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1.
Int J Mol Sci ; 22(9)2021 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-34068779

RESUMO

Bacillus volatiles to control plant nematodes is a topic of great interest among researchers due to its safe and environmentally friendly nature. Bacillus strain GBSC56 isolated from the Tibet region of China showed high nematicidal activity against M. incognita, with 90% mortality as compared with control in a partition plate experiment. Pure volatiles produced by GBSC56 were identified through gas chromatography and mass spectrometry (GC-MS). Among 10 volatile organic compounds (VOCs), 3 volatiles, i.e., dimethyl disulfide (DMDS), methyl isovalerate (MIV), and 2-undecanone (2-UD) showed strong nematicidal activity with a mortality rate of 87%, 83%, and 80%, respectively, against M. incognita. The VOCs induced severe oxidative stress in nematodes, which caused rapid death. Moreover, in the presence of volatiles, the activity of antioxidant enzymes, i.e., SOD, CAT, POD, and APX, was observed to be enhanced in M. incognita-infested roots, which might reduce the adverse effect of oxidative stress-induced after infection. Moreover, genes responsible for plant growth promotion SlCKX1, SlIAA1, and Exp18 showed an upsurge in expression, while AC01 was downregulated in infested plants. Furthermore, the defense-related genes (PR1, PR5, and SlLOX1) in infested tomato plants were upregulated after treatment with MIV and 2-UD. These findings suggest that GBSC56 possesses excellent biocontrol potential against M. incognita. Furthermore, the study provides new insight into the mechanism by which GBSC56 nematicidal volatiles regulate antioxidant enzymes, the key genes involved in plant growth promotion, and the defense mechanism M. incognita-infested tomato plants use to efficiently manage root-knot disease.


Assuntos
Bacillus/genética , Resistência à Doença/genética , Lycopersicon esculentum/genética , Tylenchoidea/patogenicidade , Animais , Antinematódeos/metabolismo , Bacillus/metabolismo , China , Cromatografia Gasosa-Espectrometria de Massas , Lycopersicon esculentum/microbiologia , Lycopersicon esculentum/parasitologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Tylenchoidea/genética , Compostos Orgânicos Voláteis/metabolismo
2.
Int J Food Microbiol ; 348: 109224, 2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-33965694

RESUMO

ε-Poly-l-lysine (ε-PL) is a natural antimicrobial poly-cationic peptide widely applied as a natural preservative in the food industry, whereas its application in preventing postharvest loss of fruit was largely absent. This study investigated the antifungal activity of ε-PL and determined the possible mechanisms involved. The in vivo results indicated that 500 mg L-1 exogenous ε-PL treatment significantly inhibited black spot rot in apple, jujube, and tomato. The lesion diameter inhibition rate was range from 20.11% to 29.09% by 500 mg L-1 ε-PL treatment. ε-PL exerts antifungal activity against A. alternata in vitro, the half-inhibition concentration is 160.1 mg L-1. ε-PL induced morphology and ultrastructure change on the pathogen, which resulted in the inhibition of A. alternata. This was accomplished by disturbing pathogen membrane integrity and functionality. The fluorometric assay confirmed that ε-PL induced endogenous reactive oxygen species formation and accumulation in A. alternata and the elicited severe lipid peroxidation that caused membrane lesions. Further, ε-PL treatment enhanced the expression of genes involved in antioxidant metabolism and pathogenesis-related responses in apple fruit. These findings illustrated that ε-PL exhibits multifaceted antifungal activity by the direct effect on the pathogen as well as induce host defense responses. ε-PL may be conducive as a promising alternative for Alternaria rot management.


Assuntos
Alternaria/efeitos dos fármacos , Antifúngicos/farmacologia , Membrana Celular/efeitos dos fármacos , Frutas/microbiologia , Polilisina/farmacologia , Antioxidantes/metabolismo , Lycopersicon esculentum/microbiologia , Malus/microbiologia , Testes de Sensibilidade Microbiana , Ziziphus/microbiologia
3.
Ecotoxicol Environ Saf ; 217: 112268, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33930768

