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1.
Aquat Toxicol ; 226: 105559, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32652412

RESUMO

High nitrate (NO3--N) concentration is a growing aquatic risk concern worldwide. However, adverse effects of high NO3--N concentration on submerged macrophytes-epiphytic biofilms are unclear. In this study, the alterations in physiological changes, biofilms formation and chemical compositions were investigated on leaves of Vallisneria asiatica exposed to different NO3--N concentrations. The findings showed that 10 mg L-1NO3--N resulted in low photosynthetic efficiency by inhibiting chlorophyll content 26.2 % and decreased intrinsic efficiency of photosystem II significantly at 14th day post treatment. Malondialdehyde, several antioxidant enzyme activities (i.e., superoxide dismutase, peroxidase and catalase), and secondary metabolites (i.e., phenolic compounds and anthocyanin) were all significantly up-regulated with 10 mg L-1NO3--N, implied oxidative stress were stimulated. However, no significant alterations in these indicators were observed with 5 mg L-1NO3--N. Compared to control, 10 mg L-1NO3--N concentration significantly stimulated microbes growth in biofilm and reduced the roughness of leaf-biofilms surface, but it had little effect on the biofilms distribution (from single clone to blocks) as revealed by scanning electron microscope and multifractal analysis. Results from X-ray photoelectron spectroscopy analysis showed that the percentage of P, Cl, K and the ratio of O1 (-O-) /O2 (C = O) were higher in leaves of control than treatments with 10 mg L-1NO3--N, indicating that 10 mg L-1NO3--N concentration exhibited significant inhibition of chemical activity and nutrient uptake of the leaf surfaces. Overall, these results demonstrated that high NO3--N does stimulate the biofilm growth and can cause negative impacts on submerged macrophytes growth.


Assuntos
Biofilmes/crescimento & desenvolvimento , Hydrocharitaceae/efeitos dos fármacos , Nitratos/toxicidade , Estresse Oxidativo/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Biofilmes/efeitos dos fármacos , Catalase/metabolismo , Clorofila/metabolismo , Hydrocharitaceae/crescimento & desenvolvimento , Hydrocharitaceae/metabolismo , Hydrocharitaceae/microbiologia , Malondialdeído/metabolismo , Peroxidases/metabolismo , Fotossíntese/efeitos dos fármacos , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Folhas de Planta/microbiologia , Superóxido Dismutase/metabolismo
2.
Plant Mol Biol ; 104(1-2): 113-136, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32627097

RESUMO

KEY MESSAGE: Present study revealed a complex relationship among histone H3 methylation (examined using H3K4/K27me3 marks), cytosine DNA methylation and differential gene expression during Lr28 mediated leaf rust resistance in wheat. During the present study, genome-wide histone modifications were examined in a pair of near isogenic lines (NILs) (with and without Lr28 in the background of cv. HD2329). The two histone marks used included H3K4me3 (an activation mark) and H3K27me3 (a repression mark). The results were compared with levels of expression (using RNA-seq) and DNA methylation (MeDIP) data obtained using the same pair of NILs. Some of the salient features of the present study include the following: (i) large scale differential binding sites (DBS) were available for only H3K4me3 in the susceptible cultivar, but for both H3K4me3 and H3K27me3 in its resistant NIL; (ii) DBSs for H3K27me3 mark were more abundant (> 80%) in intergenic regions, whereas DBSs for H3K4me3 were distributed in all genomic regions including exons, introns, intergenic, TTS (transcription termination sites) and promoters; (iii) fourteen (14) genes associated with DBSs showed co-localization for both the marks; (iv) only a small fraction (7% for H3K4me3 and 12% for H3K27me3) of genes associated with DBSs matched with the levels of gene expression inferred from RNA-seq data; (v) validation studies using qRT-PCR were conducted on 26 selected representative genes; results for only 11 genes could be validated. The proteins encoded by important genes involved in promoting infection included domains generally carried by R gene proteins such as Mlo like protein, protein kinases and purple acid phosphatase. Similarly, proteins encoded by genes involved in resistance included those carrying domains for lectin kinase, R gene, aspartyl protease, etc. Overall, the results suggest a very complex network of downstream genes that are expressed during compatible and incompatible interactions; some of the genes identified during the present study may be used in future validation studies involving RNAi/overexpression approaches.


Assuntos
Basidiomycota/metabolismo , Resistência à Doença/genética , Genes de Plantas/genética , Genoma de Planta/genética , Histonas/genética , Doenças das Plantas/genética , Triticum/genética , Triticum/metabolismo , Imunoprecipitação da Cromatina , Metilação de DNA , Regulação da Expressão Gênica de Plantas , Ligação Genética , Histonas/metabolismo , Anotação de Sequência Molecular , Doenças das Plantas/microbiologia , Folhas de Planta/genética , Folhas de Planta/microbiologia , Regiões Promotoras Genéticas , Reprodutibilidade dos Testes , Alinhamento de Sequência , Análise de Sequência , Análise de Sequência de RNA , Transcrição Genética , Triticum/microbiologia
3.
PLoS One ; 15(7): e0235918, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32645090

