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1.
Gene ; 746: 144652, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32259631

RESUMO

Circular RNAs (circRNAs), a novel branch of noncoding RNAs, are widespread in eukaryotic cells. Particularly, due to their abilities to bind microRNA (miRNA) and serve as "sponges", circRNAs can regulate gene expression and participate in multiple biological processes. To detect the function of the circRNAs in tomato resistance, in our study, high-throughput sequencing were used to detect the circRNAs in tomatoes before and after Phytophthora infestans (P. infestans) infection. A total of 68 circRNAs were identified, of them, 18 (26%) were termed as exonic circRNAs, 33 (49%) were termed as intergenic circRNAs, 17 (25%) were termed as intronic circRNAs. Thirty-six out of 68 circRNAs differentially expressed in tomatoes after infection, including 9 up- and 27 down-regulated. Among the up-regulated circRNAs, two exoinc circRNAs, circRNA45 and circRNA47 were annotated as whitefly-induced gp91-phox and ethylene-forming enzyme, respectively. Both of them could act as miR477-3p sponge. Transgenic plants transiently overexpressed circRNA45 and circRNA47 both displayed smaller lesion area than the control plants upon infection, accompanied by lower expression levels of miR477-3p. Furthermore, transiently overexpression of miR477-3p in tomatoes leading to a decline in their targeted disease related genes expression. Our results firstly identified circRNAs in tomato upon P. infestans infection and demonstrated that circRNA45 and circRNA47 may act as positive regulators in tomato resistance by regulating miRNA-mRNAs expression levels.


Assuntos
Resistência à Doença/genética , Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum , Phytophthora infestans , Doenças das Plantas , RNA Circular , RNA de Plantas , Lycopersicon esculentum/genética , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , MicroRNAs/biossíntese , MicroRNAs/genética , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , RNA Circular/biossíntese , RNA Circular/genética , RNA de Plantas/biossíntese , RNA de Plantas/genética
2.
Can J Microbiol ; 66(6): 401-412, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32160477

RESUMO

Fusarium wilt is a devastating soil-borne disease mainly caused by highly host-specific formae speciales of Fusarium spp. Antagonistic microorganisms play a very important role in Fusarium wilt control. Isolation of potential biocontrol strains has become increasingly important. Bacterial strain SEM-2 was isolated from the high-temperature stage of silkworm excrement composting. SEM-2 exhibited a considerable antagonistic effect against Fusarium graminearum mycelial growth and spore germination. The results of pot experiments suggested that SEM-2 has a better inhibitory effect on the early stage of disease occurrence. The green fluorescent protein labelled SEM-2 coated on the surface of tomato seeds colonised the roots of tomato plants in 15 days. Genome sequencing identified SEM-2 as a new strain of Bacillus subtilis, and genome annotation and analysis determined gene clusters related to the biosynthesis of antimicrobials, such as bacillaene, fengycin, bacillibactin, subtilosin A, surfactin, and bacilysin. Interestingly, liquid chromatography - quadrupole time-of-flight mass spectrometry revealed that metabolites in pathways associated with the synthesis of secondary metabolites and antibiotics were highly differentially expressed. These findings may help to explain the mode of action of B. subtilis SEM-2 against Fusarium spp.


Assuntos
Antibiose , Bacillus subtilis/fisiologia , Bombyx/microbiologia , Fusarium/crescimento & desenvolvimento , Genoma Bacteriano/genética , Lycopersicon esculentum/microbiologia , Doenças das Plantas/prevenção & controle , Animais , Anti-Infecciosos/metabolismo , Bacillus subtilis/química , Bacillus subtilis/genética , Bacillus subtilis/isolamento & purificação , Agentes de Controle Biológico , Cromatografia Líquida , Fezes/microbiologia , Espectrometria de Massas , Família Multigênica/genética , Doenças das Plantas/microbiologia , Sementes/microbiologia
3.
Int J Food Microbiol ; 321: 108542, 2020 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-32066036