RESUMO

Cadmium (Cd) is among the most toxic heavy metals in soils. The ways by which tomato plants inoculated with a phosphate-solubilizing bacterium (PSB) respond to Cd and regulate gene expression remain unclear. We investigated hormone metabolism and genes involved in Cd resistance in tomato seedlings inoculated with the PSB strain N3. Cd inhibited tomato plant growth and nutrient uptake and increase in dry weight. Compared with Cd treatment, N3 inoculation inhibited the accumulation of Cd in the shoots and roots, and the root dry weight significantly increased by 30.50% (P < 0.05). The nitrogen and potassium contents in the roots of seedlings treated with N3 increased, and the phosphorus levels were the same as those in the control. N3 decreased the rate of Zn2+ absorption but increased Fe3+ absorption in the roots, and the amount of accumulated Cd increased with Zn2+ uptake. The concentrations of hormones (indole-3-acetic acid, IAA; zeatin, ZEA; and jasmonic acid, JA) increased under Cd stress, whereas inoculation with N3 reduced IAA and ZEA levels. In the comparison between N3 + Cd and Cd treatments, the highest number of up- and downregulated genes was obtained. Pathways involved in signaling response, photosynthesis, phenylpropanoid biosynthesis, and DNA replication and the photosynthesis-antenna proteins pathway play important roles in the responses and adaptation of seedlings to Cd. Inoculation with N3 alleviates Cd stress in tomato seedlings. The present study provides new insights into the differentially expressed genes related to interaction between PSB and tomato exposed to Cd in soils.


Assuntos
Burkholderia/fisiologia , Cádmio/toxicidade , Lycopersicon esculentum/fisiologia , Fosfatos/metabolismo , Poluentes do Solo/toxicidade , Cádmio/metabolismo , Expressão Gênica , Regulação da Expressão Gênica , Ácidos Indolacéticos , Lycopersicon esculentum/efeitos dos fármacos , Lycopersicon esculentum/microbiologia , Fotossíntese , Desenvolvimento Vegetal , Raízes de Plantas/metabolismo , Plântula/metabolismo , Solo , Poluentes do Solo/metabolismo
4.
Int J Food Microbiol ; 348: 109201, 2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-33930836

RESUMO

Salmonella enterica is frequently implicated in foodborne disease outbreaks associated with fresh-cut fruits. In the U.S., more than one third of fruit-related outbreaks have been linked to two S. enterica serotypes Newport and Typhimurium. Approximately 80% of fruit-related human salmonellosis cases were associated with tomatoes, cantaloupes and cucumbers. In this study, we investigated the population dynamics of S. Newport and S. Typhimurium on fresh-cut tomato, cantaloupe, cucumber and apple under short-term storage conditions. We further compared the transcriptomic profiles of a S. Newport strain on fresh-cut tomato and cantaloupe using high-throughput RNA-seq. We demonstrated that both S. enterica Newport and Typhimurium survived well on various fresh-cut fruit items under refrigeration storage conditions, independent of inoculation levels. However, S. enterica displayed variable survival behaviors on different types of fruits. For example, at 7 d storage, the population of S. enterica reduced less than 0.2 log (p > 0.05) on fresh-cut tomato and cantaloupe, in contrast to ~0.5 log (p < 0.05) on cucumber and apple. RNA-seq analysis suggested that S. enterica mediates its survival on fresh-cut fruits through differentially regulating genes involved in specific carbon utilization and metabolic pathways. Several known bacterial virulence factors (e.g., pag gene) were found to be differentially regulated on fresh-cut tomato and cantaloupe, suggesting a link between the events of food contamination and subsequent human infection. Findings from this study contribute to a better understanding of S. enterica survival mechanisms on fresh-cut produce.


Assuntos
Armazenamento de Alimentos/métodos , Doenças Transmitidas por Alimentos/microbiologia , Frutas/microbiologia , Infecções por Salmonella/transmissão , Salmonella enterica/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Cucumis melo/microbiologia , Cucumis sativus/microbiologia , Surtos de Doenças , Metabolismo Energético/genética , Contaminação de Alimentos , Microbiologia de Alimentos , Humanos , Lycopersicon esculentum/microbiologia , Malus/microbiologia , Infecções por Salmonella/microbiologia , Salmonella enterica/genética , Salmonella enterica/patogenicidade , Sorogrupo , Transcriptoma
5.
BMC Plant Biol ; 21(1): 183, 2021 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-33863284

RESUMO

BACKGROUND: PROTEIN PHOSPHATASE 2A (PP2A) expression is crucial for the symbiotic association between plants and various microbes, and knowledge on these symbiotic processes is important for sustainable agriculture. Here we tested the hypothesis that PP2A regulatory subunits, especially B'φ and B'θ, are involved in signalling between plants and mycorrhizal fungi or plant-growth promoting bacteria. RESULTS: Treatment of tomato plants (Solanum lycopersicum) with the plant growth-promoting rhizobacteria (PGPR) Azospirillum brasilense and Pseudomonas simiae indicated a role for the PP2A B'θ subunit in responses to PGPR. Arbuscular mycorrhizal fungi influenced B'θ transcript levels in soil-grown plants with canonical arbuscular mycorrhizae. In plant roots, transcripts of B'φ were scarce under all conditions tested and at a lower level than all other PP2A subunit transcripts. In transformed tomato plants with 10-fold enhanced B'φ expression, mycorrhization frequency was decreased in vermiculite-grown plants. Furthermore, the high B'φ expression was related to abscisic acid and gibberellic acid responses known to be involved in plant growth and mycorrhization. B'φ overexpressor plants showed less vigorous growth, and although fruits were normal size, the number of seeds per fruit was reduced by 60% compared to the original cultivar. CONCLUSIONS: Expression of the B'θ gene in tomato roots is strongly influenced by beneficial microbes. Analysis of B'φ overexpressor tomato plants and established tomato cultivars substantiated a function of B'φ in growth and development in addition to a role in mycorrhization.