RESUMO

Leaves of lettuce, pepper, tomato and grapevine plants grown in greenhouse conditions were exposed to UV-C light for either 60 s or 1 s, using a specific LEDs-based device, and wavelengths and energy were the same among different light treatments. Doses of UV-C light that both effectively stimulated plant defences and were innocuous were determined beforehand. Tomato plants and lettuce plants were inoculated with Botrytis cinerea, pepper plants with Phytophthora capsici, and grapevine with Plasmopara viticola. In some experiments we investigated the effect of a repetition of treatments over periods of several days. All plants were inoculated 48 h after exposure to the last UV-C treatment. Lesions on surfaces were measured up to 12 days after inoculation, depending on the experiment and the pathogen. The results confirmed that UV-C light stimulates plant resistance; they show that irradiation for one second is more effective than irradiation for 60 s, and that repetition of treatments is more effective than single light treatments. Moreover a systemic effect was observed in unexposed leaves that were close to exposed leaves. The mechanisms of perception and of the signalling and metabolic pathways triggered by flashes of UV-C light vs. 60 s irradiation exposures are briefly discussed, as well as the prospects for field use of UV-C flashes in viticulture and horticulture.


Assuntos
Alface/efeitos da radiação , Lycopersicon esculentum/efeitos da radiação , Piper/efeitos da radiação , Raios Ultravioleta , Botrytis/patogenicidade , Clorofila/química , Alface/microbiologia , Lycopersicon esculentum/microbiologia , Redes e Vias Metabólicas/efeitos dos fármacos , Phytophthora/patogenicidade , Piper/parasitologia , Doenças das Plantas/microbiologia , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controle , Folhas de Planta/microbiologia , Folhas de Planta/parasitologia , Folhas de Planta/efeitos da radiação , Transdução de Sinais/efeitos dos fármacos
4.
PLoS Genet ; 16(7): e1008713, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32658889

RESUMO

Thaumatin-like proteins (TLPs), which are defined as pathogenesis-related protein family 5 (PR5) members, are common plant proteins involved in defense responses and confer antifungal activity against many plant pathogens. Our earlier studies have reported that the TaTLP1 gene was isolated from wheat and proved to be involved in wheat defense in response to leaf rust attack. The present study aims to identify the interacting proteins of TaTLP1 and characterize the role of the interaction between wheat and Puccinia triticina (Pt). Pull-down experiments designed to isolate the molecular target of TaTLP1 in tobacco resulted in the identification of TaPR1, a pathogenesis-related protein of family 1, and the interaction between TaTLP1 and TaPR1 was confirmed by yeast two-hybrid experiments (Y2H), bimolecular fluorescence complementation (BiFC), and co-immunoprecipitation (Co-IP). In vitro, TaTLP1 and TaPR1 together increased antifungal activity against Pt. In vivo, the disease resistance phenotype, histological observations of fungal growth and host responses, and accumulation of H2O2 in TaTLP1-TaPR1 in co-silenced plants indicated that co-silencing significantly enhanced wheat susceptibility compared to single knockdown TaTLP1 or TaPR1 plants. The accumulation of reactive oxygen species (ROS) was significantly reduced in co-silenced plants compared to controls during Pt infection, which suggested that the TaTLP1-TaPR1 interaction positively modulates wheat resistance to Pt in an ROS-dependent manner. Our findings provide new insights for understanding the roles of two different PRs, TaTLP1 and TaPR1, in wheat resistance to leaf rust.


Assuntos
Antígenos de Plantas/genética , Resistência à Doença/genética , Doenças das Plantas/genética , Proteínas de Plantas/genética , Triticum/genética , Basidiomycota/genética , Basidiomycota/patogenicidade , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Espécies Reativas de Oxigênio/metabolismo , Triticum/crescimento & desenvolvimento , Triticum/microbiologia
5.
PLoS One ; 15(7): e0235441, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32614866

RESUMO

Although seagrasses are economically and ecologically critical species, little is known about their blade surface microbial communities and how these communities relate to the plant host. To determine microbial community composition and diversity on seagrass blade surfaces and in the surrounding seawater,16S rRNA gene sequencing (iTag) was used for samples collected at five sites along a gradient of freshwater input in the northern Gulf of Mexico on three separate sampling dates. Additionally, seagrass surveys were performed and environmental parameters were measured to characterize host characteristics and the abiotic conditions at each site. Results showed that Thalassia testudinum (turtle grass) blades hosted unique microbial communities that were distinct in composition and diversity from the water column. Environmental conditions, including water depth, salinity, and temperature, influenced community structure as blade surface microbial communities varied among sites and sampling dates in correlation with changes in environmental parameters. Microbial community composition also correlated with seagrass host characteristics, including growth rates and blade nutrient composition. There is some evidence for a core community for T. testudinum as 21 microorganisms from five phyla (Cyanobacteria, Proteobacteria, Planctomycetes, Chloroflexi, and Bacteroidetes) were present in all blade surface samples. This study provides new insights and understanding of the processes that influence the structure of marine phyllosphere communities, how these microbial communities relate to their host, and their role as a part of the seagrass holobiont, which is an important contribution given the current decline of seagrass coverage worldwide.


