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1.
Int J Mol Sci ; 22(19)2021 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-34639149

RESUMO

Fungal enzymes degrading the plant cell wall, such as xylanases, can activate plant immune responses. The Fusarium graminearum FGSG_03624 xylanase, previously shown to elicit necrosis and hydrogen peroxide accumulation in wheat, was investigated for its ability to induce disease resistance. To this aim, we transiently and constitutively expressed an enzymatically inactive form of FGSG_03624 in tobacco and Arabidopsis, respectively. The plants were challenged with Pseudomonas syringae pv. tabaci or pv. maculicola and Botrytis cinerea. Symptom reduction by the bacterium was evident, while no reduction was observed after B. cinerea inoculation. Compared to the control, the presence of the xylanase gene in transgenic Arabidopsis plants did not alter the basal expression of a set of defense-related genes, and, after the P. syringae inoculation, a prolonged PR1 expression was detected. F. graminearum inoculation experiments of durum wheat spikes exogenously treated with the FGSG_03624 xylanase highlighted a reduction of symptoms in the early phases of infection and a lower fungal biomass accumulation than in the control. Besides, callose deposition was detected in infected spikes previously treated with the xylanase and not in infected control plants. In conclusion, our results highlight the ability of FGSG_03624 to enhance plant immunity, thus decreasing disease severity.


Assuntos
Arabidopsis/imunologia , Botrytis/patogenicidade , Resistência à Doença/imunologia , Endo-1,4-beta-Xilanases/metabolismo , Fusarium/enzimologia , Imunidade Vegetal , Pseudomonas syringae/patogenicidade , Tabaco/imunologia , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Tabaco/metabolismo , Tabaco/microbiologia
2.
BMC Plant Biol ; 21(1): 429, 2021 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-34548030

RESUMO

BACKGROUND: Surveillance of potential pathogens is a key feature of plant innate immunity. For non-self-recognition plants rely on the perception of pathogen-derived molecules. Early post-perception events activate signaling cascades, leading to the synthesis of defense-related proteins and specialized metabolites, thereby providing a broad-spectrum antimicrobial coverage. This study was concerned with tracking changes in the tomato plant metabolome following perception of the flagellum-derived elicitors (Flg22 and FlgII-28). RESULTS: Following an untargeted metabolomics workflow, the metabolic profiles of a Solanum lycopersicum cultivar were monitored over a time range of 16-32 h post-treatment. Liquid chromatography was used to resolve the complex mixture of metabolites and mass spectrometry for the detection of differences associated with the elicitor treatments. Stringent data processing and multivariate statistical tools were applied to the complex dataset to extract relevant metabolite features associated with the elicitor treatments. Following perception of Flg22 and FlgII-28, both elicitors triggered an oxidative burst, albeit with different kinetic responses. Signatory biomarkers were annotated from diverse metabolite classes which included amino acid derivatives, lipid species, steroidal glycoalkaloids, hydroxybenzoic acids, hydroxycinnamic acids and derivatives, as well as flavonoids. CONCLUSIONS: An untargeted metabolomics approach adequately captured the subtle and nuanced perturbations associated with elicitor-linked plant defense responses. The shared and unique features characterizing the metabolite profiles suggest a divergence of signal transduction events following perception of Flg22 vs. FlgII-28, leading to a differential reorganization of downstream metabolic pathways.


Assuntos
Resistência à Doença/genética , Resistência à Doença/imunologia , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Pseudomonas syringae/patogenicidade , Produtos Agrícolas/genética , Produtos Agrícolas/metabolismo , Produtos Agrícolas/microbiologia , Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/microbiologia , Metabolômica
3.
BMC Plant Biol ; 21(1): 425, 2021 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-34537002

RESUMO

BACKGROUND: The Catharanthus roseus RLK1-like kinase (CrRLK1L) is a subfamily of the RLK gene family, and members are sensors of cell wall integrity and regulators of cell polarity growth. Recent studies have also shown that members of this subfamily are involved in plant immunity. Nicotiana benthamiana is a model plant widely used in the study of plant-pathogen interactions. However, the members of the NbCrRLK1L subfamily and their response to pathogens have not been reported. RESULTS: In this study, a total of 31 CrRLK1L members were identified in the N. benthamiana genome, and these can be divided into 6 phylogenetic groups (I-VI). The members in each group have similar exon-intron structures and conserved motifs. NbCrRLK1Ls were predicted to be regulated by cis-acting elements such as STRE, TCA, ABRE, etc., and to be the target of transcription factors such as Dof and MYB. The expression profiles of the 16 selected NbCrRLK1Ls were determined by quantitative PCR. Most NbCrRLK1Ls were highly expressed in leaves but there were different and diverse expression patterns in other tissues. Inoculation with the bacterium Pseudomonas syringae or with Turnip mosaic virus significantly altered the transcript levels of the tested genes, suggesting that NbCrRLK1Ls may be involved in the response to pathogens. CONCLUSIONS: This study systematically identified the CrRLK1L members in N. benthamiana, and analyzed their tissue-specific expression and gene expression profiles in response to different pathogens and two pathogens associated molecular patterns (PAMPs). This research lays the foundation for exploring the function of NbCrRLK1Ls in plant-microbe interactions.