Assuntos
Azospirillum brasilense/fisiologia , Lycopersicon esculentum/genética , Micorrizas/fisiologia , Proteínas de Plantas/genética , Proteína Fosfatase 2/genética , Pseudomonas/fisiologia , Simbiose/genética , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Proteínas de Plantas/metabolismo , Raízes de Plantas/microbiologia , Proteína Fosfatase 2/metabolismo , Transcrição Genética
6.
Int J Food Microbiol ; 347: 109196, 2021 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-33906045

RESUMO

Due to the recent outbreaks of Salmonella and Escherichia coli in fresh produce in the United States, the transfer of foodborne pathogens between animal feeding operations and fresh produce continues to be a considerable risk. The purpose of this study was to determine if the establishment of a vegetation barrier (VB) on small-scale sustainable farms could prevent the transmission of Salmonella and E. coli to nearby fresh produce fields. A 5-layer VB (31 × 49 m) was constructed between a dairy farm, a poultry farm, and a nearby produce field. Fresh produce (i.e., romaine lettuce and tomato), animal feces, and environmental (i.e., air, soil, and barrier) samples were collected for 15 months from 2018 to 2019. Four replicates of soil and fresh produce samples were taken from three plots located 10 m, 61 m, and 122 m away from the respective animal locations and processed for Salmonella and E. coli. Air and vegetative strip samples were sampled at 15-day intervals. Multiple colonies were processed from each positive sample, and a total of 143 positive Salmonella (n = 15) and E. coli (n = 128) isolates were retrieved from the soil, produce, air, and fecal samples. Interestingly, 18.2% of the Salmonella and E. coli isolates (n = 26) were recovered from fresh produce (n = 9) samples. Surprisingly, Salmonella isolates (n = 9) were only found in fecal (n = 3) samples collected from the dairy pasture. Data analysis suggests that the VB is an effective tool at reducing the transmission of E. coli and Salmonella from animal farms to fresh produce fields. However, based on phenotypic and genotypic testing, it is clear that fecal samples from animal farms are not the only source of pathogen contamination. This indicates that the environment (e.g., soil and wind), as well as the initial setup of the farm (e.g., proximity to service roads and produce plot placement), can contribute to the contamination of fresh produce. Our study recommends the need for more effective bioremediation and prevention control measures to use in conjunction with VBs to reduce pathogen transmission.


Assuntos
Infecções por Escherichia coli/transmissão , Escherichia coli/isolamento & purificação , Alface/microbiologia , Lycopersicon esculentum/microbiologia , Salmonelose Animal/transmissão , Salmonella/isolamento & purificação , Animais , Bovinos , Indústria de Laticínios , Escherichia coli/crescimento & desenvolvimento , Infecções por Escherichia coli/veterinária , Fazendas , Fezes/microbiologia , Aves Domésticas/microbiologia , Salmonella/crescimento & desenvolvimento
7.
Molecules ; 26(7)2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33804901

RESUMO

New strategies of control need to be developed with the aim of economic and environmental sustainability in plant and crop protection. Metabolomics is an excellent platform for both understanding the complex plant-pathogen interactions and unraveling new chemical control strategies. GC-MS-based metabolomics, along with a phytohormone analysis of a compatible and incompatible interaction between tomato plants and Fusarium oxysporum f. sp. lycopersici, revealed the specific volatile chemical composition and the plant signals associated with them. The susceptible tomato plants were characterized by the over-emission of methyl- and ethyl-salicylate as well as some fatty acid derivatives, along with an activation of salicylic acid and abscisic acid signaling. In contrast, terpenoids, benzenoids, and 2-ethylhexanoic acid were differentially emitted by plants undergoing an incompatible interaction, together with the activation of the jasmonic acid (JA) pathway. In accordance with this response, a higher expression of several genes participating in the biosynthesis of these volatiles, such as MTS1, TomloxC,TomloxD, and AOS, as well as JAZ7, a JA marker gene, was found to be induced by the fungus in these resistant plants. The characterized metabolome of the immune tomato plants could lead to the development of new resistance inducers against Fusarium wilt treatment.


