Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 683
Filtrar
1.
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
2.
J Vis Exp ; (157)2020 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-32225144

RESUMO

Tomato is an agronomically important crop that can be infected by Pseudomonas syringae, a Gram-negative bacterium, resulting in bacterial speck disease. The tomato-P. syringae pv. tomato pathosystem is widely used to dissect the genetic basis of plant innate responses and disease resistance. While disease was successfully managed for many decades through the introduction of the Pto/Prf gene cluster from Solanum pimpinellifolium into cultivated tomato, race 1 strains of P. syringae have evolved to overcome resistance conferred by the Pto/Prf gene cluster and occur worldwide. Wild tomato species are important reservoirs of natural diversity in pathogen recognition, because they evolved in diverse environments with different pathogen pressures. In typical screens for disease resistance in wild tomato, adult plants are used, which can limit the number of plants that can be screened due to their extended growth time and greater growth space requirements. We developed a method to screen 10-day-old tomato seedlings for resistance, which minimizes plant growth time and growth chamber space, allows a rapid turnover of plants, and allows large sample sizes to be tested. Seedling outcomes of survival or death can be treated as discrete phenotypes or on a resistance scale defined by amount of new growth in surviving seedlings after flooding. This method has been optimized to screen 10-day-old tomato seedlings for resistance to two P. syringae strains and can easily be adapted to other P. syringae strains.


Assuntos
Bioensaio/métodos , Resistência à Doença , Lycopersicon esculentum/microbiologia , Doenças das Plantas/microbiologia , Pseudomonas syringae/fisiologia , Plântula/microbiologia , Cotilédone/fisiologia , Meios de Cultura , Ecótipo , Lycopersicon esculentum/genética , Lycopersicon esculentum/crescimento & desenvolvimento , Fenótipo , Esterilização
3.
Plant Physiol Biochem ; 149: 301-312, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32120172

RESUMO

Chitosan oligosaccharides (COS) worked effectively in multiple plant-pathogen interactions as plant immunity regulator, however, due to the complexity of the COS-induced immune signaling network, the topic requires further investigation. In the present study, quantitative analysis of proteins was performed to investigate the underlying mechanism of COS induced resistance to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) in Arabidopsis thaliana. 4303 proteins were successfully quantified, 186, 217 and 207 proteins were differently regulated in mock + Pst, COS, and COS + Pst treated plants, respectively, compared with mock plants. From detailed functional and hierarchical clustering analysis, a priming effect of COS on plant immune system by pre-regulated the key proteins related to signaling transduction, defense response, cell wall biosynthesis and modification, plant growth and development, gene transcription and translation, which confers enhanced resistance when Pst DC3000 infection in Arabidopsis. Moreover, RACK1B which has the potential to be the key kinase receptor for COS signals was found out by protein-protein interaction network analysis of COS responsive proteins. In conclusion, COS treatment enable plant to fine-tuning its defense mechanisms for a more rapid and stronger response to future pathogen attacks, which obviously enhances plants defensive capacity that makes COS worked effectively in multiple plant-pathogen interactions.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Quitosana , Resistência à Doença , Arabidopsis/efeitos dos fármacos , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Quitosana/farmacologia , Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Proteômica , Pseudomonas syringae/fisiologia
4.
Plant Sci ; 292: 110372, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32005378

RESUMO

Polyamines (PAs) are small aliphatic amines with important regulatory activities in plants. Biotic stress results in changes in PA levels due to de novo synthesis and PA oxidation. In Arabidopsis thaliana five FAD-dependent polyamine oxidase enzymes (AtPAO1-5) participate in PA back-conversion and degradation. PAO activity generates H2O2, an important molecule involved in cell signaling, elongation, programmed cell death, and defense responses. In this work we analyzed the role of AtPAO genes in the Arabidopsis thaliana-Pseudomonas syringae pathosystem. AtPAO1 and AtPAO2 genes were transcriptionally up-regulated in infected plants. Atpao1-1 and Atpao2-1 single mutant lines displayed altered responses to Pseudomonas, and an increased susceptibility was found in the double mutant Atpao1-1 x Atpao2-1. These polyamine oxidases mutant lines showed disturbed contents of ROS (H2O2 and O2-) and altered activities of RBOH, CAT and SOD enzymes both in infected and control plants. In addition, changes in the expression levels of AtRBOHD, AtRBOHF, AtPRX33, and AtPRX34 genes were also noticed. Our data indicate an important role for polyamine oxidases in plant defense and ROS homeostasis.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/fisiologia , Regulação da Expressão Gênica de Plantas , NADPH Oxidases/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Oxirredutases atuantes sobre Doadores de Grupo CH-NH2/genética , Pseudomonas syringae/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Arabidopsis/enzimologia , Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , NADPH Oxidases/metabolismo , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/metabolismo , Oxirredutases atuantes sobre Doadores de Grupo CH-NH2/metabolismo
5.
Plant Sci ; 292: 110386, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32005391