RESUMO

Members of the Bacillus cereus group are common contaminants of vegetables. One potential source of contamination is the application of B. thuringiensis based biopesticides. Although evidence of the presence of biopesticidal strains on food products is scarce, this information is essential for assessing potential risks associated with the application of these biopesticides. In order to contribute to knowledge about the presence of biopesticidal B. thuringiensis strains in foodstuffs, we investigated the occurrence of B. thuringiensis on tomatoes and bell pepper. We analyzed 99 samples of fresh bell pepper for B. cereus group members, while 426 samples of tomatoes were tested by the competent food control laboratories of the federal states in Germany. The isolates recovered from these samples were further characterized in terms of their capability to produce parasporal crystals as well as enterotoxins. A possible correlation between the B. thuringiensis isolates and biopesticidal strains was investigated by multilocus sequence typing (MLST) and whole genome Single Nucleotide Polymorphism (wgSNP) analyses. The prevalence of B. cereus group members was 41% for bell pepper and 28% for tomato samples. Isolates recovered from these samples were dominated by B. thuringiensis (93% and 99%, respectively). All B. thuringiensis isolates carried the enterotoxin genes nheA, hblD and cytK-2. In a subset of 83 B. thuringiensis isolates analyzed by MLST, 99% of the isolates matched the sequence types (ST) 8 and 15, which are also shared by the biopesticidal strains B. thuringiensis kurstaki ABTS-351 and B. thuringiensis aizawai ABTS-1857. Of the 82 isolates assigned to ST 8 or ST 15, a selection of 42 isolates was further characterized by wgSNP analysis. Of these, seven isolates differed from strain ABTS-351 by ≤4 core SNPs and 18 isolates differed from strain ABTS-1857 by ≤2 core SNPs, indicating a relationship of these isolates with the respective biopesticidal strain. These isolates originated from samples with maximum colony counts of 5.3 × 103 cfu/g for bell pepper and 1.0 × 105 cfu/g for tomatoes.


Assuntos
Bacillus thuringiensis/isolamento & purificação , Agentes de Controle Biológico/análise , Capsicum/microbiologia , Lycopersicon esculentum/microbiologia , Bacillus cereus/classificação , Bacillus cereus/genética , Bacillus cereus/isolamento & purificação , Bacillus thuringiensis/classificação , Bacillus thuringiensis/genética , Enterotoxinas/genética , Microbiologia de Alimentos , Alemanha , Humanos , Tipagem de Sequências Multilocus
4.
PLoS One ; 15(2): e0228936, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32084150

RESUMO

A total of fifteen potential methyl t-butyl ether (MtBE)-degrading bacterial strains were isolated from contaminated soil. They have been identified as belonging to the genera Bacillus, Pseudomonas, Kocuria, Janibacter, Starkeya, Bosea, Mycolicibacterium, and Rhodovarius. Bacillus aryabhattai R1B, S. novella R8b, and M. mucogenicum R8i were able to grow using MtBE as carbon source, exhibiting different growth behavior and contaminant degradation ability. Their biocontrol ability was tested against various fungal pathogens. Both S. novella R8b and B. aryabhattai were effective in reducing the development of necrotic areas on leaves within 48 hours from Botritys cinerea and Alternaria alternata inoculation. Whereas, M. mucogenicum effectively controlled B. cinerea after 72 hours. Similar results were achieved using Pythium ultimum, in which the application of isolated bacteria increased seed germination. Only M. mucogenicum elicited tomato plants resistance against B. cinerea. This is the first report describing the occurrence of bioremediation and biocontrol activities in M. mucogenicum, B. aryabhattai and S. novella species. The production of maculosin and its antibiotic activity against Rhizoctonia solani has been reported for first time from S. novella. Our results highlight the importance of multidisciplinary approaches to achieve a consistent selection of bacterial strains useful for plant protection and bioremediation purposes.


Assuntos
Bactérias/isolamento & purificação , Biodegradação Ambiental , Éteres Metílicos/toxicidade , Alphaproteobacteria/isolamento & purificação , Alphaproteobacteria/metabolismo , Bacillus/isolamento & purificação , Bacillus/metabolismo , Bactérias/metabolismo , Lycopersicon esculentum/microbiologia , Éteres Metílicos/química , Mycobacteriaceae/isolamento & purificação , Mycobacteriaceae/metabolismo , Doenças das Plantas/microbiologia , Rhizoctonia/crescimento & desenvolvimento , Solo , Microbiologia do Solo
5.
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
6.
PLoS One ; 15(1): e0227422, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31923250

