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1.
PLoS Pathog ; 16(8): e1008835, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32785253

RESUMO

Hyaloperonospora arabidopsidis (Hpa) is an oomycete pathogen causing Arabidopsis downy mildew. Effector proteins secreted from the pathogen into the plant play key roles in promoting infection by suppressing plant immunity and manipulating the host to the pathogen's advantage. One class of oomycete effectors share a conserved 'RxLR' motif critical for their translocation into the host cell. Here we characterize the interaction between an RxLR effector, HaRxL21 (RxL21), and the Arabidopsis transcriptional co-repressor Topless (TPL). We establish that RxL21 and TPL interact via an EAR motif at the C-terminus of the effector, mimicking the host plant mechanism for recruiting TPL to sites of transcriptional repression. We show that this motif, and hence interaction with TPL, is necessary for the virulence function of the effector. Furthermore, we provide evidence that RxL21 uses the interaction with TPL, and its close relative TPL-related 1, to repress plant immunity and enhance host susceptibility to both biotrophic and necrotrophic pathogens.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/imunologia , Interações Hospedeiro-Patógeno/imunologia , Oomicetos/fisiologia , Doenças das Plantas/imunologia , Imunidade Vegetal/imunologia , Fatores de Virulência/metabolismo , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Regulação da Expressão Gênica de Plantas , Doenças das Plantas/microbiologia , Virulência , Fatores de Virulência/genética
2.
PLoS Pathog ; 16(7): e1008680, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32673374

RESUMO

Pathogenic bacteria frequently acquire virulence traits via horizontal gene transfer, yet additional evolutionary innovations may be necessary to integrate newly acquired genes into existing regulatory pathways. The plant bacterial pathogen Pseudomonas syringae relies on a horizontally acquired type III secretion system (T3SS) to cause disease. T3SS-encoding genes are induced by plant-derived metabolites, yet how this regulation occurs, and how it evolved, is poorly understood. Here we report that the two-component system AauS-AauR and substrate-binding protein AatJ, proteins encoded by an acidic amino acid-transport (aat) and -utilization (aau) locus in P. syringae, directly regulate T3SS-encoding genes in response to host aspartate and glutamate signals. Mutants of P. syringae strain DC3000 lacking aauS, aauR or aatJ expressed lower levels of T3SS genes in response to aspartate and glutamate, and had decreased T3SS deployment and virulence during infection of Arabidopsis. We identified an AauR-binding motif (Rbm) upstream of genes encoding T3SS regulators HrpR and HrpS, and demonstrated that this Rbm is required for maximal T3SS deployment and virulence of DC3000. The Rbm upstream of hrpRS is conserved in all P. syringae strains with a canonical T3SS, suggesting AauR regulation of hrpRS is ancient. Consistent with a model of conserved function, an aauR deletion mutant of P. syringae strain B728a, a bean pathogen, had decreased T3SS expression and growth in host plants. Together, our data suggest that, upon acquisition of T3SS-encoding genes, a strain ancestral to P. syringae co-opted an existing AatJ-AauS-AauR pathway to regulate T3SS deployment in response to specific host metabolite signals.


Assuntos
Arabidopsis/microbiologia , Regulação Bacteriana da Expressão Gênica/fisiologia , Pseudomonas syringae/patogenicidade , Sistemas de Secreção Tipo III/fisiologia , Virulência/fisiologia , Doenças das Plantas/microbiologia
3.
PLoS One ; 15(6): e0235216, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32598374

RESUMO

A number of isothermal DNA amplification technologies claim to be ideal for point-of-need (PON) applications as they enable reactions to be performed using a single-temperature heat source (e.g. water bath). Thus, we examined several isothermal amplification methods focusing on simplicity, cost, sensitivity and reproducibility to identify the most suitable method(s) for low resource PON applications. A number of methods were found unsuitable as they either involved multiple temperature incubations, were relatively expensive or required relatively large amounts target DNA for amplification. Among the methods examined, loop-mediated isothermal amplification (LAMP) and recombinase polymerase amplification (RPA) were found to be the most suitable for PON applications as they are both single step methods that provide highly sensitive and reproducible amplifications. The speed of LAMP reactions was greatly enhanced, up to 76%, with the addition of loop primers while the presence of swarm primers and the sequestration of free magnesium ions with nucleotides also enhanced the amplification speed. In contrast, we were unable to enhance RPA's performance from the original published literature. While both RPA and LAMP have some drawbacks, either isothermal technology can reliably be used for on-site diagnostics with minimal equipment.