RESUMO

The plasma membrane (PM)-localized receptor-like kinases (RLKs) play important roles in pathogen defense. One of the first cloned RLKs is the Arabidopsis receptor kinase FLAGELLIN SENSING 2 (FLS2), which specifically recognizes a conserved 22 amino acid N-terminal sequence of Pseudomonas syringae pv.tomato DC3000 (Pst) flagellin protein (flg22). Although extensively studied in Arabidopsis, the functions of RLKs in crop plants remain largely uninvestigated. To understand the roles of RLKs in soybean (Glycine max), GmFLS2 was silenced via virus induced gene silencing (VIGS) mediated by Bean pod mottle virus (BPMV). No significant morphological differences were observed between GmFLS2-silenced plants and the vector control plants. However, silencing GmFLS2 significantly enhanced the susceptibility of the soybean plants to Pseudomonas syringae pv.glycinea (Psg). Kinase activity assay showed that silencing GmFLS2 significantly reduced the phosphorylation level of GmMPK6 in response to flg22 treatment. However, reduced phosphorylation level of both GmMPK3 and GmMPK6 in response to Psg infection was observed in GmFLS2-silenced plants, implying that defense response is likely transduced through activation of the downstream GmMAPK signaling pathway upon recognition of bacterial pathogen by GmFLS2. The core peptides of flg22 from Pst and Psg were highly conserved and only 4 amino acid differences were seen at their N-termini. Interestingly, it appeared that the Psg-flg22 was more effective in activating soybean MAPKs than activating Arabidopsis MAPKs, and conversely, Pst-flg22 was more effective in activating Arabidopsis MAPKs than activating soybean MAPKs, suggesting that the cognate recognition is more potent than heterologous recognition in activating downstream signaling. Taken together, our results suggest that the function of FLS2 is conserved in immunity against bacteria pathogens across different plant species.


Assuntos
Inativação Gênica , Doenças das Plantas/genética , Proteínas de Plantas/genética , Proteínas Quinases/genética , Pseudomonas syringae/fisiologia , Soja/genética , Soja/microbiologia , Comovirus , Doenças das Plantas/microbiologia , Proteínas de Plantas/metabolismo , Proteínas Quinases/metabolismo
6.
Microb Ecol ; 80(1): 81-102, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31897570

RESUMO

Since 2008, the kiwifruit industry has been devastated by a pandemic outbreak of Pseudomonas syringae pv. actinidiae (Psa), the causal agent of bacterial canker. This disease has become the most significant limiting factor in kiwifruit production. Psa colonizes different organs of the host plant, causing a specific symptomatology on each of them. In addition, the systemic invasion of the plant may quickly lead to plant death. Despite the massive risk that this disease poses to the kiwifruit industry, studies focusing on Psa ecology have been sporadic, and a comprehensive description of the disease epidemiology is still missing. Optimal environmental conditions for infection, dispersal and survival in the environment, or the mechanisms of penetration and colonization of host tissues have not been fully elucidated yet. The present work aims to provide a synthesis of the current knowledge, and a deeper understanding of the epidemiology of kiwifruit bacterial canker based on new experimental data. The pathogen may survive in the environment or overwinter in dormant tissues and be dispersed by wind or rain. Psa was observed in association with several plant structures (stomata, trichomes, lenticels) and wounds, which could represent entry points for apoplast infection. Environmental conditions also affect the bacterial colonization, with lower optimum values of temperature and humidity for epiphytic than for endophytic growth, and disease incidence requiring a combination of mild temperature and leaf wetness. By providing information on Psa ecology, these data sets may contribute to plan efficient control strategies for kiwifruit bacterial canker.