Assuntos
Bactérias/classificação , Água Doce/microbiologia , Hydrocharitaceae/microbiologia , Microbiota , Folhas de Planta/microbiologia , Água do Mar/microbiologia , Bactérias/genética , Golfo do México , Interações entre Hospedeiro e Microrganismos , Hydrocharitaceae/fisiologia , Filogenia , Folhas de Planta/fisiologia , RNA Ribossômico 16S/genética , Salinidade , Áreas Alagadas
6.
PLoS One ; 15(6): e0233911, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32479550

RESUMO

Promoters are very important for transcriptional regulation and gene expression, and have become invaluable tools for genetic engineering. Owing to the characteristics of obligate biotrophs, molecular research into obligate biotrophic fungi is seriously lagging behind, and very few of their endogenous promoters have been developed. In this study, a WY7 fragment was predicted in the genome of Oidium heveae Steinmann using PromoterScan. Its promoter function was verified with transient transformations (Agrobacterium tumefaciens-mediated transformation, ATMT) in Nicotiana tabacum cv. Xanthi nc. The analysis of the transcription range showed that WY7 could regulate GUS expression in both monocots (Zea mays Linn and Oryza sativa L. spp. Japonica cv. Nipponbare) and dicots (N. tabacum and Hylocereus undulates Britt). The results of the quantitative detection showed that the GUS transient expression levels when regulated by WY7 was more than 11.7 times that of the CaMV 35S promoter in dicots (N. tabacum) and 5.13 times that of the ACT1 promoter in monocots (O. sativa). GUS staining was not detected in the T1 generation of the WY7-GUS transgenic N. tabacum. This showed that WY7 is an inducible promoter. The cis elements of WY7 were predicted using PlantCARE, and further experiments indicated that WY7 was a low temperature- and salt-inducible promoter. Soluble proteins produced by WY7-hpa1Xoo transgenic tobacco elicited hypersensitive responses (HR) in N. tabacum leaves. N. tabacum transformed with pBI121-WY7-hpa1Xoo exhibited enhanced resistance to the tobacco mosaic virus (TMV). The WY7 promoter has a lot of potential as a tool for plant genetic engineering. Further in-depth studies will help to better understand the transcriptional regulation mechanisms of O. heveae.


Assuntos
Fungos/genética , Regulação Fúngica da Expressão Gênica , Engenharia Genética/métodos , Doenças das Plantas/prevenção & controle , Regiões Promotoras Genéticas , Fungos/patogenicidade , Genoma Fúngico , Hevea/genética , Hevea/microbiologia , Interações Hospedeiro-Patógeno/genética , Magnoliopsida/genética , Magnoliopsida/microbiologia , Oryza/genética , Oryza/microbiologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Plantas Geneticamente Modificadas , Tabaco/genética , Tabaco/microbiologia , Transformação Genética , Zea mays/genética , Zea mays/microbiologia
7.
PLoS One ; 15(5): e0232626, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32374762

RESUMO

The aim of this study is to determine the involvement of the flavonol-anthocyanin pathway on plant adaptation to biotic stress using the B.amyloliquefaciens QV15 to trigger blackberry metabolism and identify target genes to improve plant fitness and fruit quality. To achieve this goal, field-grown blackberries were root-inoculated with QV15 along its growth cycle. At fruiting, a transcriptomic analysis by RNA-Seq was performed on leaves and fruits of treated and non-treated field-grown blackberries after a sustained mildew outbreak; expression of the regulating and core genes of the Flavonol-Anthocyanin pathway were analysed by qPCR and metabolomic profiles by UHPLC/ESI-qTOF-MS; plant protection was found to be up to 88%. Overexpression of step-controlling genes in leaves and fruits, associated to lower concentration of flavonols and anthocyanins in QV15-treated plants, together with a higher protection suggest a phytoanticipin role for flavonols in blackberry; kempferol-3-O-rutinoside concentration was strikingly high. Overexpression of RuF3H (Flavonol-3-hidroxylase) suggests a pivotal role in the coordination of committing steps in this pathway, controlling carbon flux towards the different sinks. Furthermore, this C demand is supported by an activation of the photosynthetic machinery, and boosted by a coordinated control of ROS into a sub-lethal range, and associated to enhanced protection to biotic stress.


Assuntos
Adaptação Fisiológica , Antocianinas/metabolismo , Bacillus amyloliquefaciens/fisiologia , Sistema Enzimático do Citocromo P-450/fisiologia , Rubus/enzimologia , Rubus/microbiologia , Estresse Fisiológico , Sistema Enzimático do Citocromo P-450/genética , Frutas/enzimologia , Frutas/genética , Frutas/microbiologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas/genética , Folhas de Planta/enzimologia , Folhas de Planta/microbiologia , Rubus/genética
8.
PLoS One ; 15(5): e0233916, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32470037

RESUMO

The olive tree (Olea europaea L.) is the most important oil-producing crop of the Mediterranean basin. However, although plant protection measures are regularly applied, disease outbreaks represent an obstacle towards the further development of the sector. Therefore, there is an urge for the improvement of plant protection strategies based on information acquired by the implementation of advanced methodologies. Recently, heavy fungal infections of olive fruits have been recorded in major olive-producing areas of Greece causing devastating yield losses. Thus, initially, we have undertaken the task to identify their causal agent(s) and assess their pathogenicity and sensitivity to fungicides. The disease was identified as the olive anthracnose, and although Colletotrichum gloeosporioides and Colletotrichum acutatum species complexes are the two major causes, the obtained results confirmed that in Southern Greece the latter is the main causal agent. The obtained isolates were grouped into eight morphotypes based on their phenotypes, which differ in their sensitivities to fungicides and pathogenicity. The triazoles difenoconazole and tebuconazole were more toxic than the strobilurins being tested. Furthermore, a GC/EI/MS metabolomics model was developed for the robust chemotaxonomy of the isolates and the dissection of differences between their endo-metabolomes, which could explain the obtained phenotypes. The corresponding metabolites-biomarkers for the discrimination between morphotypes were discovered, with the most important ones being the amino acids L-tyrosine, L-phenylalanine, and L-proline, the disaccharide α,α-trehalose, and the phytotoxic pathogenesis-related metabolite hydroxyphenylacetate. These metabolites play important roles in fungal metabolism, pathogenesis, and stress responses. The study adds critical information that could be further exploited to combat olive anthracnose through its monitoring and the design of improved, customized plant protection strategies. Also, results suggest the necessity for the comprehensive mapping of the C. acutatum species complex morphotypes in order to avoid issues such as the development of fungicide-resistant genotypes.