RESUMO

Studies of the interactions between plants and their microbiome have been conducted worldwide in the search for growth-promoting representative strains for use as biological inputs for agriculture, aiming to achieve more sustainable agriculture practices. With a focus on the isolation of plant growth-promoting (PGP) bacteria with ability to alleviate N stress, representative strains that were found at population densities greater than 104 cells g-1 and that could grow in N-free semisolid media were isolated from soils under different management conditions and from the roots of tomato (Solanum lycopersicum) and lulo (Solanum quitoense) plants that were grown in those soils. A total of 101 bacterial strains were obtained, after which they were phylogenetically categorized and characterized for their basic PGP mechanisms. All strains belonged to the Proteobacteria phylum in the classes Alphaproteobacteria (61% of isolates), Betaproteobacteria (19% of isolates) and Gammaproteobacteria (20% of isolates), with distribution encompassing nine genera, with the predominant genus being Rhizobium (58.4% of isolates). Strains isolated from conventional horticulture (CH) soil composed three bacterial genera, suggesting a lower diversity for the diazotrophs/N scavenger bacterial community than that observed for soils under organic management (ORG) or secondary forest coverture (SF). Conversely, diazotrophs/N scavenger strains from tomato plants grown in CH soil comprised a higher number of bacterial genera than did strains isolated from tomato plants grown in ORG or SF soils. Furthermore, strains isolated from tomato were phylogenetically more diverse than those from lulo. BOX-PCR fingerprinting of all strains revealed a high genetic diversity for several clonal representatives (four Rhizobium species and one Pseudomonas species). Considering the potential PGP mechanisms, 49 strains (48.5% of the total) produced IAA (2.96-193.97 µg IAA mg protein-1), 72 strains (71.3%) solubilized FePO4 (0.40-56.00 mg l-1), 44 strains (43.5%) solubilized AlPO4 (0.62-17.05 mg l-1), and 44 strains produced siderophores (1.06-3.23). Further, 91 isolates (90.1% of total) showed at least one PGP trait, and 68 isolates (67.3%) showed multiple PGP traits. Greenhouse trials using the bacterial collection to inoculate tomato or lulo plants revealed increases in plant biomass (roots, shoots or both plant tissues) elicited by 65 strains (54.5% of the bacterial collection), of which 36 were obtained from the tomato rhizosphere, 15 were obtained from the lulo rhizosphere, and 14 originated from samples of soil that lacked plants. In addition, 18 strains showed positive inoculation effects on both Solanum species, of which 12 were classified as Rhizobium spp. by partial 16S rRNA gene sequencing. Overall, the strategy adopted allowed us to identify the variability in the composition of culturable diazotroph/N-scavenger representatives from soils under different management conditions by using two Solanum species as trap plants. The present results suggest the ability of tomato and lulo plants to enrich their belowground microbiomes with rhizobia representatives and the potential of selected rhizobial strains to promote the growth of Solanum crops under limiting N supply.


Assuntos
Bactérias/isolamento & purificação , Fixação de Nitrogênio/fisiologia , Rizosfera , Microbiologia do Solo , Solanum/microbiologia , Fenômenos Fisiológicos Bacterianos , Biodiversidade , Produtos Agrícolas/crescimento & desenvolvimento , Lycopersicon esculentum/microbiologia , Microbiota , Nitrogênio/metabolismo , Desenvolvimento Vegetal , Proteobactérias/isolamento & purificação , Solanum/genética , Especificidade da Espécie
7.
Environ Pollut ; 259: 113893, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31918147

RESUMO

Phoxim, a broad-spectrum organophosphate pesticide, is widely used in agriculture to control insect pests in vegetable crops as well as in farm mammals. However, the indiscriminate use of phoxim has increased its release into the environment, leading to the contamination of plant-based foods such as vegetables. In this study, we investigated the effect of Trichoderma asperellum (TM, an opportunistic fungus) on phoxim residue in tomato roots and explored the mechanisms of phoxim metabolism through analysis of detoxification enzymes and gene expression. Degradation kinetics of phoxim showed that TM inoculation rapidly and significantly reduced phoxim residues in tomato roots. Phoxim concentrations at 5d, 10d and 15d post treatment were 75.12, 65.71 and 77.45% lower in TM + phoxim than only phoxim treatment, respectively. The TM inoculation significantly increased the glutathione (GSH) content, the activity of glutathione S-transferase (GST) and the transcript levels of GSH, GST1, GST2 and GST3 in phoxim-treated roots. In addition, the activity of peroxidase and polyphenol peroxidase involved in the xenobiotic conversion also increased in TM + phoxim treatment. The expression of detoxification genes, such as CYP724B2, GR, ABC2 and GPX increased by 3.82, 3.08, 7.89 and 2.46 fold, respectively in TM + phoxim compared with only phoxim. Similarly, the content of ascorbate (AsA) and the ratio of AsA to dehydroascorbate increased by 45.16% and 57.34%, respectively in TM + phoxim-treated roots. Our results suggest that TM stimulates plant detoxification potential in all three phases (conversion, conjugation and sequestration) of xenobiotc metabolism, leading to a reduced phoxim residue in tomato roots.


Assuntos
Lycopersicon esculentum , Compostos Organotiofosforados , Resíduos de Praguicidas , Raízes de Plantas , Trichoderma , Animais , Recuperação e Remediação Ambiental , Lycopersicon esculentum/microbiologia , Compostos Organotiofosforados/análise , Compostos Organotiofosforados/metabolismo , Resíduos de Praguicidas/análise , Resíduos de Praguicidas/metabolismo , Raízes de Plantas/química , Raízes de Plantas/microbiologia , Trichoderma/metabolismo
8.
PLoS One ; 15(1): e0221604, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31961875

