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1.
Plant Dis ; 104(1): 13-15, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31660797

RESUMO

Xanthomonas translucens pv. translucens causes bacterial leaf streak and bacterial blight diseases of barley. This pathogen limits barley production globally but remains understudied, with limited genomic resources. To better understand the biology of this X. translucens subgroup, we sequenced the complete genome of the X. translucens pv. translucens strain UPB886.


Assuntos
Genoma Bacteriano , Xanthomonas , Genoma Bacteriano/genética , Genômica , Hordeum/microbiologia , Doenças das Plantas/microbiologia , Xanthomonas/genética
2.
Plant Dis ; 104(1): 198-203, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31738688

RESUMO

A single loop-mediated isothermal amplification (LAMP) assay was developed for specific detection of both pathogens that cause bacterial blight in common bean, Xanthomonas phaseoli pv. phaseoli (Xpp) and Xanthomonas citri pv. fuscans (Xcf). The objective was to provide a simple, easy-to-use, specific, and sensitive method to investigate the presence of one or both pathogens in plant material and seeds for routine diagnosis. The detection limits for both pathogens were 10 CFU/ml for cell suspensions and 1 fg of DNA, whereas in conventional PCR, the primers detected up to 105 CFU/ml and 1 ng of DNA. Specificity was confirmed by testing DNA from bean leaves, other Xanthomonas species, common fungal and bacterial bean pathogens, and bacteria from the leaf microbiota. The method was tested with bean leaves inoculated with Xpp, and the pathogen could be detected from 4 h up to 15 days postinoculation, even before disease symptoms were visible. When the method was applied to bacterium detection (Xpp or Xcf) in seed lots from infected plants, the bacterium detection rate was 100% (24 of 24). The pathogens were detected in seeds incubated for just 1 h in saline solution (0.85%), reducing the time needed for bacterium detection. The LAMP assay could be useful as a tool in bean bacterial blight management. Rapid and sensitive detection of bacteria in bean seed lots would reduce the risks of planting highly contaminated seeds in environments favorable to blight multiplication.


Assuntos
Agricultura , Técnicas de Amplificação de Ácido Nucleico , Phaseolus , Xanthomonas , Agricultura/métodos , Limite de Detecção , Phaseolus/microbiologia , Doenças das Plantas/microbiologia , Sementes/microbiologia , Xanthomonas/fisiologia
3.
Plant Dis ; 104(2): 423-429, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31804901

RESUMO

Bacterial spot of tomato is a foliar disease caused by four Xanthomonas species. Identifying genetic resistance in wild tomatoes and subsequent breeding of varieties has been a strategy to reduce the loss from this disease because control using pesticides has been ineffective. Three independent sources of resistance have been identified with quantitative trait loci (QTL) mapping to the centromeric region on chromosome 11. These sources are derived from Hawaii 7998 (QTL-11A), PI 114490 (QTL-11B), and LA2533 (QTL-11C). To determine which QTL introgression from chromosome 11 provides the greatest resistance to multiple species, we developed near-isogenic lines (NILs) using marker-assisted backcrossing. In parallel, we developed an NIL that contains Rx-4/Xv3, which provides major gene resistance to Xanthomonas perforans. Additionally, we combined Rx-4/Xv3 resistance with QTL-11A. These sources of resistance were independently introduced into the susceptible parent, OH88119. During a 3-year period from 2016 to 2018, we evaluated backcross-derived families and NILs from each source in independent field trials inoculated with X. perforans, X. euvesicatoria, or X. gardneri. Our results suggest that both QTL-11C and QTL-11A combined with Rx-4/Xv3 provide effective genetic resistance against multiple Xanthomonas species. In addition, we provide evidence for additive to dominant genetic action for the QTL introgressions.