Assuntos
Colletotrichum/fisiologia , Olea/microbiologia , Doenças das Plantas/prevenção & controle , Colletotrichum/efeitos dos fármacos , Colletotrichum/crescimento & desenvolvimento , Colletotrichum/isolamento & purificação , Flores/microbiologia , Frutas/microbiologia , Fungicidas Industriais/farmacologia , Grécia , Metabolômica , Azeite de Oliva , Folhas de Planta/microbiologia , Especificidade da Espécie , Virulência/efeitos dos fármacos
9.
Int J Food Microbiol ; 326: 108646, 2020 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-32413802

RESUMO

The effects of using contaminated seed and water on the persistence and internalization of Salmonella Newport in organic spinach cultivars- Lazio, Space, Emilia and Waitiki were studied. Seeds were contaminated by either immersing in a suspension of Salmonella and then sprouted or were sprouted in Salmonella contaminated water in the dark at 25 °C. After 5 days, germinated sprouts were analyzed for S. Newport population and internalization. Germinated sprouts were potted in soil and grown in a plant incubator for 4 weeks. Leaves, stems and roots were sampled for Salmonella population by plating on CHROMagar™. Plants surface-sterilized with chlorine were analyzed for internalized pathogen. Potting soil and water runoff were sampled for Salmonella after 4 weeks of plant growth. Contaminated seeds and irrigation water had S. Newport populations of 7.64±0.43 log CFU/g and 7.12±0.04 log CFU/ml, respectively. Sprouts germinated using contaminated water or seeds had S. Newport populations of 8.09±0.04 and 8.08±0.03 log CFU/g, respectively and had a Salmonella population that was significantly higher than other spinach tissues (P<0.05). Populations of S. Newport in leaves, stem and roots of spinach plants were as follows: contaminated seed- 2.82±1.69, 1.69±0.86, and 4.41±0.62 log CFU/ml; contaminated water- 3.56±0.90, 3.04±0.31, and 4.03±0.42 log CFU/ml of macerated tissue suspension, respectively. Internalization was observed in plants developing from contaminated seeds and in sprouts germinated using contaminated water. S. Newport populations of 2.82±0.70 log CFU/g and 1.76±0.46 log CFU/ml were recovered from soil and water runoff, respectively. The results indicate that contamination of spinach during germination can result in persistence, internalization and environmental reintroduction of Salmonella.


Assuntos
Contaminação de Alimentos/análise , Folhas de Planta/microbiologia , Salmonella enterica/isolamento & purificação , Sementes/microbiologia , Spinacia oleracea/microbiologia , Contagem de Colônia Microbiana , Microbiologia de Alimentos , Germinação , Raízes de Plantas/microbiologia , Sementes/crescimento & desenvolvimento , Microbiologia do Solo , Spinacia oleracea/crescimento & desenvolvimento
10.
Int J Syst Evol Microbiol ; 70(5): 3234-3240, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375979

RESUMO

Two novel Gram-stain-positive, irregular rod-shaped actinomycetes, S-1144T and 4053, were isolated from leaves of Lamiophlomis rotata on the Qinghai-Tibet Plateau, PR China. Cells were aerobic, catalase-positive and oxidase-negative. Colonies on Reasoner's 2A agar were light yellow, circular, shiny, smooth and convex after 2 days of incubation. The isolates grew optimally at 25 °C, pH 7.5 and with 0 % (w/v) NaCl. The results of polyphasic analyses indicated that strain S-1144T belonged to the genus Nocardioides and its close phylogenetic neighbours (16S rRNA gene sequence similarity) were Nocardioides litoris DSM 103718T (98.4 %), Nocardioides rubriscoriae DSM 23986T (98.2%) and Nocardioides plantarum DSM 11054T (97.8 %). The genome of strain S-1144T showed less than 70 % digital DNA-DNA hybridization and < 95-96 % average nucleotide identity values to the above reference strains. The DNA G+C content of strain S-1144T was 73.5 mol%. MK-8(H4) was the predominant respiratory quinone (96.0 %) and llLL-2,6-diaminopimelic acid was the diagnostic diamino acid in the cell-wall peptidoglycan. The polar lipid profile of strain S-1144T consisted of diphosphatidylglycerol, phosphatidylglycerol, three unidentified phospholipids, one unidentified glycolipid and one unidentified lipid. The major cellular fatty acids were iso-C16 : 0, C17 : 1 ω8c, C17 : 0 and C18 : 1 ω9c. On the basis of obtained data, strain S-1144T represented a novel species of the genus Nocardioides, for which the name Nocardioides dongxiaopingii sp. nov. is proposed. The type strain is S-1144T (=CGMCC 4.7568T=JCM 33469T).