Assuntos
Arabidopsis/genética , DNA/análise , Fusarium/genética , Doenças das Plantas/genética , Arabidopsis/microbiologia , DNA/genética , Fusarium/patogenicidade , Técnicas de Amplificação de Ácido Nucleico , Doenças das Plantas/microbiologia , Temperatura
4.
Chemosphere ; 257: 127248, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32526471

RESUMO

The toxicity characteristics of HBCD and resistance mechanism of flavonols are investigated based on physiological and metagenomic analysis. Toxicology research of HBCD on Arabidopsis thaliana (Col and fls1-3) not only shows the toxic effect of HBCD on plants, but also indicates that flavonols could improve plant resistance to HBCD, including root length, shoot biomass and chlorophyll content. Analysis of eggNOG and GO enrichment demonstrates that HBCD has toxic effect on both gene expression and protein function, which concentrates on energy production - conversion and amino acid transport - metabolism. Differential expressed genes in flavonols-treated groups indicates that flavonols regulate the metabolism of amino acids, cofactors and vitamins, which is involved in plant defense system against oxidative damage caused by HBCD stress. HBCD is believed to affect the synthesis of proteins via genes expression of ribosome biogenesis process. Flavonols could strengthen the plant resistance and alleviate toxic effect under HBCD stress.


Assuntos
Arabidopsis/fisiologia , Flavonóis/metabolismo , Hidrocarbonetos Bromados/toxicidade , Poluentes do Solo/toxicidade , Arabidopsis/metabolismo , Arabidopsis/microbiologia , Metagenoma , Solo , Poluentes do Solo/metabolismo
5.
Gene ; 751: 144776, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32428700

RESUMO

Rice false smut (RFS), caused by Ustilaginoidea virens, is one of the most detrimental rice fungal diseases and pose a severe threat to rice production and quality. Effectors in U. virens often act as a set of essential virulence factors that play crucial roles in the interaction between host and the pathogen. Thus, the functions of each effector in U. virens need to be further explored. Here, a conserved small secreted hypersensitive response-inducing protein (hrip) was named UvHrip1. Functional validation was investigated to prove that UvHrip1 suppressed cell death symptom and ROS accumulation in Nicotiana benthamiana triggered by Burkholderia glumae. We performed transgenic technology to demonstrate UvHrip1 remarkably inhibited pathogen-associated molecular pattern-induced defense responses in Arabidopsis seedlings and plants, including the expression of defense-response genes. Furthermore, disease progression caused by the type III secretion system-defective mutant from Pseudomonas syringae pv. tomato DC3000 was strongly facilitated in transgenic Arabidopsis ectopic expressing UvHrip1. Our data demonstrated UvHrip1 suppresses plant innate immunity and promoting disease multiplication in Arabidopsis.


Assuntos
Arabidopsis/microbiologia , Proteínas Fúngicas/metabolismo , Hypocreales/patogenicidade , Doenças das Plantas/microbiologia , Arabidopsis/genética , Arabidopsis/imunologia , Arabidopsis/metabolismo , Burkholderia , Hypocreales/metabolismo , Imunidade Vegetal , Espécies Reativas de Oxigênio/metabolismo , Tabaco/metabolismo , Tabaco/microbiologia
6.
Nat Commun ; 11(1): 2114, 2020 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-32355217

RESUMO

Most plants associate with beneficial arbuscular mycorrhizal (AM) fungi that facilitate soil nutrient acquisition. Prior to contact, partner recognition triggers reciprocal genetic remodelling to enable colonisation. The plant Dwarf14-Like (D14L) receptor conditions pre-symbiotic perception of AM fungi, and also detects the smoke constituent karrikin. D14L-dependent signalling mechanisms, underpinning AM symbiosis are unknown. Here, we present the identification of a negative regulator from rice, which operates downstream of the D14L receptor, corresponding to the homologue of the Arabidopsis thaliana Suppressor of MAX2-1 (AtSMAX1) that functions in karrikin signalling. We demonstrate that rice SMAX1 is a suppressor of AM symbiosis, negatively regulating fungal colonisation and transcription of crucial signalling components and conserved symbiosis genes. Similarly, rice SMAX1 negatively controls strigolactone biosynthesis, demonstrating an unexpected crosstalk between the strigolactone and karrikin signalling pathways. We conclude that removal of SMAX1, resulting from D14L signalling activation, de-represses essential symbiotic programmes and increases strigolactone hormone production.