Assuntos
Lycopersicon esculentum , Xanthomonas , Hawaii , Doenças das Plantas , Locos de Características Quantitativas
4.
Phytopathology ; 110(2): 287-296, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31713458

RESUMO

Citrus canker (CC), caused by the bacterial pathogen Xanthomonas citri subsp. citri, impacts citrus production in many areas of the world by reducing yields, degrading tree health, and severely blemishing the outer peels of fresh fruit. The relative susceptibility to CC among different species of Citrus varies from the highly susceptible lime (Citrus × aurantifolia), sweet orange (C. × sinensis), and grapefruit (C. × paradisi) to the much less susceptible calamondin (C. × microcarpa) and kumquat (C. japonica). This investigation compares the responses to infection with X. citri subsp. citri of these five genotypes with respect to phenylpropanoid compound profiles and relative increases or decreases of specific compounds postinoculation. In response to X. citri subsp. citri infection, all hosts possessed increased concentrations of phenylpropanoids in leaf tissue, whereas the similarly treated nonhost orange jessamine (Murraya paniculata) did not. Several of the tested genotypes exhibited notably increased production of fluorescent phenylpropanoids, including umbelliferone, herniarin, auraptene, scoparone, and others. The profiles of these compounds and their levels of production varied among the tested species yet all investigated Citrus genotypes exhibited increased concentrations of phenylpropanoids regardless of their degree of susceptibility to X. citri subsp. citri. Kumquat and calamondin, the tested genotypes least susceptible to X. citri subsp. citri, also exhibited the highest levels of the dihydrochalcone 3',5'-di-C-glucosyl phloretin, the aglycone portion of which, phloretin, is a known antibiotic, although levels of this compound were not affected by inoculation with X. citri subsp. citri.


Assuntos
Citrus , Interações Hospedeiro-Patógeno , Folhas de Planta , Xanthomonas , Citrus/microbiologia , Folhas de Planta/microbiologia , Xanthomonas/fisiologia
5.
Phytopathology ; 110(2): 257-266, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31448998

RESUMO

Bacterial leaf streak (BLS) of wheat and barley has been a disease of increasing concern in the Upper Midwest over the past decade. In this study, intra- and interfield genetic and pathogenic diversity of bacteria causing BLS in Minnesota was evaluated. In 2015, 89 strains were isolated from 100 leaf samples collected from two wheat and two barley fields naturally infected with BLS. Virulence assays and multilocus sequence alignments of four housekeeping genes supported pathovar identifications. All wheat strains were pathogenic on wheat and barley and belonged to the same lineage as the Xanthomonas translucens pv. undulosa-type strain. All barley strains were pathogenic on barley but not on wheat. Three lineages of barley strains were detected. The frequency and number of sequence types of each pathovar varied within and between fields. A significant population variance was detected between populations of X. translucens pv. undulosa collected from different wheat fields. Population stratification of X. translucens pv. translucens was not detected. Significant differences in virulence were detected among three dominant sequence types of X. translucens pv. undulosa but not those of X. translucens pv. translucens. Field trials with wheat and barley plants inoculated with strains of known sequence type and virulence did not detect significant race structures within either pathovar. Knowledge of virulence, sequence types, and population structures of X. translucens on wheat and barley can support studies on plant-bacterial interactions and breeding for BLS disease resistance.


Assuntos
Variação Genética , Hordeum , Doenças das Plantas , Triticum , Xanthomonas , Hordeum/microbiologia , Especificidade de Hospedeiro , Minnesota , Doenças das Plantas/microbiologia , Triticum/microbiologia , Xanthomonas/classificação , Xanthomonas/genética , Xanthomonas/patogenicidade
6.
Phytopathology ; 110(2): 267-277, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31464159