Assuntos
Actinobacteria/classificação , Lamiaceae/microbiologia , Filogenia , Actinobacteria/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Bacteriano/genética , Ácido Diaminopimélico/química , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Peptidoglicano/química , Fosfolipídeos/química , Pigmentação , Folhas de Planta/microbiologia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/química
11.
PLoS One ; 15(4): e0231453, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32298310

RESUMO

A laccase-producing ascomycete fungus was isolated from soil collected around the premises of a textile dye factory and identified as Nectriella pironii. Efficient laccase production was achieved via the synergistic action of 1 mM copper sulfate and ferulic acid. Extracts of rapeseed oil cake, grass hay, and leaf litter collected in a pocket urban park were used for enzyme production. The highest laccase activity (3,330 U/L) was observed in the culture grown on the leaf litter extract. This is the first report on biosynthesis of laccase by N. pironii. This is also the first study on utilization of naturally fallen park leaves as a substrate for fungal laccase production. The extracellular enzyme possessing laccase activity was purified to homogeneity by ion-exchange and gel filtration chromatographic techniques. The amino acid sequence of the protein revealed highest similarity to the laccase enzyme produced by Stachybotrys chartarum-and considerable homology to those produced by other fungal species. The purified laccase possessed a molecular mass of 50 kDa. The enzyme had an optimum pH of 2.0 or 6.0 and retained more than 50% of residual activity after 3 hours of incubation at pH 3.0-10.6 or 4.0-9.0 when 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid or 2,6-dimethoxyphenol, respectively, were used. Dithiothreitol, ß-mercaptoethanol, and sodium azide at 1 mM concentration strongly inhibited the laccase activity, while in the presence of 50 mM urea, the enzyme was found to retain 25% of its activity. The laccase was able to decolorize more than 80% of Indigo Carmine, Remazol Brilliant Blue R, Reactive Orange 16, and Acid Red 27 dyes within 1 h. The possibility of leaf litter use for the production of the laccase enzyme from N. pironii (IM 6443), exhibiting high pH stability and degradative potential, makes it a promising tool for use in different environmental and industrial operations.


Assuntos
Ascomicetos/enzimologia , Lacase/metabolismo , Parques Recreativos , Folhas de Planta/microbiologia , Ascomicetos/crescimento & desenvolvimento , Ascomicetos/metabolismo , Microbiologia do Solo
12.
Nat Commun ; 11(1): 1910, 2020 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-32313046

RESUMO

Yield losses caused by fungal pathogens represent a major threat to global food production. One of the most devastating fungal wheat pathogens is Zymoseptoria tritici. Despite the importance of this fungus, the underlying mechanisms of plant-pathogen interactions are poorly understood. Here we present a conceptual framework based on coinfection assays, comparative metabolomics, and microbiome profiling to study the interaction of Z. tritici in susceptible and resistant wheat. We demonstrate that Z. tritici suppresses the production of immune-related metabolites in a susceptible cultivar. Remarkably, this fungus-induced immune suppression spreads within the leaf and even to other leaves, a phenomenon that we term "systemic induced susceptibility". Using a comparative metabolomics approach, we identify defense-related biosynthetic pathways that are suppressed and induced in susceptible and resistant cultivars, respectively. We show that these fungus-induced changes correlate with changes in the wheat leaf microbiome. Our findings suggest that immune suppression by this hemibiotrophic pathogen impacts specialized plant metabolism, alters its associated microbial communities, and renders wheat vulnerable to further infections.


Assuntos
Ascomicetos/metabolismo , Interações Hospedeiro-Patógeno/imunologia , Interações Hospedeiro-Patógeno/fisiologia , Metaboloma , Microbiota/fisiologia , Imunidade Vegetal/fisiologia , Ascomicetos/patogenicidade , Benzoxazinas/metabolismo , Vias Biossintéticas , Coinfecção , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Metabolismo Secundário , Triticum/imunologia , Triticum/microbiologia
13.
Artigo em Inglês | MEDLINE | ID: mdl-32251954

RESUMO

The effects of two purified fractions (formerly D-SXM and ND-SXM) produced in vitro by defoliating (Vd312D) and non-defoliating (Vd315ND) strains of Verticillium dahliae were studied on twigs of Olea europaea cvs Frantoio and Leccino. Symptoms, such as leaf curling, yellowing, vein clearing and defoliation, which are observed on the two cultivars naturally affected by Verticillium wilt, were produced by these fractions. Physiological changes were induced during the first seven days after the absorption of solutions containing ND-SXM or D-SXM. Both fractions increased the transpiration flow from abaxial leaf surfaces. Cell membrane and antioxidant activity were the most important action sites of ND-SXM and D-SXM. ND-SXM influenced malondialdehyde concentration in 'Leccino' leaves, while D-SXM increased the percentage of electrolyte leakage in 'Frantoio'. Both fractions reduced the total non-enzymatic antioxidant activity on the leaves of the treated twigs. The total phenol content increased in both cultivars, without differences to the control. Variations on electrolyte leakage and total antioxidant activity were effective in discriminating the two tested olive cultivars for V. dahliae tolerance or susceptibility. If V. dahliae strains Vd315ND and Vd312D produce ND-SXM and D-SXM in the infected plants, these metabolites may move via the xylem sap, accumulate in the leaves and induce changes that will lead symptoms on the leaf by compromising the cell membranes physiology.