Assuntos
Catharanthus/genética , Proteínas de Plantas/genética , Proteínas Quinases/genética , Tabaco/genética , Catharanthus/enzimologia , Regulação da Expressão Gênica de Plantas , Genoma de Planta , Interações Hospedeiro-Patógeno , Filogenia , Imunidade Vegetal/genética , Folhas de Planta/genética , Folhas de Planta/virologia , Proteínas de Plantas/metabolismo , Regiões Promotoras Genéticas , Domínios Proteicos , Proteínas Quinases/metabolismo , Pseudomonas syringae/patogenicidade , Tabaco/microbiologia , Tabaco/virologia , Fatores de Transcrição/genética
4.
Int J Mol Sci ; 22(15)2021 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-34361108

RESUMO

Alfalfa has emerged as one of the most important forage crops, owing to its wide adaptation and high biomass production worldwide. In the last decade, the emergence of bacterial stem blight (caused by Pseudomonas syringae pv. syringae ALF3) in alfalfa has caused around 50% yield losses in the United States. Studies are being conducted to decipher the roles of the key genes and pathways regulating the disease, but due to the sparse knowledge about the infection mechanisms of Pseudomonas, the development of resistant cultivars is hampered. The database alfaNET is an attempt to assist researchers by providing comprehensive Pseudomonas proteome annotations, as well as a host-pathogen interactome tool, which predicts the interactions between host and pathogen based on orthology. alfaNET is a user-friendly and efficient tool and includes other features such as subcellular localization annotations of pathogen proteins, gene ontology (GO) annotations, network visualization, and effector protein prediction. Users can also browse and search the database using particular keywords or proteins with a specific length. Additionally, the BLAST search tool enables the user to perform a homology sequence search against the alfalfa and Pseudomonas proteomes. With the successful implementation of these attributes, alfaNET will be a beneficial resource to the research community engaged in implementing molecular strategies to mitigate the disease. alfaNET is freely available for public use at http://bioinfo.usu.edu/alfanet/.


Assuntos
Proteínas de Bactérias/metabolismo , Bases de Dados de Proteínas , Interações Hospedeiro-Patógeno , Medicago sativa/metabolismo , Doenças das Plantas/imunologia , Mapas de Interação de Proteínas , Pseudomonas syringae/patogenicidade , Medicago sativa/imunologia , Medicago sativa/microbiologia , Doenças das Plantas/microbiologia
5.
Plant Cell ; 33(3): 735-749, 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33955489

RESUMO

The tradeoff between growth and defense is a critical aspect of plant immunity. Therefore, the plant immune response needs to be tightly regulated. Salicylic acid (SA) is an important plant hormone regulating defense against biotrophic pathogens. Recently, N-hydroxy-pipecolic acid (NHP) was identified as another regulator for plant innate immunity and systemic acquired resistance (SAR). Although the biosynthetic pathway leading to NHP formation is already been identified, how NHP is further metabolized is unclear. Here, we present UGT76B1 as a uridine diphosphate-dependent glycosyltransferase (UGT) that modifies NHP by catalyzing the formation of 1-O-glucosyl-pipecolic acid in Arabidopsis thaliana. Analysis of T-DNA and clustered regularly interspaced short palindromic repeats (CRISPR) knock-out mutant lines of UGT76B1 by targeted and nontargeted ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) underlined NHP and SA as endogenous substrates of this enzyme in response to Pseudomonas infection and UV treatment. ugt76b1 mutant plants have a dwarf phenotype and constitutive defense response which can be suppressed by loss of function of the NHP biosynthetic enzyme FLAVIN-DEPENDENT MONOOXYGENASE 1 (FMO1). This suggests that elevated accumulation of NHP contributes to the enhanced disease resistance in ugt76b1. Externally applied NHP can move to distal tissue in ugt76b1 mutant plants. Although glycosylation is not required for the long-distance movement of NHP during SAR, it is crucial to balance growth and defense.