Assuntos
Actinidia/fisiologia , Doenças das Plantas/microbiologia , Pseudomonas syringae/fisiologia , Folhas de Planta/microbiologia , Folhas de Planta/fisiologia
7.
PLoS One ; 15(1): e0227559, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31910230

RESUMO

A multiplex real-time PCR method based on fluorescent TaqMan® probes was developed for the simultaneous detection of the tomato pathogenic bacteria Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. tomato and bacterial spot-causing xanthomonads. The specificity of the multiplex assay was validated on 44 bacterial strains, including 32 target pathogen strains as well as closely related species and nontarget tomato pathogenic bacteria. The designed multiplex real-time PCR showed high sensitivity when positive amplification was observed for one pg of bacterial DNA in the cases of Clavibacter michiganensis subsp. michiganensis and Pseudomonas syringae pv. tomato bacteria and 100 pg for bacterial spot-causing xanthomonads. The reliability of the developed multiplex real-time PCR assay for in planta detection was verified by recognition of the target pathogens in 18 tomato plants artificially inoculated by each of the target bacteria and tomato samples from production greenhouses.


Assuntos
Actinobacteria/isolamento & purificação , Lycopersicon esculentum/microbiologia , Pseudomonas syringae/isolamento & purificação , Reação em Cadeia da Polimerase em Tempo Real , Xanthomonas/isolamento & purificação , Actinobacteria/genética , Actinobacteria/fisiologia , Ambiente Controlado , Lycopersicon esculentum/crescimento & desenvolvimento , Pseudomonas syringae/genética , Pseudomonas syringae/fisiologia , Xanthomonas/genética , Xanthomonas/fisiologia
8.
J Med Microbiol ; 69(3): 478-486, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31935181

RESUMO

Introduction. Pseudomonas syringae pv. actinidiae (Psa) has emerged as a major bacterial pathogen of kiwifruit cultivation throughout the world.Aim. We aim to introduce a CRISPR-Cas9 system, a commonly used genome editing tool, into Psa. The protocols may also be useful in other Pseudomonas species.Methodology. Using standard molecular biology techniques, we modified plasmid pCas9, which carries the CRISPR-Cas9 sequences from Streptococcus pyogenes, for use in Psa. The final plasmid, pJH1, was produced in a series of steps and is maintained with selection in both Escherichia coli and Psa.Results. We have constructed plasmids carrying a CRISPR-Cas9 system based on that of S. pyogenes, which can be maintained, under selection, in Psa. We have shown that the gene targeting capacity of the CRISPR-Cas9 system is active and that the Cas9 protein is able to cleave the targeted sites. The Cas9 was directed to several different sites in the P. syringae genome. Using Cas9 we have generated Psa transformants that no longer carry the native plasmid present in Psa, and other transformants that lack the integrative, conjugative element, Pac_ICE1. Targeting of a specific gene, a chromosomal non-ribosomal peptide synthetase, led to gene knockouts with the transformants having deletions encompassing the target site.Conclusion. We have constructed shuttle plasmids carrying a CRISPR-Cas9 system that are maintained in both E. coli and P. syringae pv. actinidiae. We have used this gene editing system to eliminate features of the accessory genome (plasmids or ICEs) from Psa and to target a single chromosomal gene.


Assuntos
Sistemas CRISPR-Cas/fisiologia , Pseudomonas syringae/fisiologia , Actinidia/microbiologia , Sistemas CRISPR-Cas/genética , Escherichia coli/fisiologia , Frutas/microbiologia , Deleção de Genes , Técnicas de Inativação de Genes , Marcação de Genes , Engenharia Genética , Peptídeo Sintases/genética , Plasmídeos , Pseudomonas syringae/genética , Análise de Sequência de DNA , Streptococcus pyogenes/fisiologia , Sequenciamento Completo do Genoma
9.
Plant Sci ; 291: 110361, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31928670

RESUMO

Light modulates almost every aspect of plant physiology, including plant-pathogen interactions. Among these, the hypersensitive response (HR) of plants to pathogens is characterized by a rapid and localized programmed cell death (PCD), which is critical to restrict the spread of pathogens from the infection site. The aim of this work was to study the role of light in the interaction between Pseudomonas syringae pv. tomato DC3000 (Pto DC3000) and non-host tobacco plants. To this end, we examined the HR under different light treatments (white and red light) by using a range of well-established markers of PCD. The alterations found at the cellular level included: i) loss of membrane integrity and nuclei, ii) RuBisCo and DNA degradation, and iii) changes in nuclease profiles and accumulation of cysteine proteinases. Our results suggest that red light plays a role during the HR of tobacco plants to Pto DC3000 infection, delaying the PCD process.