Assuntos
Proteínas de Arabidopsis/fisiologia , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Micorrizas/fisiologia , Oryza/microbiologia , Proteínas de Plantas/fisiologia , Simbiose , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Furanos/metabolismo , Regulação da Expressão Gênica de Plantas , Germinação , Compostos Heterocíclicos com 3 Anéis/metabolismo , Homozigoto , Peptídeos e Proteínas de Sinalização Intracelular/genética , Lactonas/metabolismo , Família Multigênica , Oryza/genética , Filogenia , Proteínas de Plantas/genética , Raízes de Plantas/microbiologia , Piranos/metabolismo , RNA-Seq , Transdução de Sinais
7.
Nature ; 580(7805): 653-657, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32350464

RESUMO

The aboveground parts of terrestrial plants, collectively called the phyllosphere, have a key role in the global balance of atmospheric carbon dioxide and oxygen. The phyllosphere represents one of the most abundant habitats for microbiota colonization. Whether and how plants control phyllosphere microbiota to ensure plant health is not well understood. Here we show that the Arabidopsis quadruple mutant (min7 fls2 efr cerk1; hereafter, mfec)1, simultaneously defective in pattern-triggered immunity and the MIN7 vesicle-trafficking pathway, or a constitutively activated cell death1 (cad1) mutant, carrying a S205F mutation in a membrane-attack-complex/perforin (MACPF)-domain protein, harbour altered endophytic phyllosphere microbiota and display leaf-tissue damage associated with dysbiosis. The Shannon diversity index and the relative abundance of Firmicutes were markedly reduced, whereas Proteobacteria were enriched in the mfec and cad1S205F mutants, bearing cross-kingdom resemblance to some aspects of the dysbiosis that occurs in human inflammatory bowel disease. Bacterial community transplantation experiments demonstrated a causal role of a properly assembled leaf bacterial community in phyllosphere health. Pattern-triggered immune signalling, MIN7 and CAD1 are found in major land plant lineages and are probably key components of a genetic network through which terrestrial plants control the level and nurture the diversity of endophytic phyllosphere microbiota for survival and health in a microorganism-rich environment.


Assuntos
Arabidopsis/genética , Arabidopsis/microbiologia , Redes Reguladoras de Genes/genética , Componentes Aéreos da Planta/genética , Componentes Aéreos da Planta/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/prevenção & controle , Arabidopsis/imunologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Morte Celular , Meio Ambiente , Firmicutes/genética , Firmicutes/isolamento & purificação , Genes de Plantas/genética , Genótipo , Fatores de Troca do Nucleotídeo Guanina/genética , Fatores de Troca do Nucleotídeo Guanina/metabolismo , Homeostase , Microbiota/genética , Microbiota/fisiologia , Mutação , Fenótipo , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Imunidade Vegetal/genética , Folhas de Planta/genética , Folhas de Planta/microbiologia , Proteobactérias/genética , Proteobactérias/isolamento & purificação
8.
BMC Bioinformatics ; 21(1): 142, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32293239