Assuntos
Proteínas de Arabidopsis/metabolismo , Glicosiltransferases/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Regulação da Expressão Gênica de Plantas , Glicosiltransferases/genética , Ácidos Pipecólicos/metabolismo , Imunidade Vegetal/genética , Imunidade Vegetal/fisiologia , Pseudomonas syringae/patogenicidade , Ácido Salicílico/metabolismo
6.
Plant Cell ; 33(3): 750-765, 2021 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-33955491

RESUMO

Systemic acquired resistance (SAR) is a mechanism that plants utilize to connect a local pathogen infection to global defense responses. N-hydroxy-pipecolic acid (NHP) and a glycosylated derivative are produced during SAR, yet their individual roles in this process are currently unclear. Here, we report that Arabidopsis thaliana UGT76B1 generated glycosylated NHP (NHP-Glc) in vitro and when transiently expressed alongside Arabidopsis NHP biosynthetic genes in two Solanaceous plants. During infection, Arabidopsis ugt76b1 mutants did not accumulate NHP-Glc and accumulated less glycosylated salicylic acid (SA-Glc) than wild-type plants. The metabolic changes in ugt76b1 plants were accompanied by enhanced defense to the bacterial pathogen Pseudomonas syringae, suggesting that glycosylation of the SAR molecules NHP and salicylic acid by UGT76B1 plays an important role in modulating defense responses. Transient expression of Arabidopsis UGT76B1 with the Arabidopsis NHP biosynthesis genes ALD1 and FMO1 in tomato (Solanum lycopersicum) increased NHP-Glc production and reduced NHP accumulation in local tissue and abolished the systemic resistance seen when expressing NHP-biosynthetic genes alone. These findings reveal that the glycosylation of NHP by UGT76B1 alters defense priming in systemic tissue and provide further evidence for the role of the NHP aglycone as the active metabolite in SAR signaling.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Ácidos Pipecólicos/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Imunidade Inata/fisiologia , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Doenças das Plantas/microbiologia , Imunidade Vegetal/fisiologia , Pseudomonas syringae/patogenicidade
7.
Nat Commun ; 12(1): 2739, 2021 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-34016974

RESUMO

In addition to conspicuous large mesophyll chloroplasts, where most photosynthesis occurs, small epidermal chloroplasts have also been observed in plant leaves. However, the functional significance of this small organelle remains unclear. Here, we present evidence that Arabidopsis epidermal chloroplasts control the entry of fungal pathogens. In entry trials, specialized fungal cells called appressoria triggered dynamic movement of epidermal chloroplasts. This movement is controlled by common regulators of mesophyll chloroplast photorelocation movement, designated as the epidermal chloroplast response (ECR). The ECR occurs when the PEN2 myrosinase-related higher-layer antifungal system becomes ineffective, and blockage of the distinct steps of the ECR commonly decreases preinvasive nonhost resistance against fungi. Furthermore, immune components were preferentially localized to epidermal chloroplasts, contributing to antifungal nonhost resistance in the pen2 background. Our findings reveal that atypical small chloroplasts act as defense-related motile organelles by specifically positioning immune components in the plant epidermis, which is the first site of contact between the plant and pathogens. Thus, this work deepens our understanding of the functions of epidermal chloroplasts.


Assuntos
Arabidopsis/imunologia , Cloroplastos/imunologia , Resistência à Doença/imunologia , Doenças das Plantas/imunologia , Epiderme Vegetal/imunologia , Arabidopsis/genética , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Auxilinas/genética , Auxilinas/metabolismo , Proteínas de Cloroplastos/genética , Proteínas de Cloroplastos/metabolismo , Cloroplastos/metabolismo , Colletotrichum/imunologia , Colletotrichum/patogenicidade , Interações Hospedeiro-Patógeno/imunologia , Magnaporthe/imunologia , Magnaporthe/patogenicidade , Proteínas dos Microfilamentos/genética , Proteínas dos Microfilamentos/metabolismo , Mutação , N-Glicosil Hidrolases/genética , N-Glicosil Hidrolases/metabolismo , Doenças das Plantas/microbiologia , Epiderme Vegetal/citologia , Epiderme Vegetal/metabolismo , Epiderme Vegetal/microbiologia , Folhas de Planta/citologia , Folhas de Planta/imunologia , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Plantas Geneticamente Modificadas , Pseudomonas syringae/imunologia , Pseudomonas syringae/patogenicidade
8.
Plant J ; 107(1): 149-165, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33866633