RESUMO

Bacterial leaf blight caused by Xanthomonas oryzae pv. oryzae represents a severe threat to rice cultivation in Mali. Characterizing the pathotypic diversity of bacterial populations is key to the management of pathogen-resistant varieties. Forty-one X. oryzae pv. oryzae isolates were collected between 2010 and 2013 in the major rice growing regions in Mali. All isolates were virulent on the susceptible rice variety Azucena; evaluation of the isolates on 12 near isogenic rice lines, each carrying a single resistance gene, identified six new races (A4 to A9) and confirmed race A3 that was previously reported in Mali. Races A5 and A6, isolated in Office du Niger and Sélingué, were the most prevalent races in Mali. Race A9 was the most virulent, circumventing all of the resistance genes tested. Xa3 controlled six of seven races (i.e., 89% of the isolates tested). The expansion of race A9 represents a major risk to rice cultivation and highlights the urgent need to identify a local source of resistance. We selected 14 isolates of X. oryzae pv. oryzae representative of the most prevalent races to evaluate 29 rice varieties grown by farmers in Mali. Six isolates showed a high level of resistance to X. oryzae pv. oryzae and were then screened with a larger collection of isolates. Based on the interactions among the six varieties and the X. oryzae pv. oryzae isolates, we characterized eight different pathotypes (P1 to P8). Two rice varieties, SK20-28 and Gigante, effectively controlled all of the isolates tested. The low association observed among races and pathotypes of X. oryzae pv. oryzae suggests that the resistance observed in the local rice varieties does not simply rely on single known Xa genes. X. oryzae pv. oryzae is pathogenically and geographically diverse. Both the races of X. oryzae pv. oryzae characterized in this study and the identification of sources of resistance in local rice varieties provide useful information to inform the design of effective breeding programs for resistance to bacterial leaf blight in Mali.


Assuntos
Oryza , Xanthomonas , Mali , Doenças das Plantas
7.
Biosci. j. (Online) ; 35(6): 1728-1746, nov./dec. 2019. tab, ilus, graf
Artigo em Inglês | LILACS | ID: biblio-1049098

RESUMO

Bacterial spot (Xanthomonas axonopodis pv. passiflorae) significantly reduces yellow passion fruit (Passiflora edulis Sims) yield and longevity. A standard area diagram set (SADs) for severity assessment of bacterial spot on tri-lobed leaves of yellow passion was developed and validated in this study. The SADs consisted of eight severity levels (2; 4; 9; 18; 35; 58; 80; and 94%). For its validation, 20 raters, who initially estimated the disease severity without the aid of the SADs, were divided into four groups (G1 and G3, inexperienced; G2 and G4, experienced). Subsequently, G1 and G2 performed the second evaluation without the SADs, and G3 and G4 completed the second evaluation with the proposed SADs. The accuracy and precision of the assessments were determined by simple linear regression and by the Lin's concordance correlation coefficient (LCCC). The proposed SADs allowed accurate and precise quantification of bacterial spot severity, increasing the agreement between estimated and actual values. Inexperienced raters benefited the most from the use of the SADs. The increase in accuracy and precision in the non-aided groups, when present, was less pronounced than those increments observed in the SADs-aided groups. The LCCC confirmed the increases in accuracy and precision detected by the linear regression analysis.


A bacteriose (Xanthomonas axonopodis pv. passiflorae) reduz significativamente a produção e longevidade do maracujazeiro azedo (Passiflora edulis Sims). Uma escala diagramática para a avaliação da severidade da bacteriose em folhas trilobadas do maracujazeiro azedo foi desenvolvida e validada neste estudo. A escala diagramática apresentou oito níveis de severidade (2; 4; 9; 18; 35; 58; 80 e 94%). Para a sua validação, os 20 avaliadores foram divididos em quatro grupos (G1 e G3, sem experiência; G2 e G4, com experiência), que inicialmente estimaram a severidade da doença sem auxílio da escala. Posteriormente, G1 e G2 fizeram outra avaliação sem escala, e G3 e G4 realizaram a avaliação com a escala proposta. A acurácia e a precisão das estimativas foram determinadas por regressão linear simples e pelo coeficiente de correlação de concordância de Lin (LCCC). A escala diagramática proposta permitiu quantificar a severidade da bacteriose de forma acurada e precisa, aumentando a concordância entre os valores estimados e os reais. Os avaliadores inexperientes foram os mais beneficiados pelo uso da escala. O aumento da acurácia e precisão nos grupos que realizaram dupla avaliação sem escala, quando ocorreu, foi mais discreto que os incrementos observados nos grupos que utilizaram a escala. O LCCC confirmou os incrementos da acurácia e precisão detectados pela análise de regressão linear.