RESUMO

BACKGROUND: An important process for plant survival is the immune system. The induced systemic resistance (ISR) triggered by beneficial microbes is an important cost-effective defense mechanism by which plants are primed to an eventual pathogen attack. Defense mechanisms such as ISR depend on an accurate and context-specific regulation of gene expression. Interactions between genes and their products give rise to complex circuits known as gene regulatory networks (GRNs). Here, we explore the regulatory mechanism of the ISR defense response triggered by the beneficial bacterium Paraburkholderia phytofirmans PsJN in Arabidopsis thaliana plants infected with Pseudomonas syringae DC3000. To achieve this, a GRN underlying the ISR response was inferred using gene expression time-series data of certain defense-related genes, differential evolution, and threshold Boolean networks. RESULTS: One thousand threshold Boolean networks were inferred that met the restriction of the desired dynamics. From these networks, a consensus network was obtained that helped to find plausible interactions between the genes. A representative network was selected from the consensus network and biological restrictions were applied to it. The dynamics of the selected network showed that the largest attractor, a limit cycle of length 3, represents the final stage of the defense response (12, 18, and 24 h). Also, the structural robustness of the GRN was studied through the networks' attractors. CONCLUSIONS: A computational intelligence approach was designed to reconstruct a GRN underlying the ISR defense response in plants using gene expression time-series data of A. thaliana colonized by P. phytofirmans PsJN and subsequently infected with P. syringae DC3000. Using differential evolution, 1000 GRNs from time-series data were successfully inferred. Through the study of the network dynamics of the selected GRN, it can be concluded that it is structurally robust since three mutations were necessary to completely disarm the Boolean trajectory that represents the biological data. The proposed method to reconstruct GRNs is general and can be used to infer other biologically relevant networks to formulate new biological hypotheses.


Assuntos
Arabidopsis/genética , Arabidopsis/microbiologia , Resistência à Doença/genética , Redes Reguladoras de Genes , Burkholderiaceae/fisiologia , Pseudomonas syringae
9.
J Plant Res ; 133(3): 409-417, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32227262

RESUMO

To fine tune defense response output, plants recruit both positive and negative regulators. Here we report Arabidopsis DORMANCY/AUXIN ASSOCIATED FAMILY PROTEIN 2(DAP2) gene as a negative regulator of basal defense against virulent bacterial pathogens. Expression of DAP2 enhances upon pathogen inoculation. Our experiments show that DAP2 suppressed resistance against virulent strains of bacterial pathogens, pathogen-induced callose deposition, and ROS accumulation; however, it did not influence effector-triggered immunity. In addition, DAP2 negatively regulated systemic acquired resistance (SAR). DAP2 expression was enhanced in the pathogen-free systemic tissues of SAR-induced plants. Previously, Arabidopsis Flowering locus D (FLD) gene has been shown to be essential for SAR but not for local resistance. We show here that FLD function is necessary for SAR-induced expression of DAP2, suggesting DAP2 as a target of FLD for activation of SAR in Arabidopsis.


Assuntos
Proteínas de Arabidopsis/fisiologia , Arabidopsis/fisiologia , Resistência à Doença , Doenças das Plantas/microbiologia , Arabidopsis/microbiologia , Regulação da Expressão Gênica de Plantas
10.
J Vis Exp ; (157)2020 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-32225152

RESUMO

Ralstonia solanacearum is a devastating soil borne vascular pathogen that can infect a large range of plant species, causing an important threat to agriculture. However, the Ralstonia model is considerably underexplored in comparison to other models involving bacterial plant pathogens, such as Pseudomonas syringae in Arabidopsis. Research targeted to understanding the interaction between Ralstonia and crop plants is essential to develop sustainable solutions to fight against bacterial wilt disease but is currently hindered by the lack of straightforward experimental assays to characterize the different components of the interaction in native host plants. In this scenario, we have developed a method to perform genetic analysis of Ralstonia infection of tomato, a natural host of Ralstonia. This method is based on Agrobacterium rhizogenes-mediated transformation of tomato roots, followed by Ralstonia soil-drenching inoculation of the resulting plants, containing transformed roots expressing the construct of interest. The versatility of the root transformation assay allows performing either gene overexpression or gene silencing mediated by RNAi. As a proof of concept, we used this method to show that RNAi-mediated silencing of SlCESA6 in tomato roots conferred resistance to Ralstonia. Here, we describe this method in detail, enabling genetic approaches to understand bacterial wilt disease in a relatively short time and with small requirements of equipment and plant growth space.