Assuntos
Olea , Verticillium , Olea/microbiologia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Caules de Planta/microbiologia , Verticillium/química , Xilema/metabolismo
14.
Electron. j. biotechnol ; 44: 14-18, Mar. 2020. ilus, graf
Artigo em Inglês | LILACS | ID: biblio-1087629

RESUMO

BACKGROUND: Although bioactive metabolites capable of causing oxidative photo-necrosis in plant tissues have been identified in fungi, little is known about this type of mechanism in bacteria. These metabolites act as photosensitizers that generate reactive oxygen species (ROS) capable of causing damage to cells. In addition, these metabolites can pass into an energetically excited state when they receive some luminous stimulus, a condition in which they interact with other molecules present in the environment, such as molecular oxygen (O2), also known as triplet oxygen (3 O2), generating ROS. RESULTS: The suspension of the bacterial culture of Pseudomonas cedrina was shown to produce foliar necrosis in papaya leaves (Carica papaya L.) only in the presence of sunlight, which is evidence of photosensitizing mechanisms that generate singlet oxygen (1 O2). From the chemical study of extracts obtained from this bacteria, 3-(4-(2-carboxipropyl) phenyl) but-2-enoic acid (1) was isolated. This compound, in the presence of light and triplet oxygen (3 O2), was able to oxidize ergosterol to its peroxide, since it acted as a photosensitizer producing 1 O2, with which it was corroborated that a photosensitization reaction occurs, mechanism by which this bacterium could prove to cause oxidative foliar photo-necrosis. CONCLUSIONS: P. cedrina was able to induce oxidative foliar photo-necrosis because of its potential ability to produce photosensitizing metabolites that generate singlet oxygen in the plants it colonizes. Based on the above, it can be proposed that some bacteria can cause oxidative foliar photo-necrosis as an important mechanism in the pathogenesis of host species.


Assuntos
Doenças das Plantas/microbiologia , Pseudomonas/fisiologia , Carica/microbiologia , Oxigênio Singlete/metabolismo , Pseudomonas/metabolismo , Ácidos , Espécies Reativas de Oxigênio , Folhas de Planta/microbiologia , Foto-Oxidação , Luz , Necrose
15.
World J Microbiol Biotechnol ; 36(3): 47, 2020 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-32144505

RESUMO

Beauveria bassiana (Bals.) Vuillemin (B. bassiana) is an entomopathogenic fungus that establishes endophytic symbiosis with plants. In the present study, the effects of B. bassiana strains colonization in growing Zea mays L. (Z. mays), crop production, and drought tolerance were evaluated. Z. mays seeds were inoculated with B. bassiana strains (GHA, PTG4, and PTG6), using 1 × 106 blastospores/mL and methyl cellulose (MC) or cornstarch (CS) as adherents. Colonization was determined by B. bassiana recovery from plant tissues plated on PDA medium. Plant height, fresh and dry weight, and flowering time were analyzed to assess plant performance. Drought tolerance was evaluated by stopping watering for 10 days, watering again, and determining vigor recovery after 24 h. Results showed 100% endophytic roots colonization, regardless of adherent type or strain tested. Colonization was variable in shoots and leaves, but GHA strain achieved the highest inoculation rates, including 88% in stems and 50% in leaves, which did not depend on adherent type used; for PTG4 strain, adherent type had an important effect (MC = 100% stems and leaves; CS = 63% stems and 25% leaves). For PTG6 strain, the best adherent type was CS (71% stems and 75% leaves), whereas MC showed variable inoculation percentage (25% stems and 75% leaves). Interestingly, only MCPTG4 treatment showed consistent positive effects on germination percentage (day 5 = 46 ± 2%; day 14 = 87 ± 7%) compared with controls (CC = 63 ± 4%, CMC = 50 ± 3%, CCS = 47 ± 0%). In addition, the other treatments showed low germination percentages at day 5 (7 ± 7% to 46 ± 2%), which recovered at day 14 (53 ± 0% to 73 ± 8%), except for MCPTG6 treatment with 23 ± 10% germination. About plant performance, not significant effects on plant height and fresh/dry weight in all the treatments were observed. However, B. bassiana-treated plants, using either GHA, PTG4 or PTG6 strains, and MC as adherent, showed tolerance to drought and flowered one to two weeks earlier, providing evidence supporting further applications of these seed treatments in agricultural systems, for abiotic stress sustainable management practices.