RESUMO

Recent studies have shown that global metabolic reprogramming is a common event in plant innate immunity; however, the relevant molecular mechanisms remain largely unknown. Here, we identified a pathogen-induced glycosyltransferase, UGT73C7, that plays a critical role in Arabidopsis disease resistance through mediating redirection of the phenylpropanoid pathway. Loss of UGT73C7 function resulted in significantly decreased resistance to Pseudomonas syringae pv. tomato DC3000, whereas constitutive overexpression of UGT73C7 led to an enhanced defense response. UGT73C7-activated immunity was demonstrated to be dependent on the upregulated expression of SNC1, a Toll/interleukin 1 receptor-type NLR gene. Furthermore, in vitro and in vivo assays indicated that UGT73C7 could glycosylate p-coumaric acid and ferulic acid, the upstream metabolites in the phenylpropanoid pathway. Mutations that lead to the loss of UGT73C7 enzyme activities resulted in the failure to induce SNC1 expression. Moreover, glycosylation activity of UGT73C7 resulted in the redirection of phenylpropanoid metabolic flux to biosynthesis of hydroxycinnamic acids and coumarins. The disruption of the phenylpropanoid pathway suppressed UGT73C7-promoted SNC1 expression and the immune response. This study not only identified UGT73C7 as an important regulator that adjusts phenylpropanoid metabolism upon pathogen challenge, but also provided a link between phenylpropanoid metabolism and an NLR gene.


Assuntos
Proteínas de Arabidopsis/imunologia , Arabidopsis/fisiologia , Glicosiltransferases/metabolismo , Imunidade Vegetal/fisiologia , Arabidopsis/efeitos dos fármacos , Proteínas de Arabidopsis/genética , Ácidos Cumáricos/metabolismo , Resistência à Doença/imunologia , Regulação da Expressão Gênica de Plantas , Glicosilação , Glicosiltransferases/genética , Glicosiltransferases/imunologia , Interações Hospedeiro-Patógeno/fisiologia , Ácidos Isonicotínicos/farmacologia , Doenças das Plantas/imunologia , Plantas Geneticamente Modificadas , Pseudomonas syringae/patogenicidade
9.
Molecules ; 26(5)2021 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-33800273

RESUMO

Pseudomonas syringae pv. actinidiae (Psa) is the pathogenic agent responsible for the bacterial canker of kiwifruit (BCK) leading to major losses in kiwifruit productions. No effective treatments and measures have yet been found to control this disease. Despite antimicrobial peptides (AMPs) having been successfully used for the control of several pathogenic bacteria, few studies have focused on the use of AMPs against Psa. In this study, the potential of six AMPs (BP100, RW-BP100, CA-M, 3.1, D4E1, and Dhvar-5) to control Psa was investigated. The minimal inhibitory and bactericidal concentrations (MIC and MBC) were determined and membrane damaging capacity was evaluated by flow cytometry analysis. Among the tested AMPs, the higher inhibitory and bactericidal capacity was observed for BP100 and CA-M with MIC of 3.4 and 3.4-6.2 µM, respectively and MBC 3.4-10 µM for both. Flow cytometry assays suggested a faster membrane permeation for peptide 3.1, in comparison with the other AMPs studied. Peptide mixtures were also tested, disclosing the high efficiency of BP100:3.1 at low concentration to reduce Psa viability. These results highlight the potential interest of AMP mixtures against Psa, and 3.1 as an antimicrobial molecule that can improve other treatments in synergic action.


Assuntos
Proteínas Citotóxicas Formadoras de Poros/farmacologia , Pseudomonas syringae/efeitos dos fármacos , Actinidia , Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Sinergismo Farmacológico , Frutas/efeitos dos fármacos , Histatinas/farmacologia , Oligopeptídeos/farmacologia , Doenças das Plantas/microbiologia , Proteínas Citotóxicas Formadoras de Poros/metabolismo , Pseudomonas syringae/metabolismo , Pseudomonas syringae/patogenicidade
10.
Int J Mol Sci ; 22(8)2021 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-33919557