Assuntos
Lycopersicon esculentum/genética , Lycopersicon esculentum/microbiologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Raízes de Plantas/microbiologia , Ralstonia solanacearum/fisiologia , Transformação Genética , Agrobacterium/metabolismo , Antibacterianos/farmacologia , Arabidopsis/microbiologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Inativação Gênica/efeitos dos fármacos , Lycopersicon esculentum/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Ralstonia solanacearum/efeitos dos fármacos , Ralstonia solanacearum/crescimento & desenvolvimento , Reprodutibilidade dos Testes , Solo , Transformação Genética/efeitos dos fármacos
11.
Artigo em Inglês | MEDLINE | ID: mdl-32112998

RESUMO

Triunsaturated fatty acids are substrates for the synthesis of the defense hormone jasmonate which plays roles in resistance to numerous fungal pathogens. However, relatively little is known about other potential roles of di-unsaturated and triunsaturated fatty acids in resistance to fungal pathogens - in particular those that can attack plants at the seedling stage. We examined the roles of polyunsaturated fatty acids (PUFAs) in Arabidopsis thaliana during attack by the necrotrophic pathogen, Botrytis cinerea. We found that PUFA-deficient Arabidopsis mutants (fad2-1, fad2-3 and fad3-2 fad7-2 fad8 [fad trip]) displayed an unexpectedly strong resistance to B. cinerea at the cotyledon stage. Preliminary analyses revealed no changes in the expression of defense genes, however cuticle permeability defects were detected in both fad2-1 and fad trip mutants. Analysis of B. cinerea development on the surface of cotyledons revealed arrested hyphal growth on fad2-3 and fad trip mutants and 28% reduction in fungal adhesion on fad2-3 cotyledons. Surface metabolite analysis from the cotyledons of PUFA mutants led to the identification of 7-methylsulfonylheptyl glucosinolate (7MSOHG), which over-accumulated on the plant surface. We linked the appearance of 7MSOHG to defects in cuticle composition and permeability of mutants and show that its appearance correlates with resistance to B. cinerea.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Botrytis , Glucosinolatos , Antifúngicos/farmacologia , Arabidopsis/química , Arabidopsis/genética , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Botrytis/efeitos dos fármacos , Resistência à Doença/genética , Ácidos Graxos Dessaturases/genética , Ácidos Graxos Dessaturases/metabolismo , Regulação da Expressão Gênica de Plantas , Glucosinolatos/genética , Glucosinolatos/farmacologia
12.
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
13.
Artigo em Inglês | MEDLINE | ID: mdl-32222680

RESUMO

Bacillus amyloliquefaciens is a non-pathogenic and plant growth-promoting rhizobacterium that enhances plant resistance to drought and diseases. Arabidopsis thaliana is a multipurpose model plant for exploring microorganism-plant interactions and a crucial vegetal tool for molecular research. Non-coding RNAs are RNA molecules involved in the regulation of various biological functions and constitute a research hotspot in the field of plant biology. In this study, the effect of B. amyloliquefaciens treatment on the resistance of A. thaliana to high calcium stress was analyzed. The transcriptome sequencing of A. thaliana roots under four treatment conditions was performed to screen differentially expressed lncRNAs, mRNAs and miRNAs. Functional analysis was also performed to understand the potential mechanism by which B. amyloliquefaciens-regulated lncRNAs, miRNAs and mRNAs affect the resistance of A. thaliana to high calcium stress. The results indicated that B. amyloliquefaciens treatment increased the resistance of A. thaliana to high calcium stress. A set of differentially expressed lncRNAs, mRNAs and miRNAs were screened between the high calcium and control group on one hand, and high calcium and high calcium + B. amyloliquefaciens groups on the other hand. Functional analysis indicated that the differentially expressed mRNAs and miRNA were involved in various biological functions and that transcriptional dysregulation caused by high calcium stress involves metabolic processes rather than defense responses. Conclusively, B. amyloliquefaciens may improve the resistance of A. thaliana to high calcium stress via a lncRNA-miRNA-mRNA regulatory network. These findings will contribute to the development of agriculture in karst regions with high calcium content.


Assuntos
Arabidopsis/fisiologia , Bacillus amyloliquefaciens , Cálcio/efeitos adversos , MicroRNAs/genética , RNA Longo não Codificante/genética , RNA Mensageiro/genética , Arabidopsis/genética , Arabidopsis/microbiologia , Redes Reguladoras de Genes
14.
Science ; 367(6479): 763-768, 2020 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-32054757

RESUMO

Effector-triggered immunity (ETI), induced by host immune receptors in response to microbial effectors, protects plants against virulent pathogens. However, a systematic study of ETI prevalence against species-wide pathogen diversity is lacking. We constructed the Pseudomonas syringae Type III Effector Compendium (PsyTEC) to reduce the pan-genome complexity of 5127 unique effector proteins, distributed among 70 families from 494 strains, to 529 representative alleles. We screened PsyTEC on the model plant Arabidopsis thaliana and identified 59 ETI-eliciting alleles (11.2%) from 19 families (27.1%), with orthologs distributed among 96.8% of P. syringae strains. We also identified two previously undescribed host immune receptors, including CAR1, which recognizes the conserved effectors AvrE and HopAA1, and found that 94.7% of strains harbor alleles predicted to be recognized by either CAR1 or ZAR1.