Assuntos
Apoptose/efeitos da radiação , Interações Hospedeiro-Patógeno/efeitos da radiação , Luz , Pseudomonas syringae/fisiologia , Tabaco/fisiologia , Doenças das Plantas/microbiologia , Tabaco/microbiologia , Tabaco/efeitos da radiação
10.
Plant Biol (Stuttg) ; 22(2): 309-316, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31758615

RESUMO

Plant immunity is regulated by a huge phytohormone regulation network. Ethylene(ET) and brassinosteroids (BRs) play critical roles in plant response to biotic stress; however, the relationship between BR and ET in plant immunity is unclear. We used chemical treatments, genetic approaches and inoculation experiments to investigate the relationship between ET and BR in plant defense against Pst DC3000 in Nicotiana benthamiana. Foliar applications of ET and BR enhanced plant resistance to Pst DC3000 inoculation, while treatment with brassinazole (BRZ, a specific BR biosynthesis inhibitor) eliminated the ET induced plant resistance to Pst DC3000. Silencing of DWARF 4(DWF4, a key BR biosynthetic gene), BRASSINOSTEROID INSENSITIVE 1 (BRI1, aBR receptor) and BRASSINOSTEROID-SIGNALING KINASE 1 (BSK1, downstream of BRI1) also neutralised the ET-induced plant resistance to Pst DC3000. ET can induce callose deposition and reactive oxygen species (ROS) accumulation to resistPst DC3000, BRZ-treated and gene-silenced were completely eliminate this response. Our results suggest BR is involved in ET-induced plant resistance, the involvement of ET in plant resistance is possibly by the induction of callose deposition and ROS accumulation, in a BR-dependent manner.


Assuntos
Brassinosteroides , Resistência à Doença , Etilenos , Tabaco , Brassinosteroides/farmacologia , Resistência à Doença/efeitos dos fármacos , Etilenos/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Proteínas de Plantas , Pseudomonas syringae/fisiologia , Tabaco/efeitos dos fármacos , Tabaco/microbiologia
11.
J Gen Virol ; 101(1): 122-135, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31730035

RESUMO

Plants are simultaneously exposed to a variety of biotic and abiotic stresses, such as infections by viruses and bacteria, or drought. This study aimed to improve our understanding of interactions between viral and bacterial pathogens and the environment in the incompatible host Nicotiana benthamiana and the susceptible host Arabidopsis thaliana, and the contribution of viral virulence proteins to these responses. Infection by the P otato virus X (PVX)/P lum pox virus (PPV) pathosystem induced resistance to Pseudomonas syringae (Pst) and to drought in both compatible and incompatible bacteria-host interactions, once a threshold level of defence responses was triggered by the virulence proteins P25 of PVX and the helper component proteinase of PPV. Virus-induced resistance to Pst was compromised in salicylic acid and jasmonic acid signalling-deficient Arabidopsis but not in N. benthamiana lines. Elevated temperature and CO2 levels, parameters associated with climate change, negatively affected resistance to Pst and to drought induced by virus infection, and this correlated with diminished H2O2 production, decreased expression of defence genes and a drop in virus titres. Thus, diminished virulence should be considered as a potential factor limiting the outcome of beneficial trade-offs in the response of virus-infected plants to drought or bacterial pathogens under a climate change scenario.


Assuntos
Dióxido de Carbono/metabolismo , Interações entre Hospedeiro e Microrganismos/fisiologia , Doenças das Plantas/microbiologia , Doenças das Plantas/virologia , Pseudomonas syringae/fisiologia , Pseudomonas syringae/virologia , Arabidopsis/microbiologia , Arabidopsis/virologia , Ciclopentanos/metabolismo , Secas , Regulação da Expressão Gênica de Plantas/fisiologia , Peróxido de Hidrogênio/metabolismo , Oxilipinas/metabolismo , Ácido Salicílico/metabolismo , Temperatura , Virulência/fisiologia
12.
J Bacteriol ; 202(4)2020 01 29.
Artigo em Inglês | MEDLINE | ID: mdl-31740494