RESUMO

Bacterial angular leaf spot disease (ALS) caused by Pseudomonas syringae pv. lachrymans (Psl) is one of the biological factors limiting cucumber open-field production. The goal of this study was to characterize cytological and transcriptomic response of cucumber to this pathogen. Plants of two inbred lines, B10 (susceptible) and Gy14 (resistant), were grown, and leaves were inoculated with highly virulent Psl strain 814/98 under growth chamber conditions. Microscopic and transcriptional evaluations were performed at three time points: before, 1 and 3 days post inoculation (dpi). Investigated lines showed distinct response to Psl. At 1 dpi bacterial colonies were surrounded by necrotized mesophyll cells. At 3 dpi, in the susceptible B10 line bacteria were in contact with degraded cells, whereas cells next to bacteria in the resistant Gy14 line were plasmolyzed, but apparently still alive and functional. Additionally, the level of H2O2 production was higher in resistant Gy14 plants than in B10 at both examined time points. In RNA sequencing more than 18,800 transcripts were detected in each sample. As many as 1648 and 2755 differentially expressed genes (DEGs) at 1 dpi as well as 2992 and 3141 DEGs at 3 dpi were identified in B10 and Gy14, respectively. DEGs were characterized in terms of functional categories. Resistant line Gy14 showed massive transcriptomic response to Psl at 1 dpi compared to susceptible line B10, while a similar number of DEGs was detected for both lines at 3 dpi. This suggests that dynamic transcriptomic response to the invading pathogen may be related with host resistance. This manuscript provides the first transcriptomic data on cucumber infected with the pathovar lachrymans and helps to elucidate resistance mechanism against ALS disease.


Assuntos
Cucumis sativus/genética , Cucumis sativus/microbiologia , Perfilação da Expressão Gênica/métodos , Pseudomonas syringae/patogenicidade , Regulação da Expressão Gênica de Plantas , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
11.
Plant Sci ; 305: 110834, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33691968

RESUMO

Priming is a mechanism of defense that prepares the plant's immune system for a faster and/or stronger activation of cellular defenses against future exposure to different types of stress. This enhanced resistance can be achieved by using inorganic and organic compounds which imitate the biological induction of systemic acquired resistance. INA (2,6 dichloro-isonicotinic acid) was the first synthetic compound created as a resistance inducer for plant-pathogen interactions. However, the use of INA to activate primed resistance in common bean, at the seed stage and during germination, remains experimentally unexplored. Here, we test the hypothesis that INA-seed treatment would induce resistance in common bean plants to Pseudomonas syringae pv. phaseolicola, and that the increased resistance is not accompanied by a tradeoff between plant defense and growth. Additionally, it was hypothesized that treating seeds with INA has a transgenerational priming effect. We provide evidence that seed treatment activates a primed state for disease resistance, in which low nucleosome enrichment and reduced histone activation marks during the priming phase, are associated with a defense-resistant phenotype, characterized by symptom appearance, pathogen accumulation, yield, and changes in gene expression. In addition, the priming status for induced resistance can be inherited to its offspring.


Assuntos
Resistência à Doença/imunologia , Germinação/imunologia , Ácidos Isonicotínicos/metabolismo , Phaseolus/imunologia , Phaseolus/metabolismo , Sementes/crescimento & desenvolvimento , Sementes/imunologia , Produtos Agrícolas/imunologia , Produtos Agrícolas/metabolismo , Doenças das Plantas/microbiologia , Pseudomonas syringae/patogenicidade
12.
Nature ; 592(7852): 110-115, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33692545

RESUMO

The plant immune system involves cell-surface receptors that detect intercellular pathogen-derived molecules, and intracellular receptors that activate immunity upon detection of pathogen-secreted effector proteins that act inside the plant cell. Immunity mediated by surface receptors has been extensively studied1, but that mediated by intracellular receptors has rarely been investigated in the absence of surface-receptor-mediated immunity. Furthermore, interactions between these two immune pathways are poorly understood. Here, by activating intracellular receptors without inducing surface-receptor-mediated immunity, we analyse interactions between these two distinct immune systems in Arabidopsis. Pathogen recognition by surface receptors activates multiple protein kinases and NADPH oxidases, and we find that intracellular receptors primarily potentiate the activation of these proteins by increasing their abundance through several mechanisms. Likewise, the hypersensitive response that depends on intracellular receptors is strongly enhanced by the activation of surface receptors. Activation of either immune system alone is insufficient to provide effective resistance against the bacterial pathogen Pseudomonas syringae. Thus, immune pathways activated by cell-surface and intracellular receptors in plants mutually potentiate to activate strong defences against pathogens. These findings reshape our understanding of plant immunity and have broad implications for crop improvement.