Assuntos
Arabidopsis/imunologia , Arabidopsis/microbiologia , Interações Hospedeiro-Patógeno/imunologia , Imunidade Inata/genética , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Imunidade Vegetal/genética , Pseudomonas syringae/patogenicidade , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/imunologia , Proteínas de Transporte/genética , Proteínas de Transporte/fisiologia , Genoma de Planta , Interações Hospedeiro-Patógeno/genética , Doenças das Plantas/genética , Pseudomonas syringae/genética
15.
PLoS One ; 15(2): e0228560, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32027711

RESUMO

Culture-independent characterization of microbial communities associated with popular plant model systems have increased our understanding of the plant microbiome. However, the integration of other model systems, such as duckweed, could facilitate our understanding of plant microbiota assembly and evolution. Duckweeds are floating aquatic plants with many characteristics, including small size and reduced plant architecture, that suggest their use as a facile model system for plant microbiome studies. Here, we investigated the structure and assembly of the duckweed bacterial microbiome. First, a culture-independent survey of the duckweed bacterial microbiome from different locations in New Jersey revealed similar phylogenetic profiles. These studies showed that Proteobacteria is a dominant phylum in the duckweed bacterial microbiome. To observe the assembly dynamics of the duckweed bacterial community, we inoculated quasi-gnotobiotic duckweed with wastewater effluent from a municipal wastewater treatment plant. Our results revealed that duckweed strongly shapes its bacterial microbiome and forms distinct associations with bacterial community members from the initial inoculum. Additionally, these inoculation studies showed the bacterial communities of different duckweed species were similar in taxa composition and abundance. Analysis across the different duckweed bacterial communities collected in this study identified a set of "core" bacterial taxa consistently present on duckweed irrespective of the locale and context. Furthermore, comparison of the duckweed bacterial community to that of rice and Arabidopsis revealed a conserved taxonomic structure between the duckweed microbiome and the terrestrial leaf microbiome. Our results suggest that duckweeds utilize similar bacterial community assembly principles as those found in terrestrial plants and indicate a highly conserved structuring effect of leaf tissue on the plant microbiome.


Assuntos
Araceae/microbiologia , Microbiota , Filogenia , Folhas de Planta/microbiologia , Arabidopsis/microbiologia , Bactérias/genética , New Jersey , Oryza/microbiologia , Proteobactérias , RNA Ribossômico 16S/análise , Águas Residuárias/microbiologia
16.
Mol Plant Microbe Interact ; 33(6): 808-824, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32101077

RESUMO

Trichoderma spp. are filamentous fungi that colonize plant roots conferring beneficial effects to plants, either indirectly through the induction of their defense systems or directly through the suppression of phytopathogens in the rhizosphere. Transcriptomic analyses of Trichoderma spp. emerged as a powerful method for identifying the molecular events underlying the establishment of this beneficial relationship. Here, we focus on the transcriptomic response of Trichoderma virens during its interaction with Arabidopsis seedlings. The main response of T. virens to cocultivation with Arabidopsis was the repression of gene expression. The biological processes of transport and metabolism of carbohydrates were downregulated, including a set of cell wall-degrading enzymes putatively relevant for root colonization. Repression of such genes reached their basal levels at later times in the interaction, when genes belonging to the biological process of copper ion transport were induced, a necessary process providing copper as a cofactor for cell wall-degrading enzymes with the auxiliary activities class. RNA-Seq analyses showed the induction of a member of the SNF2 family of chromatin remodelers/helicase-related proteins, which was named IPA-1 (increased protection of Arabidopsis-1). Sequence analyses of IPA-1 showed its closest relatives to be members of the Rad5/Rad16 and SNF2 subfamilies; however, it grouped into a different clade. Although deletion of IPA-1 in T. virens did not affect its growth, the antibiotic activity of Δipa-1 culture filtrates against Rhizoctonia solani diminished but it remained unaltered against Botrytis cinerea. Triggering of the plant defense genes in plants treated with Δipa-1 was higher, showing enhanced resistance against Pseudomonas syringae but not against B. cinerea as compared with the wild type.