Assuntos
Xanthomonas , Passiflora
8.
J Agric Food Chem ; 67(48): 13212-13220, 2019 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-31702905

RESUMO

Because only a handful of agrochemicals can manage bacterial infections, the discovery and development of innovative, inexpensive, and high-efficiency antibacterial agents targeting these infections are challenging. Herein, a series of novel epimeric and chiral 18ß-glycyrrhetinic acid (GA) ester derivatives with various tertiary amine pendants were designed, synthesized, and screened for pharmacological activity. Results showed that some of the title compounds were conferred with significantly enhanced antibacterial activity toward phytopathogens Xanthomonas oryzae pv oryzae (A2, B1-B3, and C1, EC50 values within 3.81-4.82 µg/mL) and Xanthomonas axonopodis pv citri (B1, EC50 = 3.18 µg/mL; B2, EC50 = 2.76 µg/mL). These activities are superior to those of GA (EC50 > 400 µg/mL), thiodiazole copper, and bismerthiazol. Pharmacophore studies revealed that the synergistic combination of GA skeleton and tertiary amine scaffolds contributed to the biological actions. In vivo experiments displayed their promising applications in controlling bacterial infections. Antibacterial mechanism studies revealed that the title compounds could trigger apoptosis in the tested pathogens, evident by bacteria morphological changes observed in scanning electron microscopy images. This outcome should motivate the development of various apoptosis inducers against plant bacterial diseases by a novel mode of action compared to that of existing agricultural chemicals.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Apoptose/efeitos dos fármacos , Ácido Glicirretínico/análogos & derivados , Antibacterianos/síntese química , Desenho de Drogas , Ésteres/química , Ácido Glicirretínico/síntese química , Ácido Glicirretínico/química , Ácido Glicirretínico/farmacologia , Testes de Sensibilidade Microbiana , Doenças das Plantas/microbiologia , Propanolaminas/química , Estereoisomerismo , Relação Estrutura-Atividade , Xanthomonas/citologia , Xanthomonas/efeitos dos fármacos
9.
J Agric Food Chem ; 67(50): 13904-13913, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31765135

RESUMO

A series of N-aryl-pyridine-4-one derivatives were designed and synthesized using maltol and antidesmone as lead compounds, and then their fungicidal/bactericidal activities and possible mechanism of action against Colletotrichum musae were explored. Most of these compounds exhibited significant fungicidal activity in vitro. Especially, compound 23 has more than 90% inhibitory activity against nine plant pathogenic fungi at 50 µg mL-1, which is superior to azoxystrobin. Moreover, an in vivo bioassay also demonstrated that compound 23 exhibited high-efficiency broad-spectrum antifungal activity and can effectively control postharvest diseases of mango. In addition, it was found that compounds 22 and 23 can also effectively control rice bacterial leaf blight in pot experiments, which was even more effective than zhongshengmycin. Preliminary mechanism studies revealed that compound 23 may cause cell membrane and mitochondria destruction. These findings indicate that compound 23 can be used to develop potential agrochemical fungicides and bactericides.


Assuntos
Agroquímicos/química , Agroquímicos/farmacologia , Antibacterianos/química , Antibacterianos/farmacologia , Fungicidas Industriais/química , Fungicidas Industriais/farmacologia , Agroquímicos/síntese química , Colletotrichum/efeitos dos fármacos , Fungicidas Industriais/síntese química , Mangifera/microbiologia , Estrutura Molecular , Oryza/microbiologia , Doenças das Plantas/microbiologia , Piridinas/química , Piridinas/farmacologia , Rhizoctonia , Relação Estrutura-Atividade , Xanthomonas/efeitos dos fármacos , Xanthomonas/crescimento & desenvolvimento
10.
J Agric Food Chem ; 67(46): 12696-12708, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31657554

