate Arabidopsis thaliana mitogen-activated protein kinase kinases (MKKs) as potential targets, focusing on AtMKK7, a positive regulator of local and systemic immunity. We analyse HopZ1a interference with AtMKK7 by translocation of HopZ1a from bacteria inoculated into Arabidopsis expressing MKK7 from an inducible promoter. Reciprocal phenotypes are analysed on plants expressing a construct quenching MKK7 native expression. We analyse HopZ1a-MKK7 interaction by three independent methods, and the relevance of acetylation by in vitro kinase and in planta functional assays. We demonstrate AtMKK7 contribution to immune signalling showing MKK7-dependent flg22-induced ROS burst, MAPK activation, and callose accumulation, plus AvrRpt2-triggered MKK7-dependent signalling. Further, we demonstrate HopZ1a suppression of all MKK7-dependent responses, HopZ1a-MKK7 interaction in planta, and HopZ1a acetylation of MKK7 in a lysine required for full kinase activity. We demonstrate that HopZ1a targets AtMKK7 to suppress local and systemic plant immunity.

A vector system for fast-forward studies of the HOPZ-ACTIVATED RESISTANCE1 (ZAR1) resistosome in the model plant Nicotiana benthamiana

2021 ◽  
Author(s):  
Adeline Harant ◽  
Hsuan Pai ◽  
Toshiyuki Sakai ◽  
Sophien Kamoun ◽  
Hiroaki Adachi
Keyword(s):  
Nicotiana Benthamiana ◽  
Cell Biology ◽  
Plant Immunity ◽  
Transient Gene Expression ◽  
Coiled Coil ◽  
Experimental System ◽  
Vector System ◽  
In Planta ◽  
Functional Studies

Abstract Nicotiana benthamiana has emerged as a complementary experimental system to Arabidopsis thaliana. It enables fast-forward in vivo analyses primarily through transient gene expression and is particularly popular in the study of plant immunity. Recently, our understanding of nucleotide-binding leucine-rich repeat (NLR) plant immune receptors has greatly advanced following the discovery of the Arabidopsis HOPZ-ACTIVATED RESISTANCE1 (ZAR1) resistosome. Here, we describe a vector system of 72 plasmids that enables functional studies of the ZAR1 resistosome in N. benthamiana. We showed that ZAR1 stands out among the coiled coil class of NLRs (CC-NLRs) for being highly conserved across distantly related dicot plant species and confirmed NbZAR1 as the N. benthamiana ortholog of Arabidopsis ZAR1. Effector-activated and autoactive NbZAR1 trigger the cell death response in N. benthamiana and this activity is dependent on a functional N-terminal α1 helix. C-terminally tagged NbZAR1 remains functional in N. benthamiana, thus enabling cell biology and biochemical studies in this plant system. We conclude that the NbZAR1 open source pZA plasmid collection forms an additional experimental system to Arabidopsis for in planta resistosome studies.

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 P03.24 Calreticulin exposure on malignant blasts correlates with improved NK cell-mediated cytotoxicity in AML patients

2020 ◽  
Vol 8 (Suppl 2) ◽  
pp. A32.1-A32
Author(s):  
I Truxova ◽  
L Kasikova ◽  
C Salek ◽  
M Hensler ◽  
D Lysak ◽  
...  
Keyword(s):  
Nk Cells ◽  
Cell Activation ◽  
Nk Cell ◽  
Type I ◽  
Danger Signals ◽  
Hla Dr ◽  
Patient Prognosis ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns

In some settings, cancer cells responding to treatment undergo an immunogenic form of cell death that is associated with the abundant emission of danger signals in the form of damage-associated molecular patterns. Accumulating preclinical and clinical evidence indicates that danger signals play a crucial role in the (re-)activation of antitumor immune responses in vivo, thus having a major impact on patient prognosis. We have previously demonstrated that the presence of calreticulin on the surface of malignant blasts is a positive prognostic biomarker for patients with acute myeloid leukemia (AML). Calreticulin exposure not only correlated with enhanced T-cell-dependent antitumor immunity in this setting but also affected the number of circulating natural killer (NK) cells upon restoration of normal hematopoiesis. Here, we report that calreticulin exposure on malignant blasts is associated with enhanced NK cell cytotoxic and secretory functions, both in AML patients and in vivo in mice. The ability of calreticulin to stimulate NK-cells relies on CD11c+CD14high cells that, upon exposure to CRT, express higher levels of IL-15Rα, maturation markers (CD86 and HLA- DR) and CCR7. CRT exposure on malignant blasts also correlates with the upregulation of genes coding for type I interferon. This suggests that CD11c+CD14high cells have increased capacity to migrate to secondary lymphoid organs, where can efficiently deliver stimulatory signals (IL-15Rα/IL- 15) to NK cells. These findings delineate a multipronged, clinically relevant mechanism whereby surface-exposed calreticulin favors NK-cell activation in AML patients.Disclosure InformationI. Truxova: None. L. Kasikova: None. C. Salek: None. M. Hensler: None. D. Lysak: None. P. Holicek: None. P. Bilkova: None. M. Holubova: None. X. Chen: None. R. Mikyskova: None. M. Reinis: None. M. Kovar: None. B. Tomalova: None. J.P. Kline: None. L. Galluzzi: None. R. Spisek: None. J. Fucikova: None.