Assuntos
Antibiose , Arabidopsis/microbiologia , Montagem e Desmontagem da Cromatina , Resistência à Doença , Rhizoctonia/patogenicidade , Trichoderma/fisiologia , Humanos , Doenças das Plantas/microbiologia , Raízes de Plantas , Transcriptoma
17.
Artigo em Inglês | MEDLINE | ID: mdl-32018064

RESUMO

Soil is a primary source of water and inorganic nutrients vital for plant growth. In particular, the rhizosphere, a microecological region around the plant roots, is enriched with root exudates that enable beneficial microbial communities to form. Plant growth-promoting rhizobacteria (PGPR) are rhizosphere bacteria that contribute to the improvement of plant growth through diverse physiological mechanisms. Identifying PGPR is beneficial for agriculture because their use can effectively increase the productivity of plants without the harmful side effects of chemical fertilizers. To further enrich the pool of PGPR that contribute to abiotic stress resistance in plants, we screened roughly 491 bacteria that had previously been isolated in soil from Gotjawal in Jeju island, South Korea. Among several candidates, the application of Bacillus subtilis strain GOT9, led to the enhancement of drought and salt stress tolerance in Arabidopsis. In agreement with the increased stress tolerance phenotypes, its application resulted in increases in the transcripts of various drought stress- and salt stress-inducible genes in the absence or presence of the stresses. Furthermore, the treatment resulted in improved lateral root growth and development in Arabidopsis. GOT9 also led to enhanced tolerance against drought and salt stresses and to upregulation of drought-inducible genes in Brassica, a closely related crop to Arabidopsis. Taken together, these results show that GOT9 could be utilized as a biotic resource that effectively minimizes damage to plants from environmental stresses.


Assuntos
Arabidopsis , Bacillus subtilis , Brassica , Secas , Interações entre Hospedeiro e Microrganismos , Estresse Fisiológico , Arabidopsis/microbiologia , Bacillus subtilis/fisiologia , Brassica/microbiologia , Interações entre Hospedeiro e Microrganismos/fisiologia , Desenvolvimento Vegetal
18.
BMC Plant Biol ; 20(1): 49, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32000681

RESUMO

BACKGROUND: Biotrophic fungi make intimate contact with host cells to access nutrients. Sugar is considered as the main carbon sources absorbed from host cells by pathogens. Partition, exchanges and competition for sugar at plant-pathogen interfaces are controlled by sugar transporters. Previous studies have indicated that the leaf rust resistance (Lr) gene Lr67, a natural mutation of TaSTP13 encoding a wheat sugar transport protein, confers partial resistance to all three wheat rust species and powdery mildew possibly due to weakened sugar transport activity of TaSTP13 by heterodimerization. However, one major problem that remains unresolved concerns whether TaSTP13 participates in wheat susceptibility to rust and mildew. RESULTS: In this study, expression of TaSTP13 was highly induced in wheat leaves challenged by Puccinia striiformis f. sp. tritici (Pst) and certain abiotic treatments. TaSTP13 was localized in the plasma membrane and functioned as homooligomers. In addition, a functional domain for its transport activity was identified in yeast. Suppression of TaSTP13 reduced wheat susceptibility to Pst by barley stripe mosaic virus-induced gene silencing (VIGS). While overexpression of TaSTP13 promoted Arabidopsis susceptibility to powdery mildew and led to increased glucose accumulation in the leaves. CONCLUSIONS: These results indicate that TaSTP13 is transcriptionally induced and contributes to wheat susceptibility to stripe rust, possibly by promoting cytoplasmic hexose accumulation for fungal sugar acquisition in wheat-Pst interactions.