Assuntos
Arabidopsis/imunologia , Proteínas NLR/imunologia , Imunidade Vegetal/imunologia , Receptores de Reconhecimento de Padrão/imunologia , Arabidopsis/citologia , Arabidopsis/microbiologia , Morte Celular , NADPH Oxidases/metabolismo , Células Vegetais/imunologia , Células Vegetais/microbiologia , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Proteínas Quinases/metabolismo , Pseudomonas fluorescens/imunologia , Pseudomonas syringae/imunologia , Pseudomonas syringae/patogenicidade , Transdução de Sinais/imunologia
13.
Plant Cell ; 33(6): 2015-2031, 2021 07 19.
Artigo em Inglês | MEDLINE | ID: mdl-33751120

RESUMO

Acquisition of nutrients from different species is necessary for pathogen colonization. Iron is an essential mineral nutrient for nearly all organisms, but little is known about how pathogens manipulate plant hosts to acquire iron. Here, we report that AvrRps4, an effector protein delivered by Pseudomonas syringae bacteria to plants, interacts with and targets the plant iron sensor protein BRUTUS (BTS) to facilitate iron uptake and pathogen proliferation in Arabidopsis thaliana. Infection of rps4 and eds1 by P. syringae pv. tomato (Pst) DC3000 expressing AvrRps4 resulted in iron accumulation, especially in the plant apoplast. AvrRps4 alleviates BTS-mediated degradation of bHLH115 and ILR3(IAA-Leucine resistant 3), two iron regulatory proteins. In addition, BTS is important for accumulating immune proteins Enhanced Disease Susceptibility1 (EDS1) at both the transcriptional and protein levels upon Pst (avrRps4) infections. Our findings suggest that AvrRps4 targets BTS to facilitate iron accumulation and BTS contributes to RPS4/EDS1-mediated immune responses.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/fisiologia , Proteínas de Bactérias/metabolismo , Interações Hospedeiro-Patógeno/fisiologia , Ferro/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/imunologia , Proteínas de Bactérias/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/imunologia , Proteínas de Ligação a DNA/metabolismo , Regulação da Expressão Gênica de Plantas , Mutação , Imunidade Vegetal/genética , Plantas Geneticamente Modificadas , Pseudomonas syringae/metabolismo , Pseudomonas syringae/patogenicidade , Ubiquitina-Proteína Ligases/genética
14.
Plant Physiol ; 185(4): 1986-2002, 2021 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-33564884

RESUMO

Ligand-induced endocytosis of the immune receptor FLAGELLIN SENSING2 (FLS2) is critical for maintaining its proper abundance in the plasma membrane (PM) to initiate and subsequently down regulate cellular immune responses to bacterial flagellin or flg22-peptide. The molecular components governing PM abundance of FLS2, however, remain mostly unknown. Here, we identified Arabidopsis (Arabidopsis thaliana) DYNAMIN-RELATED PROTEIN1A (DRP1A), a member of a plant-specific family of large dynamin GTPases, as a critical contributor to ligand-induced endocytosis of FLS2 and its physiological roles in flg22-signaling and immunity against Pseudomonas syringae pv. tomato DC3000 bacteria in leaves. Notably, drp1a single mutants displayed similar flg22-defects as those previously reported for mutants in another dynamin-related protein, DRP2B, that was previously shown to colocalize with DRP1A. Our study also uncovered synergistic roles of DRP1A and DRP2B in plant growth and development as drp1a drp2b double mutants exhibited severely stunted roots and cotyledons, as well as defective cell shape, cytokinesis, and seedling lethality. Furthermore, drp1a drp2b double mutants hyperaccumulated FLS2 in the PM prior to flg22-treatment and exhibited a block in ligand-induced endocytosis of FLS2, indicating combinatorial roles for DRP1A and DRP1B in governing PM abundance of FLS2. However, the increased steady-state PM accumulation of FLS2 in drp1a drp2b double mutants did not result in increased flg22 responses. We propose that DRP1A and DRP2B are important for the regulation of PM-associated levels of FLS2 necessary to attain signaling competency to initiate distinct flg22 responses, potentially through modulating the lipid environment in defined PM domains.


Assuntos
Arabidopsis/crescimento & desenvolvimento , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Dinaminas/metabolismo , Flagelina/metabolismo , Imunidade Vegetal/fisiologia , Pseudomonas syringae/patogenicidade , Endocitose/efeitos dos fármacos
15.
Plant Cell Environ ; 44(5): 1596-1610, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33547690

RESUMO

Nitrogen (N) influences a myriad of physiological processes while its effects on plant defences and the underlying mechanisms are largely unknown. Here, the interaction between tomato and pathogens was examined under four N regimes (sole NO3 - or mixed NO3 - /NH4 + of total 1 and 7 mM N, denoting low and high N regimes, respectively) followed by inoculation with two bacterial pathogens, Pseudomonas syringae and Ralstonia solanacearum. Tomato immunity against both pathogens was generally higher under low N as well as NO3 - as the sole N source. The disease susceptibility was reduced by silencing N metabolism genes such as NR, NiR and Fd-GOGAT, while increased in NiR1-overexpressed plants. Further studies demonstrated that the N-modulated defence was dependent on the salicylic acid (SA) defence pathway. Low N as well as the silencing of N metabolism genes increased the SA levels and transcripts of its maker genes, and low N-enhanced defence was blocked in NahG transgenic tomato plants that do not accumulate SA, while exogenous SA application attenuated the susceptibility of OE-NiR1. The study provides insights into the mechanisms of how nitrogen fertilization and metabolism affect plant immunity in tomato, which might be useful for designing effective agronomic strategies for the management of N supply.