RESUMO

Phytophthora infestans (Mont.) de Bary, a hemibiotrophic oomycete, has caused severe epidemics of late blight in tomato and potato crops around the world since the Irish Potato Famine in the 1840s. Breeding of late blight resistant cultivars is one of the most effective strategies to overcome this disruptive disease. However, P. infestans is able to break down host resistance and acquire resistance to various fungicides, possibly because of the existence of high genetic variability among P. infestans isolates via sexual and asexual reproduction. Therefore, to manage this disease, it is important to understand the genetic divergence of P. infestans isolates. In this study, we analyzed the genomes of P. infestans isolates collected from Egypt and Japan using various molecular approaches including the mating type assay and genotyping simple sequence repeats, mitochondria DNA, and effector genes. We also analyzed genome-wide single nucleotide polymorphisms using double-digest restriction-site associated DNA sequencing and whole genome resequencing (WGRS). The isolates were classified adequately using high-resolution genome-wide approaches. Moreover, these analyses revealed new clusters of P. infestans isolates in the Egyptian population. Monitoring the genetic divergence of P. infestans isolates as well as breeding of resistant cultivars would facilitate the elimination of the late blight disease.


Assuntos
Genes Fúngicos Tipo Acasalamento/genética , Sequenciamento de Nucleotídeos em Larga Escala , Phytophthora infestans/genética , Doenças das Plantas/microbiologia , DNA Mitocondrial/genética , Fungicidas Industriais/farmacologia , Genótipo , Lycopersicon esculentum/microbiologia , Repetições de Microssatélites/genética , Phytophthora infestans/crescimento & desenvolvimento , Doenças das Plantas/genética , Análise de Sequência de DNA , Solanum tuberosum/microbiologia
9.
J Agric Food Chem ; 68(7): 1986-1997, 2020 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-31986044

RESUMO

In this study, the impact of cerium oxide nanoparticles on the nutritional value of tomato (Solanum lycopersicum) fruit grown in soil infested with Fusarium oxysporum f. sp. lycopersici was investigated in a greenhouse pot study. Three-week old seedlings of Bonny Best tomato plants were exposed by foliar and soil routes to nanoparticle CeO2 (NP CeO2) and cerium acetate (CeAc) at 0, 50, and 250 mg/L and transplanted into pots containing a soil mixture infested with the Fusarium wilt pathogen. Fruit biomass, water content, diameter, and nutritional content (lycopene, reducing and total sugar) along with elemental composition, including Ce, were evaluated. Fruit Ce concentration was below the detection limit in all treatments. Foliar exposure to NP CeO2 at 250 increased the fruit dry weight (67%) and lycopene content (9%) in infested plants, compared with the infested untreated control. Foliar exposure to CeAc at 50 mg/L reduced fruit fresh weight (46%) and water content (46%) and increased the fruit lycopene content by 11% via root exposure as compared with the untreated infested control. At 250 mg/L, CeAc increased fruit dry weight (94%), compared with the infested untreated control. Total sugar content decreased in fruits of infested plants exposed via roots to NP CeO2 at 50 mg/kg (63%) and 250 mg/kg (54%), CeAc at 50 mg/kg (46%), and foliarly at 50 mg/L (50%) and 250 mg/L (50%), all compared with the infested untreated control. Plants grown in Fusarium-infested soil had decreased fruit dry weight (42%) and lycopene content (17%) and increased total sugar (60%) and Ca content (140%), when compared with the noninfested untreated control (p ≤ 0.05). Overall, the data suggested minimal negative effects of NP CeO2 on the nutritional value of tomato fruit while simultaneously suppressing Fusarium wilt disease.


Assuntos
Cério/farmacologia , Frutas/química , Fungicidas Industriais/farmacologia , Fusarium/fisiologia , Lycopersicon esculentum/microbiologia , Doenças das Plantas/microbiologia , Frutas/efeitos dos fármacos , Frutas/crescimento & desenvolvimento , Frutas/microbiologia , Fusarium/efeitos dos fármacos , Lycopersicon esculentum/química , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/crescimento & desenvolvimento , Nanopartículas/química , Valor Nutritivo , Solo/química , Microbiologia do Solo
10.
Food Microbiol ; 87: 103359, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31948614

RESUMO

Washing in chlorinated water is widely practiced for commercial fresh produce processing. While known as an effective tool for mitigating food safety risks, chlorine washing could also represent an opportunity for spreading microbial contaminations under sub-optimal operating conditions. This study evaluated Salmonella inactivation and cross-contamination in a simulated washing process of cherry and grape tomatoes. Commercially harvested tomatoes and the associated inedible plant matter (debris) were differentially inoculated with kanamycin resistant (KanR) or rifampin resistant (RifR) Salmonella strains, and washed together with uninoculated tomatoes in simulated packinghouse dump tank (flume) wash water. Washing in chlorinated water resulted in significantly higher Salmonella reduction on tomatoes than on debris, achieving 2-3 log reduction on tomatoes and about 1 log reduction on debris. Cross-contamination by Salmonella on tomatoes was significantly reduced in the presence of 25-150 mg/L free chlorine, although sporadic cross-contamination on tomatoes was detected when tomatoes and debris were inoculated at high population density. The majority of the sporadic cross-contaminations originated from Salmonella inoculated on debris. These findings suggested that debris could be a potentially significant source of contamination during commercial tomato washing.