Assuntos
Basidiomycota/fisiologia , Regulação da Expressão Gênica de Plantas , Hexoses/metabolismo , Doenças das Plantas/microbiologia , Triticum/genética , Arabidopsis/genética , Arabidopsis/microbiologia , Ascomicetos/fisiologia , Basidiomycota/genética , Citoplasma/metabolismo , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/microbiologia , Triticum/microbiologia
19.
Cell ; 180(3): 440-453.e18, 2020 02 06.
Artigo em Inglês | MEDLINE | ID: mdl-32032516

RESUMO

Recognition of microbe-associated molecular patterns (MAMPs) is crucial for the plant's immune response. How this sophisticated perception system can be usefully deployed in roots, continuously exposed to microbes, remains a mystery. By analyzing MAMP receptor expression and response at cellular resolution in Arabidopsis, we observed that differentiated outer cell layers show low expression of pattern-recognition receptors (PRRs) and lack MAMP responsiveness. Yet, these cells can be gated to become responsive by neighbor cell damage. Laser ablation of small cell clusters strongly upregulates PRR expression in their vicinity, and elevated receptor expression is sufficient to induce responsiveness in non-responsive cells. Finally, localized damage also leads to immune responses to otherwise non-immunogenic, beneficial bacteria. Damage-gating is overridden by receptor overexpression, which antagonizes colonization. Our findings that cellular damage can "switch on" local immune responses helps to conceptualize how MAMP perception can be used despite the presence of microbial patterns in the soil.


Assuntos
Arabidopsis/imunologia , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Raízes de Plantas/imunologia , Receptores de Reconhecimento de Padrão/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/microbiologia , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/efeitos da radiação , Ascorbato Peroxidases/metabolismo , Ascorbato Peroxidases/efeitos da radiação , Flagelina/farmacologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Terapia a Laser/métodos , Proteínas de Membrana/metabolismo , Proteínas de Membrana/efeitos da radiação , Microscopia Confocal , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/microbiologia , Raízes de Plantas/efeitos da radiação , Proteínas Quinases/metabolismo , Proteínas Quinases/efeitos da radiação , Receptores de Reconhecimento de Padrão/efeitos da radiação , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/efeitos da radiação , Imagem com Lapso de Tempo
20.
Plant Mol Biol ; 103(1-2): 173-184, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32100164

RESUMO

KEY MESSAGE: Arabidopsis LONG-CHAIN BASE KINASE 1 (LCBK1) interacts with MEDEA, a component of PCR2 complex that negatively regulates immunity. LCBK1 phosphorylates phytosphingosine and thereby promotes stomatal immunity against bacterial pathogens. Arabidopsis polycomb-group repressor complex2 (PRC2) protein MEDEA (MEA) suppresses both pattern-triggered immunity (PTI) and effector-triggered immunity (ETI). MEA represses the expression of RPS2 and thereby attenuates AvrRpt2 effector-mediated ETI. However, the mechanism of MEA-mediated PTI diminution was not known. By screening the Arabidopsis cDNA library using yeast-2-hybrid interaction, we identified LONG-CHAIN BASE KINASE1 (LCBK1) as an MEA-interacting protein. We found that lcbk1 mutants are susceptible to virulent bacterial pathogens, such as Pseudomonas syringae pv maculicola (Psm) and P. syringae pv tomato (Pst) but not the avirulent strain of Pst that carries AvrRpt2 effector. Pathogen inoculation induces LCBK1 expression, especially in guard cells. We found that LCBK1 has a positive regulatory role in stomatal closure after pathogen inoculation. WT plants close stomata within an hour of Pst inoculation or flg22 (a 22 amino acid peptide from bacterial flagellin protein that activates PTI) treatment, but not lcbk1 mutants. LCBK1 phosphorylates phytosphingosine (PHS). Exogenous application of phosphorylated PHS (PHS-P) induces stomatal closure and rescues loss-of-PTI phenotype of lcbk1 mutant plants. MEA overexpressing (MEA-Oex) plants are defective, whereas loss-of-function mea-6 mutants are hyperactive in PTI-induced stomatal closure. Exogenous application of PHS-P rescues loss-of-PTI in MEA-Oex plants. Results altogether demonstrate that LCBK1 is an interactor of MEA that positively regulates PTI-induced stomatal closure in Arabidopsis.


Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/imunologia , Fosfotransferases/metabolismo , Estômatos de Plantas/imunologia , Arabidopsis/enzimologia , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Fosfotransferases/genética , Doenças das Plantas/imunologia , Esfingosina/análogos & derivados , Esfingosina/metabolismo
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