Assuntos
Fusarium , Doenças das Plantas , Imunidade Vegetal , Proteínas de Plantas , Transdução de Sinais/imunologia , Fusarium/imunologia , Fusarium/metabolismo , Lycopersicon esculentum/imunologia , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/imunologia , Proteínas de Plantas/metabolismo
8.
Int J Mol Sci ; 22(8)2021 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-33920680

RESUMO

Late blight (LB) disease is a major threat to potato and tomato production. It is caused by the hemibiotrophic pathogen, Phytophthora infestans. P. infestans can destroy all of the major organs in plants of susceptible crops and result in a total loss of productivity. At the early pathogenesis stage, this hemibiotrophic oomycete pathogen causes an asymptomatic biotrophic infection in hosts, which then progresses to a necrotrophic phase at the later infection stage. In this study, to examine how the tomato proteome is regulated by P. infestans at different stages of pathogenesis, a data-independent acquisition (DIA) proteomics approach was used to trace the dynamics of the protein regulation. A comprehensive picture of the regulation of tomato proteins functioning in the immunity, signaling, defense, and metabolism pathways at different stages of P. infestans infection is revealed. Among the regulated proteins, several involved in mediating plant defense responses were found to be differentially regulated at the transcriptional or translational levels across different pathogenesis phases. This study increases understanding of the pathogenesis of P. infestans in tomato and also identifies key transcriptional and translational events possibly targeted by the pathogen during different phases of its life cycle, thus providing novel insights for developing a new strategy towards better control of LB disease in tomato.


Assuntos
Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/genética , Doenças das Plantas/genética , Proteoma/genética , Resistência à Doença , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Phytophthora/patogenicidade , Doenças das Plantas/microbiologia , Proteoma/metabolismo
9.
Mol Biol Rep ; 48(3): 3001-3006, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33687701

RESUMO

Tomato plants displaying early blight symptoms were collected from different localities in the provinces of Assiut and Sohag, Egypt. The causal pathogens were isolated on potato dextrose agar plates. Pathogenicity tests with 48 isolates were carried out under greenhouse conditions on tomato cultivar (CV 844). All tested isolates caused symptoms of early blight disease with different degrees. The highest disease severity on tomato plants was found after inoculation with isolate No. 6 followed by isolates No. 20 and No. 31. The most pathogenic isolates were identified by sequence analysis using ITS1 and ITS4 primers. The analysis of the amplified sequences from fungal isolates No. 6, 20 and 31 displayed 99-100% nucleotide identity with Alternaria solani, Curvularia lunata and A. alternata, respectively. To our knowledge, this is the first report of Curvularia lunata as one of the causal pathogens of early blight disease of tomato plants in Egypt.


Assuntos
Curvularia/patogenicidade , Lycopersicon esculentum/microbiologia , Doenças das Plantas/microbiologia , Alternaria/patogenicidade , Curvularia/isolamento & purificação , DNA Intergênico/genética , Egito , Funções Verossimilhança , Filogenia
10.
Int J Mol Sci ; 22(4)2021 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-33668636

RESUMO

Tomato is one of the major vegetable crops consumed worldwide. Tomato yellow leaf curl virus (TYLCV) and fungal Oidium sp. are devastating pathogens causing yellow leaf curl disease and powdery mildew. Such viral and fungal pathogens reduce tomato crop yields and cause substantial economic losses every year. Several commercial tomato varieties include Ty-5 (SlPelo) and Mildew resistance locus o 1 (SlMlo1) locus that carries the susceptibility (S-gene) factors for TYLCV and powdery mildew, respectively. The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) is a valuable genome editing tool to develop disease-resistant crop varieties. In this regard, targeting susceptibility factors encoded by the host plant genome instead of the viral genome is a promising approach to achieve pathogen resistance without the need for stable inheritance of CRISPR components. In this study, the CRISPR/Cas9 system was employed to target the SlPelo and SlMlo1 for trait introgression in elite tomato cultivar BN-86 to confer host-mediated immunity against pathogens. SlPelo-knockout lines were successfully generated, carrying the biallelic indel mutations. The pathogen resistance assays in SlPelo mutant lines confirmed the suppressed accumulation of TYLCV and restricted the spread to non-inoculated plant parts. Generated knockout lines for the SlMlo1 showed complete resistance to powdery mildew fungus. Overall, our results demonstrate the efficiency of the CRISPR/Cas9 system to introduce targeted mutagenesis for the rapid development of pathogen-resistant varieties in tomato.