Assuntos
Contaminação de Alimentos/análise , Lycopersicon esculentum/microbiologia , Prunus avium/microbiologia , Salmonella/crescimento & desenvolvimento , Cloro/farmacologia , Manipulação de Alimentos , Microbiologia de Alimentos , Inocuidade dos Alimentos , Salmonella/efeitos dos fármacos
11.
BMC Plant Biol ; 20(1): 33, 2020 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-31959099

RESUMO

BACKGROUND: Leaf mold disease caused by Cladosporium fulvum is a serious threat affecting the global production of tomato. Cf genes are associated with leaf mold resistance, including Cf-16, which confers effective resistance to leaf mold in tomato. However, the molecular mechanism of the Cf-16-mediated resistance response is largely unknown. RESULTS: We performed a comparative transcriptome analysis of C. fulvum-resistant (cv. Ontario7816) and C. fulvum-susceptible (cv. Moneymaker) tomato cultivars to identify differentially expressed genes (DEGs) at 4 and 8 days post inoculation (dpi) with C. fulvum. In total, 1588 and 939 more DEGs were found in Cf-16 tomato than in Moneymaker at 4 and 8 dpi, respectively. Additionally, 1350 DEGs were shared between the 4- and 8-dpi Cf-16 groups, suggesting the existence of common core DEGs in response to C. fulvum infection. The up-regulated DEGs in Cf-16 tomato were primarily associated with defense processes and phytohormone signaling, including salicylic acid (SA) and jasmonic acid (JA). Moreover, SA and JA levels were significantly increased in Cf-16 tomato at the early stages of C. fulvum infection. Contrary to the previous study, the number of up-regulated genes in Cf-16 compared to Cf-10 and Cf-12 tomatoes was significantly higher at the early stages of C. fulvum infection. CONCLUSION: Our results provide new insight into the Cf-mediated mechanism of resistance to C. fulvum, especially the unique characteristics of Cf-16 tomato in response to this fungus.


Assuntos
Cladosporium/fisiologia , Lycopersicon esculentum/genética , Doenças das Plantas/genética , Proteínas de Plantas/genética , Perfilação da Expressão Gênica , Lycopersicon esculentum/microbiologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/metabolismo
12.
Physiol Plant ; 168(1): 98-117, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31017672

RESUMO

WRKY transcription factors play a key role in the tolerance of biotic and abiotic stresses across various crop species, but the function of some WRKY genes, particularly in tomato, remains unexplored. Here, we characterize the roles of a previously unstudied WRKY gene, SlWRKY8, in the resistance to pathogen infection and the tolerance to drought and salt stresses. Expression of SlWRKY8 was up-regulated upon Pseudomonas syringae pv. tomato DC3000 (Pst. DC3000), abiotic stresses such as drought, salt and cold, as well as ABA and SA treatments. The SlWRKY8 protein was localized to the nucleus with no transcription activation in yeast, but it could activate W-box-dependent transcription in plants. The overexpression of SlWRKY8 in tomato conferred a greater resistance to the pathogen Pst. DC3000 and resulted in the increased transcription levels of two pathogen-related genes SlPR1a1 and SlPR7. Moreover, transgenic plants displayed the alleviated wilting or chlorosis phenotype under drought and salt stresses, with higher levels of stress-induced osmotic substances like proline and higher transcript levels of the stress-responsive genes SlAREB, SlDREB2A and SlRD29. Stomatal aperature was smaller under drought stress in transgenic plants, maintaining higher water content in leaves compared with wild-type plants. The oxidative pressure, indicated by the concentration of hydrogen peroxide (H2 O2 ) and malondialdehyde (MDA), was also reduced in transgenic plants, where we also observed higher levels of antioxidant enzyme activities under stress. Overall, our results suggest that SlWRKY8 functions as a positive regulator in plant immunity against pathogen infection as well as in plant responses to drought and salt stresses.