Assuntos
Lycopersicon esculentum/imunologia , Lycopersicon esculentum/microbiologia , Nitrogênio/metabolismo , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Raízes de Plantas/microbiologia , Ciclopentanos/metabolismo , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Inativação Gênica , Genes de Plantas , Lycopersicon esculentum/genética , Oxilipinas/metabolismo , Doenças das Plantas/genética , Folhas de Planta/genética , Raízes de Plantas/genética , Plantas Geneticamente Modificadas , Pseudomonas syringae/patogenicidade , Pseudomonas syringae/fisiologia , Ralstonia solanacearum/patogenicidade , Ralstonia solanacearum/fisiologia , Ácido Salicílico/metabolismo
16.
Appl Biochem Biotechnol ; 193(5): 1482-1495, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33484446

RESUMO

D-Mannose isomerase can reversibly catalyze D-fructose to D-mannose which has various beneficial effects. A novel D-mannose isomerase gene (PsMIaseA) from Pseudomonas syringae was cloned and expressed in Escherichia coli. The recombinant D-mannose isomerase (PsMIaseA) showed the highest amino acid sequence homogeneity of 50% with ManI from Thermobifda fusca. PsMIaseA was purified through Ni-NTA chromatography, and its specific activity was 818.6 U mg-1. The optimal pH and temperature of PsMIaseA were pH 7.5 and 45 °C, respectively. The enzyme was stable within a wide pH range from 5.0 to 10.0. It could efficiently convert D-fructose to D-mannose without any metal ions. When PsMIaseA was incubated with 600 g/L D-fructose for 6 h, the space-time yield of D-mannose reached 27.2 g L-1 h-1 with a maximum conversion ratio of 27%. Therefore, the D-mannose isomerase may be suitable for green production of D-mannose.


Assuntos
Aldose-Cetose Isomerases/metabolismo , Manose/metabolismo , Pseudomonas syringae/metabolismo , Pseudomonas syringae/patogenicidade , Aldose-Cetose Isomerases/genética , Concentração de Íons de Hidrogênio , Especificidade por Substrato , Temperatura
17.
Mol Genet Genomics ; 296(2): 299-312, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33386986

RESUMO

Pseudomonas syringae pv. tabaci 6605 (Pta6605) is a causal agent of wildfire disease in host tobacco plants and is highly motile. Pta6605 has multiple clusters of chemotaxis genes including cheA, a gene encoding a histidine kinase, cheY, a gene encoding a response regulator, mcp, a gene for a methyl-accepting chemotaxis protein, as well as flagellar and pili biogenesis genes. However, only two major chemotaxis gene clusters, cluster I and cluster II, possess cheA and cheY. Deletion mutants of cheA or cheY were constructed to evaluate their possible role in Pta6605 chemotaxis and virulence. Motility tests and a chemotaxis assay to known attractant demonstrated that cheA2 and cheY2 mutants were unable to swarm and to perform chemotaxis, whereas cheA1 and cheY1 mutants retained chemotaxis ability almost equal to that of the wild-type (WT) strain. Although WT and cheY1 mutants of Pta6605 caused severe disease symptoms on host tobacco leaves, the cheA2 and cheY2 mutants did not, and symptom development with cheA1 depended on the inoculation method. These results indicate that chemotaxis genes located in cluster II are required for optimal chemotaxis and host plant infection by Pta6605 and that cluster I may partially contribute to these phenotypes.