Assuntos
Begomovirus/metabolismo , Sistemas CRISPR-Cas , Resistência à Doença/genética , Edição de Genes , Lycopersicon esculentum , Doenças das Plantas , Plantas Geneticamente Modificadas , Genoma de Planta , Lycopersicon esculentum/genética , Lycopersicon esculentum/crescimento & desenvolvimento , Lycopersicon esculentum/microbiologia , Lycopersicon esculentum/virologia , Doenças das Plantas/genética , Doenças das Plantas/microbiologia , Doenças das Plantas/virologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/crescimento & desenvolvimento , Plantas Geneticamente Modificadas/microbiologia , Plantas Geneticamente Modificadas/virologia
11.
Carbohydr Polym ; 260: 117799, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712147

RESUMO

Bacillus amyloliquefaciens strain PPL shows a potential for the control of phytopathogenic fungi. In the present study, upon growing the strain PPL on various forms of chitosan (0.5 % powder, 0.1 % soluble, and 0.15 % colloidal) as the carbon source, the antifungal activity on tomato Fusarium wilt correlated with the activity of chitosanase and ß-1,3-glucanase. The colloidal substrate-based strain PPL fermentation displayed the highest degree of spore germination inhibition (79.5 %) and biocontrol efficiency (76.0 %) in tomato by increased biofilm formation. The colloidal culture upregulated the expression of chitosanase gene (5.9-fold), and the powder attributed to the expression of cyclic lipopeptides-genes (2.5-5.7 fold). Moreover, the three chitosan cultures induced the morphological changes of Fusarium oxysporum. These results suggest that the choice of growth substrate synergistically affects the production of secondary metabolites by PPL strain, and consequently its antifungal activity.


Assuntos
Quitosana/química , Polímeros/química , Antifúngicos/metabolismo , Antifúngicos/farmacologia , Bacillus amyloliquefaciens/enzimologia , Bacillus amyloliquefaciens/crescimento & desenvolvimento , Bacillus amyloliquefaciens/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Técnicas de Cultura Celular por Lotes , Biofilmes , Fusarium/efeitos dos fármacos , Glicosídeo Hidrolases/genética , Glicosídeo Hidrolases/metabolismo , Lipopeptídeos/metabolismo , Lycopersicon esculentum/microbiologia
12.
Int J Food Microbiol ; 342: 109092, 2021 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-33607541

RESUMO

Tomato is widely consumed and marketed as juice, puree, or fresh product. Nevertheless, 30% of its harvest volume is lost because of the fungus Alternaria alternata. This research aimed to provide early detection methods for this fungal decay on tomato juice and fresh fruit. Biomass content, CO2, O2 and volatile compounds (VOCs) during A. alternata growth in tomato juice and fruit at two ripening stages (breaker and red colour) were evaluated. Additionally, CO2 and VOCs data set were analysed with a hierarchical cluster technique (HCA) to explore the differences between inoculated and non-inoculated samples. Biomass was determined by gravimetry, CO2 and O2 by gas chromatography (GC), and VOCs by GC-mass spectrometry. Biomass content was not drastically modified by tomato's ripening stage (3-6 mg of dry weight). CO2 in tomato juice was considerably higher in the inoculated samples with A. alternata (27-63%) than in the non-inoculated ones (2.8-6.6%), regardless of the ripeness stage; while in tomato fruit CO2 was higher at breaker stage and inoculated with A. alternata (33-41%) than the remaining treatments (9-23%). It was also observed that, except for limonene, trans-sabinene hydrate, and rhodovibrin, VOCs' release during the interaction between tomato juice and A. alternata was different from the fresh tomato and A. alternata interaction. Only the HCA based on CO2 data showed clear differences between the inoculated and non-inoculated tomato juice and fruit at both ripening stages.


Assuntos
Alternaria/isolamento & purificação , Sucos de Frutas e Vegetais/microbiologia , Frutas/microbiologia , Lycopersicon esculentum/microbiologia , Alternaria/metabolismo , Biomassa , Dióxido de Carbono/análise , Dióxido de Carbono/metabolismo , Microbiologia de Alimentos , Frutas/química , Sucos de Frutas e Vegetais/análise , Compostos Orgânicos Voláteis/análise , Compostos Orgânicos Voláteis/metabolismo
13.
Appl Environ Microbiol ; 87(6)2021 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-33397695