RESUMO

Flagella power bacterial movement through liquids and over surfaces to access or avoid certain environmental conditions, ultimately increasing a cell's probability of survival and reproduction. In some cases, flagella and chemotaxis are key virulence factors enabling pathogens to gain entry and attach to suitable host tissues. However, flagella are not always beneficial; both plant and animal immune systems have evolved receptors to sense the proteins that make up flagellar filaments as signatures of bacterial infection. Microbes poorly adapted to avoid or counteract these immune functions are unlikely to be successful in host environments, and this selective pressure has driven the evolution of diverse and often redundant pathogen compensatory mechanisms. We tested the role of AlgU, the Pseudomonas extracytoplasmic function sigma factor σE/σ22 ortholog, in regulating flagellar expression in the context of Pseudomonas syringae-plant interactions. We found that AlgU is necessary for downregulating bacterial flagellin expression in planta and that this results in a corresponding reduction in plant immune elicitation. This AlgU-dependent regulation of flagellin gene expression is beneficial to bacterial growth in the course of plant infection, and eliminating the plant's ability to detect flagellin makes this AlgU-dependent function irrelevant for bacteria growing in the apoplast. Together, these results add support to an emerging model in which P. syringae AlgU functions at a key control point that serves to optimize the expression of bacterial functions during host interactions, including minimizing the expression of immune elicitors and concomitantly upregulating beneficial virulence functions.IMPORTANCE Foliar plant pathogens, like Pseudomonas syringae, adjust their physiology and behavior to facilitate host colonization and disease, but the full extent of these adaptations is not known. Plant immune systems are triggered by bacterial molecules, such as the proteins that make up flagellar filaments. In this study, we found that during plant infection, AlgU, a gene expression regulator that is responsive to external stimuli, downregulates expression of fliC, which encodes the flagellin protein, a strong elicitor of plant immune systems. This change in gene expression and resultant change in behavior correlate with reduced plant immune activation and improved P. syringae plant colonization. The results of this study demonstrate the proximate and ultimate causes of flagellar regulation in a plant-pathogen interaction.


Assuntos
Proteínas de Bactérias/fisiologia , Flagelina/genética , Regulação Bacteriana da Expressão Gênica , Imunidade Vegetal , Pseudomonas syringae/fisiologia , Fator sigma/fisiologia , Regulação para Baixo
13.
Plant Sci ; 290: 110328, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31779895

RESUMO

Inoculating a virulent strain of Pseudomonas syringae pv. phaseolicola (Pph) into the leaf of common bean (Phaseolus vulgaris) causes the leaf apoplast to alkalinize. Whether or not this apoplastic pH event facilitates virulence of Pph in interaction with common bean is unclear. For elucidating this topic, (i) Pph colonization of the common bean leaf apoplast, (ii) the formation of bacterial lesions, and (iii) apoplastic sucrose concentration were investigated in relation to the apoplastic leaf pH. For this, the Pph-induced leaf apoplastic alkalinization was attenuated by spray application of either a synthetic auxin or an acidic pH buffer. Apoplastic pH was quantified in planta via microscopy-based pH imaging. Apoplastic washing fluids were extracted to quantify both colonization of bacteria in leaf apoplast and the concentration of apoplastic sucrose. Results reveal that the apoplastic alkalinization facilitated bacterial colonization of the apoplast. Number of colony forming units and area of bacterial lesions were reduced when Pph-induced apoplastic alkalinization was attenuated by foliar application of a synthetic auxin or acidic pH buffer. Application of both agents attenuated the Pph-induced increase of sucrose in the leaf apoplast, which is nutrient for bacteria. Data demonstrate that the Pph-mediated leaf apoplastic alkalinisation favours bacterial colonization.


Assuntos
Phaseolus/microbiologia , Doenças das Plantas/microbiologia , Folhas de Planta/química , Pseudomonas syringae/fisiologia , Interações Hospedeiro-Patógeno , Concentração de Íons de Hidrogênio , Folhas de Planta/microbiologia
14.
Nat Commun ; 10(1): 5571, 2019 12 05.
Artigo em Inglês | MEDLINE | ID: mdl-31804478

RESUMO

Chloroplasts are important for photosynthesis and for plant immunity against microbial pathogens. Here we identify a haustorium-specific protein (Pst_12806) from the wheat stripe rust fungus, Puccinia striiformis f. sp. tritici (Pst), that is translocated into chloroplasts and affects chloroplast function. Transient expression of Pst_12806 inhibits BAX-induced cell death in tobacco plants and reduces Pseudomonas-induced hypersensitive response in wheat. It suppresses plant basal immunity by reducing callose deposition and the expression of defense-related genes. Pst_12806 is upregulated during infection, and its knockdown (by host-induced gene silencing) reduces Pst growth and development, likely due to increased ROS accumulation. Pst_12806 interacts with the C-terminal Rieske domain of the wheat TaISP protein (a putative component of the cytochrome b6-f complex). Expression of Pst_12806 in plants reduces electron transport rate, photosynthesis, and production of chloroplast-derived ROS. Silencing TaISP by virus-induced gene silencing in a susceptible wheat cultivar reduces fungal growth and uredinium development, suggesting an increase in resistance against Pst infection.