RESUMO

In this study, a type of thiazolium-labeled 1,3,4-oxadiazole thioether bridged by diverse alkyl chain lengths was constructed. The antimicrobial activity of the fabricated thioether toward plant pathogenic bacteria and fungi was then screened. Antibacterial evaluation indicated that title compounds possess specific characteristics that enable them to severely attack three phytopathogens, namely, Xanthomonas oryzae pv. oryzae, Ralstonia solanacearum, and Xanthomonas axonopodis pv. citri with minimal EC50 values of 0.10, 3.27, and 3.50 µg/mL, respectively. Three-dimensional quantitative structure-activity relationship models were established to direct the following excogitation for exploring higher active drugs. The in vivo study against plant bacterial diseases further identified the prospective application of title compounds as alternative antibacterial agents. The proteomic technique, scanning electron microscopy patterns, and fluorescence spectrometry were exploited to investigate the antibacterial mechanism. Additionally, some target compounds performed superior inhibitory actions against three tested fungal strains. In view of their simple molecular architecture and highly efficient bioactivity, these substrates could be further explored as promising surrogates for fighting against plant microbial infections.


Assuntos
Antibacterianos/farmacologia , Oxidiazóis/farmacologia , Sulfetos/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Testes de Sensibilidade Microbiana , Oxidiazóis/síntese química , Oxidiazóis/química , Doenças das Plantas/microbiologia , Ralstonia/efeitos dos fármacos , Sulfetos/síntese química , Sulfetos/química , Xanthomonas/efeitos dos fármacos
11.
Int J Mol Sci ; 20(20)2019 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-31615004

RESUMO

Plant pathogens secrete proteins called effectors into the cells of their host to modulate the host immune response against colonization. Effectors can either modify or arrest host target proteins to sabotage the signaling pathway, and therefore are considered potential drug targets for crop disease control. In earlier research, the Xanthomonas type III effector XopAI was predicted to be a member of the arginine-specific mono-ADP-ribosyltransferase family. However, the crystal structure of XopAI revealed an altered active site that is unsuitable to bind the cofactor NAD+, but with the capability to capture an arginine-containing peptide from XopAI itself. The arginine peptide consists of residues 60 through 69 of XopAI, and residue 62 (R62) is key to determining the protein-peptide interaction. The crystal structure and the molecular dynamics simulation results indicate that specific arginine recognition is mediated by hydrogen bonds provided by the backbone oxygen atoms from residues W154, T155, and T156, and a salt bridge provided by the E265 sidechain. In addition, a protruding loop of XopAI adopts dynamic conformations in response to arginine peptide binding and is probably involved in target protein recognition. These data suggest that XopAI binds to its target protein by the peptide-binding ability, and therefore, it promotes disease progression. Our findings reveal an unexpected and intriguing function of XopAI and pave the way for further investigation on the role of XopAI in pathogen invasion.


Assuntos
ADP Ribose Transferases/química , Arginina/química , Peptídeos/química , Xanthomonas/química , ADP Ribose Transferases/genética , Sequência de Aminoácidos/genética , Arginina/genética , Domínio Catalítico/genética , Cristalografia por Raios X , Simulação de Dinâmica Molecular , Oxigênio/química , Peptídeos/genética , Plantas/genética , Plantas/microbiologia , Ligação Proteica , Conformação Proteica , Transdução de Sinais/genética , Xanthomonas/enzimologia , Xanthomonas/patogenicidade
12.
J Agric Food Chem ; 67(45): 12393-12401, 2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31596571

RESUMO

Accumulation of toxic copper in soil and development of copper-resistant pests are emerging challenges currently faced by the agricultural community worldwide. As an alternative, we have developed a ternary zinc chelate solution (TSOL) pesticide where zinc ions are the primary active ingredient. The material is composed of zinc, urea, and hydrogen peroxide. Urea was chosen as it is widely used as a plant fertilizer and can also bind to both zinc and hydrogen peroxide. No phytotoxicity was observed with TSOL on Meyer lemon (Citrus × meyeri) seedlings at a field spray rate of 800 µg/mL Zn metal concentration. Antimicrobial studies showed that TSOL exhibited improved killing efficacy against Escherichia coli and Xanthomonas alfalfae compared to Zn ions alone. Citrus canker field trials in a grapefruit (Chrysopelea paradisi) grove over three years showed that TSOL provided comparable disease protection to copper products at an equivalent or lower metal content.