RESUMO

Inoculation studies are important when assessing microbial survival and growth in food products. These studies typically involve the pregrowth of multiple strains of a target pathogen under a single condition; this emphasizes strain diversity. To gain a better understanding of the impacts of strain diversity ("nature") and pregrowth conditions ("nurture") on subsequent bacterial growth in foods, we assessed the growth and survival of Salmonella enterica (n = 5), Escherichia coli (n = 6), and Listeria (n = 5) inoculated onto tomatoes, precut lettuce, and cantaloupe rind, respectively. Pregrowth conditions included (i) 37°C to stationary phase (baseline), (ii) low pH, (iii) high salt, (iv) reduced water activity, (v) log phase, (vi) minimal medium, and (vii) 21°C. Inoculated tomatoes were incubated at 21°C; lettuce and cantaloupe were incubated at 7°C. Bacterial counts were assessed over three phases, including initial reduction (phase 1), change in bacterial numbers over the first 24 h of incubation (phase 2), and change over the 7-day incubation (phase 3). E. coli showed overall decline in counts (<1 log) over the 7-day period, except for a <1-log increase after pregrowth in high salt and to mid-log phase. In contrast, S. enterica and Listeria showed regrowth after an initial reduction. Pregrowth conditions had a substantial and significant effect on all three phases of S. enterica and E. coli population dynamics on inoculated produce, whereas strain did not show a significant effect. For Listeria, both pregrowth conditions and strain affected changes in phase 2 but not phases 1 and 3.IMPORTANCE Our findings suggest that inclusion of multiple pregrowth conditions in inoculation studies can best capture the range of growth and survival patterns expected for Salmonella enterica and Escherichia coli present on produce. This is particularly important for fresh and fresh-cut produce, where stress conditions encountered by pathogens prior to contamination can vary widely, making selection of a typical pregrowth condition virtually impossible. Pathogen growth and survival data generated using multiple pregrowth conditions will allow for more robust microbial risk assessments that account more accurately for uncertainty.


Assuntos
Cucumis melo/microbiologia , Escherichia coli/crescimento & desenvolvimento , Alface/microbiologia , Listeria/crescimento & desenvolvimento , Lycopersicon esculentum/microbiologia , Salmonella enterica/crescimento & desenvolvimento , Contagem de Colônia Microbiana , Microbiologia de Alimentos
14.
J Exp Bot ; 72(7): 2696-2709, 2021 03 29.
Artigo em Inglês | MEDLINE | ID: mdl-33462583

RESUMO

The increased susceptibility of ripe fruit to fungal pathogens poses a substantial threat to crop production and marketability. Here, we coupled transcriptomic analyses with mutant studies to uncover critical processes associated with defense and susceptibility in tomato (Solanum lycopersicum) fruit. Using unripe and ripe fruit inoculated with three fungal pathogens, we identified common pathogen responses reliant on chitinases, WRKY transcription factors, and reactive oxygen species detoxification. We established that the magnitude and diversity of defense responses do not significantly impact the interaction outcome, as susceptible ripe fruit mounted a strong immune response to pathogen infection. Then, to distinguish features of ripening that may be responsible for susceptibility, we utilized non-ripening tomato mutants that displayed different susceptibility patterns to fungal infection. Based on transcriptional and hormone profiling, susceptible tomato genotypes had losses in the maintenance of cellular redox homeostasis, while jasmonic acid accumulation and signaling coincided with defense activation in resistant fruit. We identified and validated a susceptibility factor, pectate lyase (PL). CRISPR-based knockouts of PL, but not polygalacturonase (PG2a), reduced susceptibility of ripe fruit by >50%. This study suggests that targeting specific genes that promote susceptibility is a viable strategy to improve the resistance of tomato fruit against fungal disease.


Assuntos
Lycopersicon esculentum , Doenças das Plantas , Imunidade Vegetal , Botrytis , Frutas/imunologia , Frutas/microbiologia , Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/genética , Lycopersicon esculentum/imunologia , Lycopersicon esculentum/microbiologia , Doenças das Plantas/imunologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
15.
J Agric Food Chem ; 69(3): 913-921, 2021 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-33464897

RESUMO

Although bacteria with 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity have been used to mitigate biotic and abiotic stresses in crops, it is not well known whether the ACC deaminase gene (acdS) in Pseudomonas azotoformans is related to the alleviation of salt stress by the bacterium. This study aimed to evaluate the effects of acdS in P. azotoformans strain CHB 1107 on the nutrient uptake and growth of tomato plants under salt stress. The acdS mutant (CHB 1107 M) of P. azotoformans CHB 1107 was obtained through bacterial conjugation. Wild-type (CHB 1107 WT) and CHB 1107 M were used to inoculate tomato plants grown in a soil or solution with an electrical conductivity of 6 dS/m adjusted by NaCl. CHB 1107 M completely lost the ability to produce ACC deaminase, whereas the complementation of acdS in CHB 1107 M preserved its ACC deaminase activity. CHB 1107 WT significantly reduced the production of ethylene and proline by tomato plants under salt stress, increasing the shoot and root dry weights of tomato plants compared with the noninoculated control and CHB 1107 M. In addition, tomato plants inoculated with CHB 1107 M showed a significant reduction in K (27.5%), Ca (23.0%), and Mn uptake (17.5%) compared with those inoculated with CHB 1107 WT. In contrast, CHB 1107 WT significantly reduced Na uptake by tomato plants in comparison to CHB 1107 M in saline soil conditions. In addition, the inoculation of tomato plants with CHB 1107 WT resulted in a higher K/Na ratio than in those inoculated with CHB 1107 M and the noninoculated control. These findings suggest that acdS in P. azotoformans is associated with the amelioration of salinity stress in tomato. Plant transformation with acdS and the field application of P. azotoformans may be used as potential management tools for crops under salt stress.