Assuntos
Basidiomycota/metabolismo , Cloroplastos/metabolismo , Proteínas Fúngicas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Basidiomycota/genética , Basidiomycota/imunologia , Cloroplastos/imunologia , Cloroplastos/microbiologia , Resistência à Doença/genética , Resistência à Doença/imunologia , Proteínas Fúngicas/genética , Proteínas Fúngicas/imunologia , Regulação Fúngica da Expressão Gênica/imunologia , Inativação Gênica , Glucanos/imunologia , Glucanos/metabolismo , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Doenças das Plantas/genética , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Imunidade Vegetal/genética , Imunidade Vegetal/imunologia , Folhas de Planta/genética , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Ligação Proteica , Pseudomonas syringae/imunologia , Pseudomonas syringae/fisiologia , Espécies Reativas de Oxigênio/imunologia , Triticum/genética , Triticum/microbiologia
15.
Nat Commun ; 10(1): 4996, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31676803

RESUMO

Plants deploy various immune receptors to recognize pathogens and defend themselves. Crosstalk may happen among receptor-mediated signal transduction pathways in the same host during simultaneous infection of different pathogens. However, the related function of the receptor-like kinases (RLKs) in thwarting different pathogens remains elusive. Here, we report that NIK1, which positively regulates plant antiviral immunity, acts as an important negative regulator of antibacterial immunity. nik1 plants exhibit dwarfed morphology, enhanced disease resistance to bacteria and increased PAMP-triggered immunity (PTI) responses, which are restored by NIK1 reintroduction. Additionally, NIK1 negatively regulates the formation of the FLS2/BAK1 complex. The interaction between NIK1 and FLS2/BAK1 is enhanced upon flg22 perception, revealing a novel PTI regulatory mechanism by an RLK. Furthermore, flg22 perception induces NIK1 and RPL10A phosphorylation in vivo, activating antiviral signalling. The NIK1-mediated inverse modulation of antiviral and antibacterial immunity may allow bacteria and viruses to activate host immune responses against each other.


Assuntos
Proteínas de Arabidopsis/genética , Arabidopsis/genética , Imunidade Vegetal/genética , Proteínas Quinases/genética , Proteínas Serina-Treonina Quinases/genética , Arabidopsis/microbiologia , Arabidopsis/virologia , Proteínas de Arabidopsis/imunologia , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/imunologia , Interações Hospedeiro-Patógeno/imunologia , Complexos Multiproteicos/imunologia , Complexos Multiproteicos/metabolismo , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Doenças das Plantas/virologia , Imunidade Vegetal/imunologia , Vírus de Plantas/imunologia , Vírus de Plantas/fisiologia , Plantas Geneticamente Modificadas , Ligação Proteica , Proteínas Quinases/imunologia , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/imunologia , Proteínas Serina-Treonina Quinases/metabolismo , Pseudomonas syringae/imunologia , Pseudomonas syringae/fisiologia , Transdução de Sinais/genética , Transdução de Sinais/imunologia
16.
Nat Commun ; 10(1): 4810, 2019 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-31641112

RESUMO

Systemic acquired resistance (SAR) is a long-lasting broad-spectrum plant immunity induced by mobile signals produced in the local leaves where the initial infection occurs. Although multiple structurally unrelated signals have been proposed, the mechanisms responsible for perception of these signals in the systemic leaves are unknown. Here, we show that exogenously applied nicotinamide adenine dinucleotide (NAD+) moves systemically and induces systemic immunity. We demonstrate that the lectin receptor kinase (LecRK), LecRK-VI.2, is a potential receptor for extracellular NAD+ (eNAD+) and NAD+ phosphate (eNADP+) and plays a central role in biological induction of SAR. LecRK-VI.2 constitutively associates with BRASSINOSTEROID INSENSITIVE1-ASSOCIATED KINASE1 (BAK1) in vivo. Furthermore, BAK1 and its homolog BAK1-LIKE1 are required for eNAD(P)+ signaling and SAR, and the kinase activities of LecR-VI.2 and BAK1 are indispensable to their function in SAR. Our results indicate that eNAD+ is a putative mobile signal, which triggers SAR through its receptor complex LecRK-VI.2/BAK1 in Arabidopsis thaliana.