Assuntos
Resistência à Doença , Secas , Lycopersicon esculentum/genética , Doenças das Plantas/genética , Proteínas de Plantas/genética , Salinidade , Fatores de Transcrição/genética , Regulação da Expressão Gênica de Plantas , Humanos , Lycopersicon esculentum/microbiologia , Doenças das Plantas/microbiologia , Imunidade Vegetal , Plantas Geneticamente Modificadas , Estresse Fisiológico
13.
Proc Natl Acad Sci U S A ; 117(2): 1148-1159, 2020 01 14.
Artigo em Inglês | MEDLINE | ID: mdl-31806755

RESUMO

There is increasing interest in the plant microbiome as it relates to both plant health and agricultural sustainability. One key unanswered question is whether we can select for a plant microbiome that is robust after colonization of target hosts. We used a successive passaging experiment to address this question by selecting upon the tomato phyllosphere microbiome. Beginning with a diverse microbial community generated from field-grown tomato plants, we inoculated replicate plants across 5 plant genotypes for 4 45-d passages, sequencing the microbial community at each passage. We observed consistent shifts in both the bacterial (16S amplicon sequencing) and fungal (internal transcribed spacer region amplicon sequencing) communities across replicate lines over time, as well as a general loss of diversity over the course of the experiment, suggesting that much of the naturally observed microbial community in the phyllosphere is likely transient or poorly adapted within the experimental setting. We found that both host genotype and environment shape microbial composition, but the relative importance of genotype declines through time. Furthermore, using a community coalescence experiment, we found that the bacterial community from the end of the experiment was robust to invasion by the starting bacterial community. These results highlight that selecting for a stable microbiome that is well adapted to a particular host environment is indeed possible, emphasizing the great potential of this approach in agriculture and beyond. In light of the consistent response of the microbiome to selection in the absence of reciprocal host evolution (coevolution) described here, future studies should address how such adaptation influences host health.


Assuntos
Genótipo , Lycopersicon esculentum/microbiologia , Microbiota/fisiologia , Adaptação Fisiológica , Bactérias/classificação , Bactérias/genética , Lycopersicon esculentum/genética , Lycopersicon esculentum/crescimento & desenvolvimento , Microbiota/genética , Filogenia , RNA Ribossômico 16S/genética
14.
Food Chem ; 310: 125827, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31734011

RESUMO

Pathogenic fungi cause enormous losses to fruits, and ethylene (ET) is associated with disease development in fruit crops. In this study, ET production of several fungal pathogens was enhanced by light, probably through the free radicals produced by photochemical reactions. Real-time gas analysis showed a sharp increase in ET production when fungal cultures were moved from dark-to-light (DTL). Similarly, light accelerated ET production in the Botrytis cinerea-infected Arabidopsis thaliana plants even when pyrazinamide, the inhibitor for plant ET synthesis, was applied, suggesting that the fungus is responsible for ET production during host invasion. Furthermore, a sharp increase in ET production after DTL transition was observed in B. cinerea-infected tomatoes and grapes, but not in healthy or physically wounded fruits. Taken together, these findings indicate that the DTL-induced ET is specific to the plant materials with fungal infection, and thus represents a candidate marker for non-destructive disease diagnosis of harvested fruits.


Assuntos
Etilenos/biossíntese , Microbiologia de Alimentos/métodos , Frutas/microbiologia , Fungos/patogenicidade , Doenças das Plantas/microbiologia , Arabidopsis/microbiologia , Botrytis/metabolismo , Botrytis/patogenicidade , Cromatografia Gasosa , Etilenos/análise , Interações Hospedeiro-Patógeno , Luz , Lycopersicon esculentum/microbiologia , Vitis/microbiologia
15.
Arch Microbiol ; 202(2): 257-267, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31605156

RESUMO

Pseudomonas chlororaphis ToZa7 is a promising biocontrol agent possessing valuable characteristics and reducing disease severity caused by Fusarium oxysporum f. sp. radicis-lycopersici (Forl) in tomato. In this study, the strain's ability to induce three pathogenesis-related (PR) genes (PR-1a, GLUA, and CHI3) in tomato, was studied using quantitative reverse transcription PCR. The genes PR-1a and GLUA were up-regulated after 120 h exposure to P. chororaphis ToZa7 (15.22- and 13.11-fold, respectively), as compared to the untreated control, without challenge inoculation by the pathogen. To study the effects of individual or combined application of P. chororaphis ToZa7 and the compatible biocontrol fungus Clonostachys rosea IK726, challenged with the pathogen, the expression patterns of the above three PR genes were monitored, in tomato roots. Expression of PR1-a was noteworthy, especially 48 h after challenge inoculation, when C. rosea IK726 alone or in combination with P. chororaphis, ToZa7 was pre-inoculated on tomato roots (38.53-fold and 53.74-fold, respectively). Expression of PR1-a, 72 h after challenge inoculation, was the highest in P. chororaphis ToZa7, among biocontrol treatments. Expression of CHI3 was much lower, while up-regulation of GLUA was overall not observed. Confocal laser scanning microscopy of intact tomato roots and bacterial counts of superficially disinfected roots revealed, for the first time, that P. chororaphis ToZa7 colonizes the exterior as well as the internal tissues.