Assuntos
Proteínas de Bactérias/metabolismo , Carbono-Carbono Liases/metabolismo , Lycopersicon esculentum/metabolismo , Pseudomonas/enzimologia , Cloreto de Sódio/metabolismo , Proteínas de Bactérias/genética , Carbono-Carbono Liases/genética , Lycopersicon esculentum/microbiologia , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Pseudomonas/genética , Pseudomonas/metabolismo , Estresse Salino , Microbiologia do Solo
16.
Plant Cell Physiol ; 62(2): 306-320, 2021 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-33386853

RESUMO

The formation of arbuscular mycorrhizal (AM) symbiosis requires plant root host cells to undergo major structural and functional reprogramming to house the highly branched AM fungal structure for the reciprocal exchange of nutrients. These morphological modifications are associated with cytoskeleton remodelling. However, molecular bases and the role of microtubules (MTs) and actin filament dynamics during AM formation are largely unknown. In this study, the tomato tsb (tomato similar to SB401) gene, belonging to a Solanaceae group of genes encoding MT-associated proteins (MAPs) for pollen development, was found to be highly expressed in root cells containing arbuscules. At earlier stages of mycorrhizal development, tsb overexpression enhanced the formation of highly developed and transcriptionally active arbuscules, while tsb silencing hampers the formation of mature arbuscules and represses arbuscule functionality. However, at later stages of mycorrhizal colonization, tsb overexpressing (OE) roots accumulate fully developed transcriptionally inactive arbuscules, suggesting that the collapse and turnover of arbuscules might be impaired by TSB accumulation. Imaging analysis of the MT cytoskeleton in cortex root cells OE tsb revealed that TSB is involved in MT bundling. Taken together, our results provide unprecedented insights into the role of novel MAP in MT rearrangements throughout the different stages of the arbuscule life cycle.


Assuntos
Lycopersicon esculentum/metabolismo , Microtúbulos/fisiologia , Micorrizas/crescimento & desenvolvimento , Proteínas de Plantas/fisiologia , Genes de Plantas/genética , Genes de Plantas/fisiologia , Lycopersicon esculentum/genética , Lycopersicon esculentum/microbiologia , Lycopersicon esculentum/fisiologia , Microtúbulos/metabolismo , Filogenia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Raízes de Plantas/fisiologia , Alinhamento de Sequência , Simbiose
17.
Arch Microbiol ; 203(4): 1383-1397, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33386869

RESUMO

The endophytic microbiome uses mechanisms such as the secretion of diffusible antibiotic molecules, synthesis and release of volatile organic compounds, and/or toxins to protect plants. The aim of this research was to study the volatile organic compounds (VOCs) profile as well as the diffusible secondary metabolites produced and released by endophytic bacteria isolated from tomato plants that in in-vitro assays prevented growth of pathogenic fungi. Bacteria belonging to seven genera (Acinetobacter, Arthrobacter, Bacillus, Microbacterium, Pantoea, Pseudomonas, and Stenotrophomonas) were isolated from different tissues of tomato plants with and without symptoms of Gray leaf spot, a disease provoked by Stemphylium lycopersici. In vitro, antagonistic assays were performed and the effect of volatile and soluble compounds released by endophytic bacteria on the growth of pathogenic fungi was determined. The VOCs synthesized by the endophytes were extracted, identified and quantified. These isolates representatives of seven bacterial genera inhibited the growth of three fungal pathogens of tomato S. lycopersici, Alternaria alternata and Corynespora cassiicola, which was related to the synthesis of soluble compounds as well as VOCs. Endophytes synthesize and release different VOCs, probably due to the different type of interaction that each bacterium establishes with the fungus, presenting a range of fungal growth inhibition.


Assuntos
Antivirais/farmacologia , Bactérias/metabolismo , Endófitos/metabolismo , Lycopersicon esculentum/microbiologia , Compostos Orgânicos Voláteis/farmacologia , Antibiose , Antivirais/isolamento & purificação , Antivirais/metabolismo , Bactérias/classificação , Bactérias/isolamento & purificação , Endófitos/classificação , Endófitos/isolamento & purificação , Fungos/efeitos dos fármacos , Fungos/crescimento & desenvolvimento , Controle Biológico de Vetores , Doenças das Plantas/microbiologia , Doenças das Plantas/prevenção & controle , Compostos Orgânicos Voláteis/isolamento & purificação , Compostos Orgânicos Voláteis/metabolismo
18.
Arch Virol ; 166(2): 651-654, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33387023