Assuntos
Histidina Quinase/genética , Proteínas Quimiotáticas Aceptoras de Metil/genética , Pseudomonas aeruginosa/fisiologia , Pseudomonas syringae/fisiologia , Tabaco/microbiologia , Quimiotaxia , Resistência à Doença , Deleção de Genes , Histidina Quinase/metabolismo , Proteínas Quimiotáticas Aceptoras de Metil/metabolismo , Família Multigênica , Filogenia , Doenças das Plantas/microbiologia , Pseudomonas aeruginosa/patogenicidade , Pseudomonas syringae/patogenicidade , Virulência
18.
J Exp Bot ; 72(6): 2231-2241, 2021 03 17.
Artigo em Inglês | MEDLINE | ID: mdl-33188427

RESUMO

Iron (Fe) is a poorly available mineral nutrient which affects the outcome of many cross-kingdom interactions. In Arabidopsis thaliana, Fe starvation limits infection by necrotrophic pathogens. Here, we report that Fe deficiency also reduces disease caused by the hemi-biotrophic bacterium Pseudomonas syringae and the biotrophic oomycete Hyaloperonospora arabidopsidis, indicating that Fe deficiency-induced resistance is effective against pathogens with different lifestyles. Furthermore, we show that Fe deficiency-induced resistance is not caused by withholding Fe from the pathogen but is a plant-mediated defense response that requires activity of ethylene and salicylic acid. Because rhizobacteria-induced systemic resistance (ISR) is associated with a transient up-regulation of the Fe deficiency response, we tested whether Fe deficiency-induced resistance and ISR are similarly regulated. However, Fe deficiency-induced resistance functions independently of the ISR regulators MYB72 and BGLU42, indicating that both types of induced resistance are regulated in a different manner. Mutants opt3 and frd1, which display misregulated Fe homeostasis under Fe-sufficient conditions, show disease resistance levels comparable with those of Fe-starved wild-type plants. Our results suggest that disturbance of Fe homeostasis, through Fe starvation stress or other non-homeostatic conditions, is sufficient to prime the plant immune system for enhanced defense.


Assuntos
Proteínas de Arabidopsis , Arabidopsis/microbiologia , Doenças das Plantas/microbiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Resistência à Doença , Regulação da Expressão Gênica de Plantas , Pseudomonas syringae/patogenicidade , Ácido Salicílico
19.
Plant J ; 105(3): 831-840, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33124734

RESUMO

The lengthy process to generate transformed plants is a limitation in current research on the interactions of the model plant pathogen Pseudomonas syringae with plant hosts. Here we present an easy method called agromonas, where we quantify P. syringae growth in agroinfiltrated leaves of Nicotiana benthamiana using a cocktail of antibiotics to select P. syringae on plates. As a proof of concept, we demonstrate that transient expression of PAMP receptors reduces bacterial growth, and that transient depletion of a host immune gene and transient expression of a type-III effector increase P. syringae growth in agromonas assays. We show that we can rapidly achieve structure-function analysis of immune components and test the function of immune hydrolases. The agromonas method is easy, fast and robust for routine disease assays with various Pseudomonas strains without transforming plants or bacteria. The agromonas assay offers a reliable approach for further comprehensive analysis of plant immunity.


Assuntos
Doenças das Plantas/microbiologia , Imunidade Vegetal/genética , Folhas de Planta/microbiologia , Pseudomonas syringae/patogenicidade , Tabaco/microbiologia , Antibacterianos/farmacologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/imunologia , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Doenças das Plantas/imunologia , Plantas Geneticamente Modificadas , Pseudomonas syringae/efeitos dos fármacos , Pseudomonas syringae/crescimento & desenvolvimento , Receptores de Reconhecimento de Padrão/genética , Receptores de Reconhecimento de Padrão/imunologia
20.
Plant J ; 105(5): 1274-1292, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33289145

RESUMO

Pathogens secrete effector proteins into host cells to suppress host immunity and promote pathogen virulence, although many features at the molecular interface of host-pathogen interactions remain to be characterized. In a yeast two-hybrid assay, we found that the Pseudomonas syringae effector HopZ1a interacts with the Arabidopsis transcriptional regulator Abscisic Acid Repressor 1 (ABR1). Further analysis revealed that ABR1 interacts with multiple P. syringae effectors, suggesting that it may be targeted as a susceptibility hub. Indeed, loss-of-function abr1 mutants exhibit reduced susceptibility to a number of P. syringae strains. The ABR1 protein comprises a conserved APETALA2 (AP2) domain flanked by long regions of predicted structural disorder. We verified the DNA-binding activity of the AP2 domain and demonstrated that the disordered domains act redundantly to enhance DNA binding and to facilitate transcriptional activation by ABR1. Finally, we compared gene expression profiles from wild-type and abr1 plants following inoculation with P. syringae, which suggested that the reduced susceptibility of abr1 mutants is due to the loss of a virulence target rather than an enhanced immune response. These data highlight ABR1 as a functionally important component at the host-pathogen interface.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/metabolismo , Fatores de Transcrição/metabolismo , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Pseudomonas syringae/patogenicidade , Fatores de Transcrição/genética , Virulência , Fatores de Virulência
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