Assuntos
Beauveria/fisiologia , Secas , Endófitos/fisiologia , Flores/crescimento & desenvolvimento , Estresse Fisiológico , Zea mays/crescimento & desenvolvimento , Germinação , Desenvolvimento Vegetal , Folhas de Planta/microbiologia , Sementes/crescimento & desenvolvimento , Sementes/microbiologia , Simbiose , Zea mays/microbiologia
16.
PLoS One ; 15(3): e0230286, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32142558

RESUMO

Circular leaf spot, caused by the ascomycetous fungus Plurivorosphaerella nawae (= Mycosphaerella nawae), is the most problematic fungal disease of persimmon worldwide. In Korea, persimmon exposed to P. nawae inoculum (ascospores) from May to August shows visible circular leaf spot disease symptoms from the end of August to early September. It is important to identify factors affecting this long latent period. The objective of this study was to elucidate the relation between the development of symptom of circular leaf spot and the content of phenolics compounds and vitamin C as well as the antioxidant activities in leaves. Healthy leaves (both young and old) and infected leaves of circular leaf spot-susceptible persimmon cultivar were harvested in 2016. The content of phenolics (total phenols, flavonoids, and tannins) and vitamin C, and their antioxidant activities were analyzed in all types of leaves. Compared with the asymptomatic leaves (old) and the asymptomatic parts of the infected leaves, the symptomatic parts of the infected leaves, symptomatic leaves, and asymptomatic young leaves showed significantly higher content of phenolics and vitamin C, and higher antioxidant activities. Disease incidence and severity were estimated for older leaves (emerged in early May) and younger leaves (emerged at the end of June) in 2017 and 2018. The AUDPC was higher in old leaves than younger leaves. The disease progression was much faster and severe in the older than in the younger leaves. Similar results were found in field experiments. Higher content of phenolics and antioxidant activities in the younger leaves may contribute to circular leaf spot resistance in persimmon. Furthermore, accumulation of phenolics and antioxidant activity in the infected leaves is a post-infection response and the first stage of the defense mechanism.


Assuntos
Diospyros/metabolismo , Imunidade Vegetal , Folhas de Planta/metabolismo , Ascomicetos/patogenicidade , Ácido Ascórbico/metabolismo , Diospyros/imunologia , Diospyros/microbiologia , Flavonoides/metabolismo , Folhas de Planta/microbiologia , Taninos/metabolismo
17.
Aquat Toxicol ; 222: 105461, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32171118

RESUMO

Antibiotics may constitute a risk for aquatic detritivorous macroinvertebrates (i.e., shredders) via waterborne and dietary antibiotic exposure. In addition, antibiotics can alter the food quality for shredders mediated by shifts in leaf-associated decomposer (i.e., aquatic fungi and bacteria) communities. However, little is known about the relative importance of the waterborne and dietary effect pathway. Therefore, we followed a tiered testing approach aimed at assessing the relative importance of these effect pathways. We employed the antibiotic ciprofloxacin (CIP) and the shredder Gammarus fossarum as model stressor and test species, respectively. In a first step, we assessed the short-term waterborne toxicity of CIP using survival and leaf consumption of G. fossarum as response variables. Alterations in the leaf-associated decomposer community, which may be reflected by their palatability, were assessed using food choice assays. Finally, we conducted a 2 × 2-factorial experiment over 24 days assessing the pathways individually and combined using energy processing (i.e., leaf consumption and feces production), growth and energy storage (i.e., neutral lipid fatty acids) as variables. Short term waterborne exposure indicated low toxicity with LC50 and EC50 values of 13.6 and 6.4 mg CIP/L, respectively. At the same time, shredders did not prefer any leaf material during the food choice assay. However, the fungal community was significantly affected in the highest CIP-treatments (0.5 and 2.5 mg/L) suggesting an altered food quality for shredders. This assumption is supported by the results of the long-term assay. At 0.5 mg CIP/L, gammarids' leaf consumption, growth and energy storage were increased when subjected via the dietary pathway, which was linked to changes in the leaf-associated microbial community. Our data highlight the importance of dietary effect pathways for effects on shredders, potentially impacting energy dynamics in detritus-based stream ecosystems.


Assuntos
Anfípodes/efeitos dos fármacos , Antibacterianos/toxicidade , Ciprofloxacino/toxicidade , Comportamento Alimentar/efeitos dos fármacos , Folhas de Planta/metabolismo , Poluentes Químicos da Água/toxicidade , Anfípodes/metabolismo , Animais , Antibacterianos/análise , Ciprofloxacino/análise , Dieta , Ecossistema , Microbiota/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Folhas de Planta/microbiologia , Rios/química
18.
Int J Syst Evol Microbiol ; 70(4): 2640-2647, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32202992

RESUMO

A Gram-stain-negative, aerobic, rod-shaped, leaf-associated bacterium, designated JS23T, was isolated from surface-sterilized leaf tissue of an oil palm grown in Singapore and was investigated by polyphasic taxonomy. Phylogenetic analyses based on 16S rRNA gene sequences and 180 conserved genes in the genome of several members of Burkholderiaceae revealed that strain JS23T formed a distinct evolutionary lineage independent of other taxa within the family Burkholderiaceae. The predominant ubiquinone was Q-8. The primary polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, and an unidentified aminophospholipid. The major fatty acids were C16 : 0, summed feature 3 (C16 : 1 ω7c /C16 : 1 ω6c) and summed feature 8 (C18 : 1 ω7c /C18 : 1 ω6c). The size of the genome is 5.36 Mbp with a DNA G+C content of 66.2 mol%. Genomic relatedness measurements such as average nucleotide identity, genome-to-genome distance and digital DNA-DNA hybridization clearly distinguished strain JS23T from the closely related genera Burkholderia, Caballeronia, Mycetohabitans, Mycoavidus, Pandoraea, Paraburkholderia, Robbsia and Trinickia. Furthermore, average amino acid identity values and the percentages of conserved proteins, 56.0-68.4 and 28.2-45.5, respectively, were well below threshold values for genus delineation and supported the assignment of JS23T to a novel genus. On the basis of the phylogenetic, biochemical, chemotaxonomic and phylogenomic evidence, strain JS23T is proposed to represent a novel species of a new genus within the family Burkholderiaceae, for which the name Chitinasiproducens palmae gen. nov., sp. nov., is proposed with the type strain of JS23T (= DSM 27307T=KACC 17592T).