scholarly journals Cysteine protease RD21A regulated by E3 ligase SINAT4 is required for drought-induced resistance to Pseudomonas syringae in Arabidopsis

2020 ◽  
Vol 71 (18) ◽  
pp. 5562-5576
Author(s):  
Yi Liu ◽  
Kunru Wang ◽  
Qiang Cheng ◽  
Danyu Kong ◽  
Xunzhong Zhang ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Cysteine Protease ◽  
Plant Immunity ◽  
Stomatal Closure ◽  
Bacterial Pathogen ◽  
E3 Ligase ◽  
Biotic Stresses ◽  
Ubiquitin E3 Ligase ◽  
Induced Immunity

Abstract Plants can be simultaneously exposed to multiple stresses. The interplay of abiotic and biotic stresses may result in synergistic or antagonistic effects on plant development and health. Temporary drought stress can stimulate plant immunity; however, the molecular mechanism of drought-induced immunity is largely unknown. In this study, we demonstrate that cysteine protease RD21A is required for drought-induced immunity. Temporarily drought-treated wild-type Arabidopsis plants became more sensitive to the bacterial pathogen-associated molecular pattern flg22, triggering stomatal closure, which resulted in increased resistance to Pseudomonas syringae pv. tomato DC3000 (Pst-DC3000). Knocking out rd21a inhibited flg22-triggered stomatal closure and compromised the drought-induced immunity. Ubiquitin E3 ligase SINAT4 interacted with RD21A and promoted its degradation in vivo. The overexpression of SINAT4 also consistently compromised the drought-induced immunity to Pst-DC3000. A bacterial type III effector, AvrRxo1, interacted with both SINAT4 and RD21A, enhancing SINAT4 activity and promoting the degradation of RD21A in vivo. Therefore, RD21A could be a positive regulator of drought-induced immunity, which could be targeted by pathogen virulence effectors during pathogenesis.

scholarly journals A putative nuclear copper chaperone promotes plant immunity in Arabidopsis

2020 ◽  
Vol 71 (20) ◽  
pp. 6684-6696 ◽  
Author(s):  
Long-Xiang Chai ◽  
Kai Dong ◽  
Song-Yu Liu ◽  
Zhen Zhang ◽  
Xiao-Peng Zhang ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Plant Immunity ◽  
Copper Chaperone ◽  
Copper Binding ◽  
Nuclear Speckles ◽  
Defense Gene Expression ◽  
Copper Chaperones ◽  
Plant Nucleus

Abstract Copper is essential for many metabolic processes but must be sequestrated by copper chaperones. It is well known that plant copper chaperones regulate various physiological processes. However, the functions of copper chaperones in the plant nucleus remain largely unknown. Here, we identified a putative copper chaperone induced by pathogens (CCP) in Arabidopsis thaliana. CCP harbors a classical MXCXXC copper-binding site (CBS) at its N-terminus and a nuclear localization signal (NLS) at its C-terminus. CCP mainly formed nuclear speckles in the plant nucleus, which requires the NLS and CBS domains. Overexpression of CCP induced PR1 expression and enhanced resistance against Pseudomonas syringae pv. tomato DC3000 compared with Col-0 plants. Conversely, two CRISPR/Cas9-mediated ccp mutants were impaired in plant immunity. Further biochemical analyses revealed that CCP interacted with the transcription factor TGA2 in vivo and in vitro. Moreover, CCP recruits TGA2 to the PR1 promoter sequences in vivo, which induces defense gene expression and plant immunity. Collectively, our results have identified a putative nuclear copper chaperone required for plant immunity and provided evidence for a potential function of copper in the salicylic pathway.

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 Identification of Genes in Xanthomonas campestris pv. vesicatoria Induced during Its Interaction with Tomato

2007 ◽  
Vol 189 (17) ◽  
pp. 6359-6371 ◽  
Author(s):  
Dafna Tamir-Ariel ◽  
Naama Navon ◽  
Saul Burdman
Keyword(s):  
Xanthomonas Campestris ◽  
Disease Process ◽  
In Planta ◽  
Gene Encoding ◽  
Host Interaction ◽  
Citrate Transporter ◽  
Knockout Mutants ◽  
Bacterial Spot Disease

ABSTRACT Xanthomonas campestris pv. vesicatoria is the causal agent of bacterial spot disease of tomato and pepper. The disease process is interactive and very intricate and involves a plethora of genes in the pathogen and in the host. In the pathogen, different genes are activated in response to the changing environment to enable it to survive, adapt, evade host defenses, propagate, and damage the host. To understand the disease process, it is imperative to broaden our understanding of the gene machinery that participates in it, and the most reliable way is to identify these genes in vivo. Here, we have adapted a recombinase-based in vivo expression technology (RIVET) to study the genes activated in X. campestris pv. vesicatoria during its interaction with one of its hosts, tomato. This is the first study that demonstrates the feasibility of this approach for identifying in vivo induced genes in a plant pathogen. RIVET revealed 61 unique X. campestris pv. vesicatoria genes or operons that delineate a picture of the different processes involved in the pathogen-host interaction. To further explore the role of some of these genes, we generated knockout mutants for 13 genes and characterized their ability to grow in planta and to cause disease symptoms. This analysis revealed several genes that may be important for the interaction of the pathogen with its host, including a citH homologue gene, encoding a citrate transporter, which was shown to be required for wild-type levels of virulence.

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