Assuntos
Agentes de Controle Biológico/metabolismo , Hypocreales/metabolismo , Lycopersicon esculentum/microbiologia , Doenças das Plantas/prevenção & controle , Pseudomonas chlororaphis/metabolismo , Fusarium/patogenicidade , Lycopersicon esculentum/genética , Doenças das Plantas/microbiologia , Raízes de Plantas/microbiologia
16.
Food Chem ; 310: 125901, 2020 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31816533

RESUMO

The mechanism of SlMYC2, involved in methyl jasmonate (MJ)-induced tomato fruit resistance to pathogens, was investigated. The data indicated that MJ treatment enhanced the accumulation of total phenolics and flavonoids, as well as individual phenolic acids and flavonoids, which might be caused by the increased phenylalanine ammonia-lyase and polyphenol oxidase activities, induced pathogenesis-related gene (PR) expression, ß-1,3-glucanase and chitinase activities, as well as α-tomatine, by inducing GLYCOALKALOID METABOLISM gene expression. These effects, induced by MJ, partly contributed to tomato fruit resistance to Botrytis cinerea. Nevertheless, the induction effects of MJ were almost counteracted by silence of SlMYC2, and the disease incidence and lesion diameter in MJ + SlMYC2-silenced fruit were higher than those in MJ-treated fruit. These observations are the first evidence that SlMYC2 plays vital roles in MJ-induced fruit resistance to Botrytis cinerea, possibly by regulating defence enzyme activities, SlPRs expression, α-tomatine, special phenolic acids and flavonoid compounds.


Assuntos
Acetatos/metabolismo , Botrytis/patogenicidade , Ciclopentanos/metabolismo , Lycopersicon esculentum/microbiologia , Oxilipinas/metabolismo , Proteínas de Plantas/genética , Acetatos/farmacologia , Ciclopentanos/farmacologia , Resistência à Doença/fisiologia , Flavonoides/metabolismo , Frutas/efeitos dos fármacos , Frutas/microbiologia , Frutas/fisiologia , Regulação da Expressão Gênica de Plantas , Interações Hospedeiro-Patógeno , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/fisiologia , Oxilipinas/farmacologia , Fenilalanina Amônia-Liase/metabolismo , Doenças das Plantas/microbiologia , Proteínas de Plantas/metabolismo , Tomatina/análogos & derivados , Tomatina/metabolismo
17.
Insect Sci ; 27(1): 58-68, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29676854

RESUMO

"Candidatus Liberibacter solanacearum" (Lso) are phloem-restricted and unculturable Gram-negative bacteria. Presently five haplotypes have been identified worldwide; but only haplotypes A and B are associated with the vector Bactericera cockerelli (Sulc.) in the Americas. Previous studies showed that Lso-infection reduces B. cockerelli reproductive output and that Lso haplotype B is more pathogenic than Lso haplotype A. To understand the interaction of Lso haplotype B and B. cockerelli, the fitness of Lso-free and Lso B-infected insects, and the expression of vitellogenin (BcVg1-like), a gene involved directly in the insect reproduction were analyzed. Statistical differences in the number of eggs oviposited, and the total number of progeny nymphs and adults were found among crosses of insects with or without Lso. Significant differences in sex proportions were found between Lso B-infected and Lso-free crosses: a higher proportion of F1 adult females were obtained from Lso B-infected mothers. A significant reduction of BcVg1-like was observed in crosses performed with Lso B-infected females compared to the Lso-free insects. In female cohorts of different age, a significant reduction of BcVg1-like expression was measured in 7-d-old Lso B-infected females (virgin and mated) compared with 7-d-old Lso-free females (virgin and mated), respectively. The reduction of BcVg1-like transcript was associated with a lower number of developing oocytes observed in female's reproductive systems. Overall, this study represents the first step to understand the interaction of Lso B with B. cockerelli, highlighting the effect of Lso B infection on egg production, BcVg1-like expression, and oocyte development.


Assuntos
Aptidão Genética , Hemípteros/fisiologia , Rhizobiaceae/fisiologia , Vitelogênese , Animais , Hemípteros/genética , Hemípteros/crescimento & desenvolvimento , Hemípteros/microbiologia , Lycopersicon esculentum/microbiologia , Lycopersicon esculentum/fisiologia , Ninfa/genética , Ninfa/crescimento & desenvolvimento , Ninfa/microbiologia , Ninfa/fisiologia , Doenças das Plantas/microbiologia
18.
Int J Food Microbiol ; 312: 108387, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31669763