Assuntos
Arecaceae/microbiologia , Burkholderiaceae/classificação , Filogenia , Folhas de Planta/microbiologia , Técnicas de Tipagem Bacteriana , Composição de Bases , Burkholderiaceae/isolamento & purificação , DNA Bacteriano/genética , Ácidos Graxos/química , Hibridização de Ácido Nucleico , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Singapura , Ubiquinona/química
19.
Pol J Microbiol ; 69(1): 91-97, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32189484

RESUMO

The root of Paris polyphylla var. yunnanensis, a famous and endangered traditional Chinese herb, has a significant medicinal value. The aim of this study was to analyze the composition and functional characteristics of bacterial endophytes in roots, stems, and leaves of P. polyphylla var. yunnanensis. The 16S rRNA gene sequencing and functional prediction of bacterial endophytes in roots, stems, and leaves of P. polyphylla var. yunnanensis were conducted. The Chao and Shannon indices of the bacteria in roots were significantly higher than those in stems and leaves. The dominant endophyte phyla were Cyanobacteria, Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. The main genera detected in roots were unclassified Cyanobacteria, Rhizobium, Flavobacterium, and Sphingobium; the main genera in stems were norank_c__Cyanobacteria, Bacillus, and Pseudomonas; the main genera in leaves were norank_c__Cyanobacteria and Rhizobium. The microbiota in roots was particularly enriched in functional categories "extracellular structures" and "cytoskeleton" compared with stems and leaves (p < 0.05). Our study reveals the structural and functional characteristics of the endophytic bacteria in roots, stems, and leaves of P. polyphylla var. yunnanensis, which aids in the scientific understanding of this plant.The root of Paris polyphylla var. yunnanensis, a famous and endangered traditional Chinese herb, has a significant medicinal value. The aim of this study was to analyze the composition and functional characteristics of bacterial endophytes in roots, stems, and leaves of P. polyphylla var. yunnanensis. The 16S rRNA gene sequencing and functional prediction of bacterial endophytes in roots, stems, and leaves of P. polyphylla var. yunnanensis were conducted. The Chao and Shannon indices of the bacteria in roots were significantly higher than those in stems and leaves. The dominant endophyte phyla were Cyanobacteria, Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. The main genera detected in roots were unclassified Cyanobacteria, Rhizobium, Flavobacterium, and Sphingobium; the main genera in stems were norank_c__Cyanobacteria, Bacillus, and Pseudomonas; the main genera in leaves were norank_c__Cyanobacteria and Rhizobium. The microbiota in roots was particularly enriched in functional categories "extracellular structures" and "cytoskeleton" compared with stems and leaves (p < 0.05). Our study reveals the structural and functional characteristics of the endophytic bacteria in roots, stems, and leaves of P. polyphylla var. yunnanensis, which aids in the scientific understanding of this plant.


Assuntos
Bactérias/classificação , Liliaceae/microbiologia , Folhas de Planta/microbiologia , Raízes de Plantas/microbiologia , Caules de Planta/microbiologia , Plantas Medicinais/microbiologia , Endófitos/classificação , Medicina Tradicional Chinesa
20.
Artigo em Inglês | MEDLINE | ID: mdl-32067565

RESUMO

Bioremediation is one of the existing techniques applied for treating oil-contaminated soil, which can be improved by the incorporation of low-cost nutritional materials. This study aimed to assess the addition of two low-cost plant residues, sugarcane bagasse (SCB) and leaf litter (LL) of the forest leguminous Mimosa caesalpiniifolia plant (sabiá), either separately or combined, to a contaminated soil from a petroleum refinery area, analyzed after 90 days of treatment. Individually, both amounts of SCB (20 and 40 g kg-1) favored the growth of total heterotrophic bacteria and total fungi, while LL at 20 g kg-1 better stimulated the hydrocarbon-degrading microorganism's activity in the soil. However, no TPH removal was observed under any of these conditions. Higher microbial growth was detected by the application of both plant residues in multicontaminated soil. The maximum TPH removal of 30% was achieved in amended soil with 20 g kg-1 SCB and 20 kg-1 LL. All the experimental conditions revealed changes in the microbial community structure, related to the handling of the soil, with abundance of Alphaproteobacteria. This study demonstrates the effectiveness of the plant residues SCB and LL as low-cost nutritional materials for biodegradation of hydrocarbon in real oil contaminated soil by indigenous populations.


Assuntos
Microbiota , Indústria de Petróleo e Gás , Petróleo/análise , Microbiologia do Solo , Poluentes do Solo/análise , Solo/química , Alphaproteobacteria/crescimento & desenvolvimento , Biodegradação Ambiental , Brasil , Celulose/química , Mimosa/química , Mimosa/microbiologia , Petróleo/metabolismo , Folhas de Planta/química , Folhas de Planta/microbiologia , Saccharum/química , Saccharum/microbiologia , Poluentes do Solo/metabolismo , Resíduos Sólidos
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