Assuntos
Proteínas de Arabidopsis/imunologia , Arabidopsis/imunologia , NAD/imunologia , Doenças das Plantas/imunologia , Proteínas Serina-Treonina Quinases/imunologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Resistência à Doença , Regulação da Expressão Gênica de Plantas , Doenças das Plantas/microbiologia , Imunidade Vegetal , Ligação Proteica , Proteínas Serina-Treonina Quinases/genética , Pseudomonas syringae/fisiologia
17.
J Agric Food Chem ; 67(45): 12590-12598, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31639305

RESUMO

Carotenoids play key roles in photosynthesis and photoprotection. Few multicellular plants produce the ketocarotenoid astaxanthin, a strong antioxidant; however, Arabidopsis thaliana lines overexpressing the Chlamydomonas reinhardtii ß-carotene ketolase (CrBKT) accumulated high amounts of astaxanthin in the leaves. In this study, we investigated the changed regulation of key metabolic pathways and the tolerance of the engineered plants to biotic and abiotic stresses resulting from the heterologous expression of CrBKT. Transcriptome analysis identified 1633 and 1722 genes that were differentially expressed in the leaves and siliques, respectively, of CrBKT-overexpressing plants (line CR5) as compared to wild-type Arabidopsis. These genes were enriched in the carotenoid biosynthetic pathways, and plant hormone biosynthesis and signaling pathways. In particular, metabolic profiling showed that, as compared to the wild-type leaves and siliques, overexpression of CrBKT increased the levels of most amino acids, but decreased the contents of sugars and carbohydrates. Furthermore, CR5 plants had lower sensitivity to abscisic acid (ABA) and increased tolerance to oxidative stress. CR5 plants also exhibited enhanced resistance to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000. Our study provides insight into the regulation of carotenoids and the related pathways, which may be involved in plant response to oxidative stress and pathogen infection.


Assuntos
Arabidopsis/genética , Arabidopsis/metabolismo , Doenças das Plantas/microbiologia , Plantas Geneticamente Modificadas/metabolismo , Ácido Abscísico/metabolismo , Arabidopsis/química , Arabidopsis/microbiologia , Regulação da Expressão Gênica de Plantas , Estresse Oxidativo , Doenças das Plantas/genética , Reguladores de Crescimento de Planta/metabolismo , Plantas Geneticamente Modificadas/química , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/microbiologia , Pseudomonas syringae/fisiologia , Xantofilas/biossíntese
18.
Proc Natl Acad Sci U S A ; 116(38): 18900-18910, 2019 09 17.
Artigo em Inglês | MEDLINE | ID: mdl-31484768

RESUMO

The foliar plant pathogen Pseudomonas syringae can establish large epiphytic populations on leaf surfaces before apoplastic colonization. However, the bacterial genes that contribute to these lifestyles have not been completely defined. The fitness contributions of 4,296 genes in P. syringae pv. syringae B728a were determined by genome-wide fitness profiling with a randomly barcoded transposon mutant library that was grown on the leaf surface and in the apoplast of the susceptible plant Phaseolus vulgaris Genes within the functional categories of amino acid and polysaccharide (including alginate) biosynthesis contributed most to fitness both on the leaf surface (epiphytic) and in the leaf interior (apoplast), while genes involved in type III secretion system and syringomycin synthesis were primarily important in the apoplast. Numerous other genes that had not been previously associated with in planta growth were also required for maximum epiphytic or apoplastic fitness. Fourteen hypothetical proteins and uncategorized glycosyltransferases were also required for maximum competitive fitness in and on leaves. For most genes, no relationship was seen between fitness in planta and either the magnitude of their expression in planta or degree of induction in planta compared to in vitro conditions measured in other studies. A lack of association of gene expression and fitness has important implications for the interpretation of transcriptional information and our broad understanding of plant-microbe interactions.


Assuntos
Genes Bacterianos , Interações Hospedeiro-Patógeno/genética , Folhas de Planta/microbiologia , Pseudomonas syringae/fisiologia , Espaço Extracelular/microbiologia , Perfilação da Expressão Gênica , Aptidão Genética , Genoma Bacteriano/genética , Mutação , Doenças das Plantas/microbiologia , Folhas de Planta/citologia , Pseudomonas syringae/genética
19.
Appl Environ Microbiol ; 85(18)2019 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-31285194