RESUMO

A novel lytic bacteriophage, Ralstonia phage RP13, was isolated from tomato fields in Pang Nga, Thailand. Electron microscopic observation showed it to have the features of a myovirus with a novel triangulation number (T = 21, dextro). The RP13 DNA appeared to be heavily modified. By applying RNA sequencing and RNA-sequence-mediated DNA sequencing, the whole genome of RP31 was determined to be 170,942 bp in length with a mean G+C content of 39.2%. A total of 277 ORFs were identified as structural, functional, or hypothetical genes in addition to four tRNA genes. Phylogenetic analysis suggested that RP13 is not closely related to any other known phages. Thus, we concluded that the RP13 is a novel phage infecting R. solanacearum strains and will be a useful biocontrol agent against bacterial wilt disease.


Assuntos
Bacteriófagos/genética , Genoma Viral/genética , Doenças das Plantas/microbiologia , Ralstonia solanacearum/virologia , Composição de Bases/genética , Genômica/métodos , Especificidade de Hospedeiro/genética , Lycopersicon esculentum/microbiologia , Fases de Leitura Aberta/genética , Filogenia , RNA de Transferência/genética , Tailândia
19.
Plant Sci ; 302: 110702, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33288015

RESUMO

Pseudomonas syringae pv. tomato (Pst) is a pathogenic microorganism that causes bacterial speck disease and affects tomato yield and quality. Pto is a disease resistant gene for plant to recognize and defense against Pst. Pto interacts with Pti (Pto interacting) proteins, which include three transcription factors, Pti4, Pti5, Pti6, and they were thought to be downstream of Pto-mediated pathway to promote the expression of disease-related genes. In the present work, the overexpression plants of Pti4, Pti5 or Pti6 were obtained by Agrobacterium-mediated transformation in tomato. The Pti4/5/6-overexpressed lines indicated enhanced expression of pathogenesis-related genes and resistance to pathogenic bacteria Pst DC3000. Meanwhile, the transgenic plants showed that Pti4/5/6 function in ripening but performed no obvious adverse influence on flowering time, seed-setting rate, weight and soluble solids content of fruits. Furthermore, Pti-overexpressed fruits exhibited increased enzymatic activities of phenylalnine ammonialyase, catalase, peroxidase and decreased content of malondialdehyde. Additionally, cell-free and in vivo ubiquitination assay indicated that Pti4, Pti5 and Pti6 degraded by 26S proteasome which suggested that these Pti transcription regulators' functions could be regulated by ubiquitin-mediated post translational regulation in tomato.


Assuntos
Resistência à Doença , Frutas/crescimento & desenvolvimento , Lycopersicon esculentum/fisiologia , Doenças das Plantas/imunologia , Proteínas de Plantas/fisiologia , Pseudomonas syringae , Fatores de Transcrição/fisiologia , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/crescimento & desenvolvimento , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/microbiologia , Doenças das Plantas/microbiologia , Proteínas de Plantas/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Fatores de Transcrição/metabolismo , Ubiquitinação
20.
Food Microbiol ; 94: 103631, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33279063

RESUMO

We aimed to study the efficacy of a water-assisted UVC light device (WUVC) as an innovative clean technology for the disinfection of fresh sound tomatoes and processing wash water and water turbidity was evaluated as a critical parameter. First, wash waters with different turbidities (from 0.4 to 828 NTU) were inoculated with Listeria innocua and treated in the WUVC device at different dosages. Secondly, fresh tomatoes, inoculated with L. innocua and non-inoculated ones, were treated using the WUVC device containing wash water of different turbidities for different times. The reduction of L. innocua populations on wash water and on the surface of tomato was influenced by turbidity; lower reduction values were observed at higher turbidities. Washing tomatoes with tap water with UVC lamps off (control treatment, TW) decreased L. innocua population on the surface of tomatoes but did not eliminate those bacteria that went into the water. Contrarily, when UVC lights were on, L. innocua population in wash water after treatment significantly decreased, those in clean water being the lowest populations. Reductions of native microbiota on the clean water treated with the highest UV-C radiation dose were lower than those obtained when tomatoes were artificially inoculated. We demonstrated that high reductions of L. innocua population on fresh tomatoes could be achieved using the WUVC system but some drawbacks related to the increase of turbidity should be solved for its implementation in real conditions.


Assuntos
Desinfecção/métodos , Irradiação de Alimentos/métodos , Listeria/efeitos da radiação , Lycopersicon esculentum/microbiologia , Contagem de Colônia Microbiana , Desinfecção/instrumentação , Frutas/microbiologia , Listeria/crescimento & desenvolvimento , Raios Ultravioleta , Água/química
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