RESUMO

Fresh produce-associated outbreaks of foodborne illnesses continue to occur every year in the U.S., suggesting limitations of current practices and the need for effective intervention technologies. Advanced oxidation process involves production of hydrogen radicals, which are the strongest oxidant. The objective of the present study was to evaluate the effectiveness of advanced oxidation process by combining gaseous ozone and aerosolized hydrogen peroxide. Grape tomatoes were inoculated with a 2-strain cocktail of Salmonella typhimurium on both stem scar and smooth surface. Gaseous ozone (800 and 1600 ppm) and aerosolized hydrogen peroxide (2.5, 5 and 10%) were separately or simultaneously introduced into a treatment chamber where the inoculated tomatoes were placed. During the 30 min treatments, hydrogen peroxide was aerosolized using an atomizer operated in two modes: continuously or 15 s on/50 s off. After the treatments, surviving Salmonella on the smooth surface and stem scar were enumerated. Results showed that ozone alone reduced Salmonella populations by <0.6 log CFU/fruit on both the smooth surface and the stem scar area, and aerosolized hydrogen peroxide alone reduced the populations by up to 2.1 log CFU/fruit on the smooth surface and 0.8 log CFU/fruit on stem scar area. However, the combination treatments reduced the populations by up to 5.2 log CFU/fruit on smooth surface and 4.2 log CFU/fruit on the stem scar. Overall, our results demonstrate that gaseous ozone and aerosolized hydrogen peroxide have synergistic effects on the reduction of Salmonella populations on tomatoes.


Assuntos
Doenças Transmitidas por Alimentos/prevenção & controle , Peróxido de Hidrogênio/farmacologia , Lycopersicon esculentum/microbiologia , Ozônio/farmacologia , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Microbiologia de Alimentos/métodos , Frutas/microbiologia , Oxirredução
19.
Plant Sci ; 290: 110289, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31779900

RESUMO

Botrytis cinerea is a major plant pathogen, causing losses in crops during growth and storage. Here we show that increased accumulation of phenylalanine (Phe) and Phe-derived metabolites in plant leaves significantly reduces their susceptibility to B. cinerea. Arabidopsis, petunia and tomato plants were enriched with Phe by either overexpressing a feedback-insensitive E.coli DAHP synthase (AroG*), or by spraying or drenching detached leaves or whole plants with external Phe, prior to infection with B. cinerea. Metabolic analysis of Arabidopsis and petunia plants overexpressing AroG* as well as wt petunia plants treated externally with Phe, revealed an increase in Phe-derived phenylpropanoids accumulated in their leaves, and specifically in those inhibiting B. cinerea germination and growth, suggesting that different compounds reduce susceptibility to B. cinerea in different plants. Phe itself had no inhibitory effect on germination or growth of B. cinerea, and inhibition of Phe metabolism in petunia plants treated with external Phe prevented decreased susceptibility to the fungus. Thus, Phe metabolism into an array of metabolites, unique to each plant and plant organ, is the most probable cause for increased resistance to Botrytis. This mechanism may provide a basis for ecologically friendly control of a wide range of plant pathogens.


Assuntos
Arabidopsis/química , Botrytis/fisiologia , Lycopersicon esculentum/química , Petunia/química , Fenilalanina/metabolismo , Doenças das Plantas/microbiologia , Arabidopsis/microbiologia , Suscetibilidade a Doenças , Lycopersicon esculentum/microbiologia , Petunia/microbiologia , Folhas de Planta/química , Folhas de Planta/microbiologia
20.
Plant Sci ; 290: 110274, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31779908

RESUMO

Plants are exposed to a vast array of pathogens. The interaction between them may be classified in compatible and incompatible. Polyamines (PAs) are involved in defense responses, as well as salicylic acid (SA), gentisic acid (GA) and nitric oxide (NO), which can increase the content of reactive oxygen species (ROS), creating a harsh environment to the pathogen. ROS can also damage the host cell and they can be controlled by ascorbate and glutathione. Among phytopathogens, one of the major threats to tomato crops is tomato mottle mosaic virus (ToMMV). Resistance against this virus probably involves the Tm-22 gene. This work aimed to analyze signaling and antioxidant molecules in the defense response against ToMMV in Solanum pimpinellifolium and in S. lycopersicum 'VFNT'. In S. pimpinellifolium plants inoculated with ToMMV, an increase in NO, SA, GA, ascorbate and oxidized glutathione and a decrease in the content of PAs were observed. Characteristic symptoms of diseased plants and high absorbance values in PTA-ELISA indicated a compatible interaction. In VFNT-inoculated plants, less significant differences were noticed. Symptoms and viral concentration were not detected, indicating an incompatible interaction, possibly associated with the effector-triggered immunity (ETI) response.


Assuntos
Antioxidantes/metabolismo , Doenças das Plantas/microbiologia , Solanum/metabolismo , Tobamovirus/fisiologia , Gentisatos/metabolismo , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Óxido Nítrico/metabolismo , Poliaminas/metabolismo , Ácido Salicílico/metabolismo , Transdução de Sinais , Solanum/microbiologia
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