Assuntos
Antibacterianos/química , Citrus/microbiologia , Peróxido de Hidrogênio/química , Doenças das Plantas/microbiologia , Ureia/química , Zinco/química , Zinco/farmacologia , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/crescimento & desenvolvimento , Peróxido de Hidrogênio/farmacologia , Folhas de Planta/microbiologia , Ureia/farmacologia , Xanthomonas/efeitos dos fármacos , Xanthomonas/crescimento & desenvolvimento
13.
Plant Sci ; 289: 110273, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31623772

RESUMO

The rice spotted leaf gene, OsSPL7, induces lesion mimic (LM) spots under heat stress. Herein, we provide several lines of evidence elucidating the importance of OsSPL7 in maintaining reactive oxygen species (ROS) balance via the regulation of downstream gene expression. osspl7 knockout (spl7ko) mutants showed LM and growth retardation. Transgenic rice lines strongly overexpressing OsSPL7 (SPL7OX-S) exhibited LM accompanied by accumulated H2O2, whereas moderate expressers of OsSPL7 (SPL7OX-M) did not, and neither of them exhibited severe growth defects. Transient expression of OsSPL7-GFP in rice protoplasts indicated that OsSPL7 localizes predominantly in the nucleus. Transcriptional activity assay suggested its function as a transcriptional activator in rice. Disease evaluation showed that both SPL7OX and spl7ko enhanced resistance to Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae, the causal agents of blast and blight diseases in rice, respectively. Additionally, SPL7OX enhanced tolerance to cold stress, whereas spl7ko showed a phenotype opposite to the overexpression lines. RNA sequencing analyses identified four major groups of differentially expressed genes associated with LM, pathogen resistance, LM-pathogen resistance, and potential direct targets of OsSPL7. Collectively, our results suggest that OsSPL7 plays a critical role in plant growth and balancing ROS during biotic and abiotic stress.


Assuntos
Regulação da Expressão Gênica de Plantas , Fatores de Transcrição de Choque Térmico/genética , Magnaporthe/fisiologia , Oryza/genética , Doenças das Plantas/imunologia , Espécies Reativas de Oxigênio/metabolismo , Xanthomonas/fisiologia , Resistência à Doença/genética , Fatores de Transcrição de Choque Térmico/metabolismo , Oryza/imunologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
14.
J Agric Food Chem ; 67(43): 11867-11876, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31584805

RESUMO

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv oryzae (Xoo) is considered as the most destructive disease of rice. The use of bactericides is among the most widely used traditional methods to control this destructive disease. The excessive and repeated use of the same bactericides is also becoming the reason behind the development of bactericide resistance. The widely used method for finding the new antimicrobial agents often involves the bacterial virulence factors as a target without affecting bacterial growth. Type III secretion system (T3SS) is a protein appendage and is considered as having essential virulence factors in most Gram-negative bacteria. Due to the conserved construct, T3SS has been regarded as an important mark for the blooming of novel antimicrobial drugs. Toward the search of new T3SS inhibitors, an alternative series of 1,3-thiazole derivatives were designed and synthesized. Their structures were characterized and confirmed by 1H NMR, 13C NMR, MS, and elemental analysis. All the title compounds inhibited the promoter activity of hpa1 gene significantly. Eight of them showed better inhibition than our previous T3SS inhibitor TS006 (o-coumaric acid, OCA). The treatment of Xoo with eight compounds significantly attenuated HR without affecting bacterial growth. The mRNA levels of some representative genes (hrp/hrc genes) were reduced up to different extents. In vivo bioassay results showed that eight T3SS inhibitors could reduce bacterial leaf blight and bacterial leaf streak symptoms on rice, significantly.


Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Furanos/farmacologia , Oryza/microbiologia , Doenças das Plantas/microbiologia , Sistemas de Secreção Tipo III/antagonistas & inibidores , Xanthomonas/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/química , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Furanos/química , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Sistemas de Secreção Tipo III/genética , Sistemas de Secreção Tipo III/metabolismo , Xanthomonas/genética , Xanthomonas/metabolismo
15.
Mol Plant Microbe Interact ; 32(12): 1577-1580, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31618137

RESUMO

The Xanthomonas genus, comprises more than 30 species of gram-negative bacteria, most of which are pathogens of plants with high economic value, such as rice, common bean, and maize. Transcription activator-like effectors (TALEs), which act by regulating the host gene expression, are some of the major virulence factors of these bacteria. We present a novel tool to identify TALE genes in the genome of Xanthomonas strains and their respective targets. The analysis of the results obtained by TargeTALE in a proof-of-concept validation demonstrate that, at optimum setting, approximately 93% of the predicted target genes with available expression data were confirmed as upregulated during the infection, indicating that the tool might be useful for researchers in the field.


Assuntos
Genoma Bacteriano , Efetores Semelhantes a Ativadores de Transcrição , Xanthomonas , Proteínas de Bactérias/genética , Interações Hospedeiro-Patógeno/genética , Oryza/microbiologia , Efetores Semelhantes a Ativadores de Transcrição/genética , Fatores de Virulência/genética , Xanthomonas/genética
17.
Nat Biotechnol ; 37(11): 1344-1350, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31659337

RESUMO

Bacterial blight of rice is an important disease in Asia and Africa. The pathogen, Xanthomonas oryzae pv. oryzae (Xoo), secretes one or more of six known transcription-activator-like effectors (TALes) that bind specific promoter sequences and induce, at minimum, one of the three host sucrose transporter genes SWEET11, SWEET13 and SWEET14, the expression of which is required for disease susceptibility. We used CRISPR-Cas9-mediated genome editing to introduce mutations in all three SWEET gene promoters. Editing was further informed by sequence analyses of TALe genes in 63 Xoo strains, which revealed multiple TALe variants for SWEET13 alleles. Mutations were also created in SWEET14, which is also targeted by two TALes from an African Xoo lineage. A total of five promoter mutations were simultaneously introduced into the rice line Kitaake and the elite mega varieties IR64 and Ciherang-Sub1. Paddy trials showed that genome-edited SWEET promoters endow rice lines with robust, broad-spectrum resistance.


Assuntos
Resistência à Doença , Proteínas de Membrana Transportadoras/genética , Oryza/crescimento & desenvolvimento , Efetores Semelhantes a Ativadores de Transcrição/genética , Xanthomonas/patogenicidade , Proteínas de Bactérias/genética , Sistemas CRISPR-Cas , Edição de Genes , Regulação da Expressão Gênica de Plantas , Mutação , Oryza/genética , Oryza/microbiologia , Proteínas de Plantas/genética , Regiões Promotoras Genéticas , Análise de Sequência de DNA , Xanthomonas/genética
18.
Nat Biotechnol ; 37(11): 1372-1379, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31659338

RESUMO

Blight-resistant rice lines are the most effective solution for bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo). Key resistance mechanisms involve SWEET genes as susceptibility factors. Bacterial transcription activator-like (TAL) effectors bind to effector-binding elements (EBEs) in SWEET gene promoters and induce SWEET genes. EBE variants that cannot be recognized by TAL effectors abrogate induction, causing resistance. Here we describe a diagnostic kit to enable analysis of bacterial blight in the field and identification of suitable resistant lines. Specifically, we include a SWEET promoter database, RT-PCR primers for detecting SWEET induction, engineered reporter rice lines to visualize SWEET protein accumulation and knock-out rice lines to identify virulence mechanisms in bacterial isolates. We also developed CRISPR-Cas9 genome-edited Kitaake rice to evaluate the efficacy of EBE mutations in resistance, software to predict the optimal resistance gene set for a specific geographic region, and two resistant 'mega' rice lines that will empower farmers to plant lines that are most likely to resist rice blight.