RESUMO

The epiphytic bacterium Pseudomonas syringae strain B728a produces the biosurfactant syringafactin, which is hygroscopic. The water-absorbing potential of syringafactin is high. Syringafactin attracts 250% of its weight in water at high relative humidities but is less hygroscopic at lower relative humidities. This finding suggests that the benefit of syringafactin to the producing cells is strongly context dependent. The contribution of syringafactin to the water availability around cells on different matrices was assessed by examining the water stress exhibited by biosensor strains expressing gfp via the water-stress-activated proU promoter. Wild-type cells exhibited significantly less green fluorescent protein (GFP) fluorescence than a syringafactin-deficient strain on dry filters in atmospheres of high water saturation, as well as on leaf surfaces, indicating greater water availability. When infiltrated into the leaf apoplast, wild-type cells also subsequently exhibited less GFP fluorescence than the syringafactin-deficient strain. These results suggest that the apoplast is a dry but humid environment and that, just as on dry but humid leaf surfaces, syringafactin increases liquid water availability and reduces the water stress experienced by P. syringae IMPORTANCE Many microorganisms, including the plant pathogen Pseudomonas syringae, produce amphiphilic compounds known as biosurfactants. While biosurfactants are known to disperse hydrophobic compounds and to reduce water tension, they have other properties that can benefit the cells that produce them. Leaf-colonizing bacteria experience frequent water stress, since liquid water is present only transiently on or in leaf sites that they colonize. The demonstration that syringafactin, a biosurfactant produced by P. syringae, is sufficiently hygroscopic to increase water availability to cells, thus relieving water stress, reveals that P. syringae can modify its local habitat both on leaf surfaces and in the leaf apoplast. Such habitat modification may be a common role for biosurfactants produced by other bacterial species that colonize habitats (such as soil) that are not always water saturated.


Assuntos
Higroscópicos/metabolismo , Folhas de Planta/metabolismo , Pseudomonas syringae/fisiologia , Tensoativos/metabolismo , Água/metabolismo , Interações Hidrofóbicas e Hidrofílicas , Phaseolus/microbiologia , Folhas de Planta/microbiologia , Molhabilidade
20.
Plant Mol Biol ; 101(1-2): 149-162, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31267255

RESUMO

KEY MESSAGE: Here we describe that the regulation of MdWRKY31 on MdHIR4 in transcription and translation levels associated with disease in apple. The phytohormone salicylic acid (SA) is a main factor in apple (Malus domestica) production due to its function in disease resistance. WRKY transcription factors play a vital role in response to stress. An RNA-seq analysis was conducted with 'Royal Gala' seedlings treated with SA to identify the WRKY regulatory mechanism of disease resistance in apple. The analysis indicated that MdWRKY31 was induced. A quantitative real-time polymerase chain reaction (qPCR) analysis demonstrated that the expression of MdWRKY31 was induced by SA and flg22. Ectopic expression of MdWRKY31 in Arabidopsis and Nicotiana benthamiana increased the resistance to flg22 and Pseudomonas syringae tomato (Pst DC3000). A yeast two-hybrid screen was conducted to further analyze the function of MdWRKY31. As a result, hypersensitive-induced reaction (HIR) protein MdHIR4 interacted with MdWRKY31. Biomolecular fluorescence complementation, yeast two-hybrid, and pull-down assays demonstrated the interaction. In our previous study, MdHIR4 conferred decreased resistance to Botryosphaeria dothidea (B. dothidea). A viral vector-based transformation assay indicated that MdWRKY31 evaluated the transcription of SA-related genes, including MdPR1, MdPR5, and MdNPR1 in an MdHIR4-dependent way. A GUS analysis demonstrated that the w-box, particularly w-box2, of the MdHIR4 promoter played a major role in the responses to SA and B. dothidea. Electrophoretic mobility shift assays, yeast one-hybrid assay, and chromatin immunoprecipitation-qPCR demonstrated that MdWRKY31 directly bound to the w-box2 motif in the MdHIR4 promoter. GUS staining activity and a protein intensity analysis further showed that MdWRKY31 repressed MdHIR4 expression. Taken together, our findings reveal that MdWRKY31 regulated plant resistance to B. dothidea through the SA signaling pathway by interacting with MdHIR4.


Assuntos
Resistência à Doença , Malus/genética , Doenças das Plantas/imunologia , Reguladores de Crescimento de Planta/farmacologia , Proteínas de Plantas/metabolismo , Ácido Salicílico/farmacologia , Arabidopsis/genética , Arabidopsis/imunologia , Arabidopsis/microbiologia , Ascomicetos/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Frutas/genética , Frutas/imunologia , Frutas/microbiologia , Regulação da Expressão Gênica de Plantas , Genes Reporter , Malus/imunologia , Malus/microbiologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Regiões Promotoras Genéticas/genética , Pseudomonas syringae/fisiologia , Plântula/genética , Plântula/imunologia , Plântula/microbiologia , Transdução de Sinais , Tabaco/genética , Tabaco/imunologia , Tabaco/microbiologia , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Técnicas do Sistema de Duplo-Híbrido
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...