Assuntos
Resistência à Doença , Proteínas de Membrana Transportadoras/genética , Oryza/crescimento & desenvolvimento , Efetores Semelhantes a Ativadores de Transcrição/metabolismo , Xanthomonas/patogenicidade , Proteínas de Bactérias/genética , Sítios de Ligação , Sistemas CRISPR-Cas , Bases de Dados Genéticas , Edição de Genes , Regulação da Expressão Gênica de Plantas , Proteínas de Membrana Transportadoras/química , Proteínas de Membrana Transportadoras/metabolismo , Mutação , Oryza/genética , Oryza/microbiologia , Proteínas de Plantas/genética , Regiões Promotoras Genéticas , Análise de Sequência de DNA , Xanthomonas/metabolismo
19.
Pestic Biochem Physiol ; 160: 87-94, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31519261

RESUMO

Xanthomonas oryzae pv. oryzae (Xoo) infection directly leads to a severe disease known as leaf blight, which is a major cause of yield loss of rice. Use of traditional bactericides has resulted in severe resistance in pathogenic bacteria. A new approach screening compounds that target the virulence factors rather than killing bacterial pathogens is imperative. In gram-negative bacteria, the type III secretion system (T3SS) is a conserved and significant virulence factor considered as a target for drug development. Therefore, we designed and synthesized a new series of 5-phenyl-2-furan carboxylic acid derivatives stitched with 2-mercapto-1,3,4-thiadiazole. Bioassays revealed that the title candidates attenuated the hypersensitive response through suppressing the promoter activity of a harpin gene hpa1 without affecting bacterial growth. Quantitative real time polymerase chain reaction (qRT-PCR) analysis demonstrated reduced the expression of several genes associated with T3SS, when title compounds were applied. Additionally, hrp gene cluster members, including hrpG and hrpX, had reduced mRNA levels. In vivo greenhouse tests showed that candidate compounds could alleviate the effects of Xoo infection in rice (Oryza sativa) and possess better protective activity against rice bacterial leaf blight than bismerthiazol and thiodiazole copper. All tested compounds were safe to rice. This work suggests there are new safe options for Xoo control in rice from these 1,3,4-thiadiazole derivatives.


Assuntos
Tiadiazóis/síntese química , Tiadiazóis/farmacologia , Sistemas de Secreção Tipo III/efeitos dos fármacos , Xanthomonas/efeitos dos fármacos , Antibacterianos/farmacologia , Oryza/microbiologia
20.
J Biosci ; 44(4)2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31502560

RESUMO

Type-III (T3) effectors PthXo1 and AvrXa10 of Xanthomonas oryzae pv. oryzae are translocated into rice cells to induce virulence and avirulence on susceptible- and resistant-rice varieties Nipponbare and IRBB10, respectively. The translocation needs the bacterial T3 translocator Hpa1 and rice Oryza sativa plasma membrane protein OsPIP1;3. Here, we employed the beta-lactamase (BlaM) reporter system to observe PthXo1 and AvrXa10 translocation. The system was established to monitor effectors of animal-pathogenic bacteria by quantifying the BlaM hydrolysis product [P] and fluorescence resonance energy transfer (FRET) of the substrate. The feasibility of the BlaM reporter in rice protoplasts was evaluated by three criteria. The first criterion indicated differences between both [P] and FRET levels among wild types and OsPIP1;3-overexpressing and OsPIP1;3-silenced lines of both Nipponbare and IRBB10. The second criterion indicated differences between [P] and FRET levels in the presence and absence of Hpa1. The last criterion elucidated the coincidence of PthXo1 translocation with induced expression of the PthXo1 target gene in protoplasts of Nipponbare and the coincidence of AvrXa10 translocation with induced expression of the AvrXa10 target gene in protoplasts of IRBB10. These results provide an experimental avenue for real-time monitoring of bacterial T3 effector translocation into plant cells with a pathological consequence.


Assuntos
Oryza/genética , Doenças das Plantas/genética , Translocação Genética , Xanthomonas/genética , Transferência Ressonante de Energia de Fluorescência , Regulação da Expressão Gênica de Plantas/genética , Proteínas de Membrana/genética , Oryza/microbiologia , Doenças das Plantas/microbiologia , Protoplastos/microbiologia , Virulência/genética , Xanthomonas/patogenicidade , beta-Lactamases/genética
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