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Abstract Background Cardiovascular complications of COVID-19 are important aspects of the disease’s pathogenesis and prognosis. Evidence on the prognostic role of troponin and myocardial injury in Latin American hospitalized COVID-19 patients is still scarce. Objectives To evaluate myocardial injury as independent predictor of in-hospital mortality and invasive mechanical ventilation support in hospitalized patients, from the Brazilian COVID-19 Registry. Methods This cohort study is a substudy of the Brazilian COVID-19 Registry, conducted in 31 Brazilian hospitals of 17 cities, March-September 2020. Primary outcomes included in-hospital mortality and invasive mechanical ventilation support. Models for the primary outcomes were estimated by Poisson regression with robust variance, with statistical significance of p<0.05. Results Of 2,925 patients (median age of 60 years [48-71], 57.1% men), 27.3% presented myocardial injury. The proportion of patients with comorbidities was higher among patients with cardiac injury (median 2 [1-2] vs. 1 [0-2]). Patients with myocardial injury had higher median levels of brain natriuretic peptide, lactate dehydrogenase, creatine phosphokinase, N-terminal pro-brain natriuretic peptide, and C-reactive protein than patients without myocardial injury. As independent predictors, C-reactive protein and platelet counts were related to the risk of death, and neutrophils and platelet counts were related to the risk of invasive mechanical ventilation support. Patients with high troponin levels presented a higher risk of death (RR 2.03, 95% CI 1.60-2.58) and invasive mechanical ventilation support (RR 1.87, 95% CI 1.57-2.23), when compared to those with normal troponin levels. Conclusion Cardiac injury was an independent predictor of in-hospital mortality and the need for invasive mechanical ventilation support in hospitalized COVID-19 patients.

Resumo Fundamento As complicações cardiovasculares da COVID-19 são aspectos importantes da patogênese e do prognóstico da doença. Evidências do papel prognóstico da troponina e da lesão miocárdica em pacientes hospitalizados com COVID-19 na América Latina são ainda escassos. Objetivos Avaliar a lesão miocárdica como preditor independente de mortalidade hospitalar e suporte ventilatório mecânico em pacientes hospitalizados, do registro brasileiro de COVID-19. Métodos Este estudo coorte é um subestudo do registro brasileiro de COVID-19, conduzido em 31 hospitais brasileiros de 17 cidades, de março a setembro de 2020. Os desfechos primários incluíram mortalidade hospitalar e suporte ventilatório mecânico invasivo. Os modelos para os desfechos primários foram estimados por regressão de Poisson com variância robusta, com significância estatística de p<0,05. Resultados Dos 2925 pacientes [idade mediana de 60 anos (48-71), 57,1%], 27,3% apresentaram lesão miocárdica. A proporção de pacientes com comorbidades foi maior nos pacientes com lesão miocárdica [mediana 2 (1-2) vs. 1 (0-20)]. Os pacientes com lesão miocárdica apresentaram maiores valores medianos de peptídeo natriurético cerebral, lactato desidrogenase, creatina fosfoquinase, N-terminal do pró-peptídeo natriurético tipo B e proteína C reativa em comparação a pacientes sem lesão miocárdica. Como fatores independentes, proteína C reativa e contagem de plaquetas foram relacionados com o risco de morte, e neutrófilos e contagem de plaquetas foram relacionados ao risco de suporte ventilatório mecânico invasivo. Os pacientes com níveis elevados de troponina apresentaram um maior risco de morte (RR 2,03, IC95% 1,60-2,58) e suporte ventilatório mecânico (RR 1,87;IC95% 1,57-2,23), em comparação àqueles com níveis de troponina normais. Conclusão Lesão cardíaca foi um preditor independente de mortalidade hospitalar e necessidade de suporte ventilatório mecânico em pacientes hospitalizados com COVID-19.

https://doi.org/10.36660/abc.20220151

Effects on gene expression during maize-Azospirillum interaction in the presence of a plant-specific inhibitor of indole-3-acetic acid production
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Espindula, Eliandro

; Sperb, Edilena Reis

; Moz, Brenda

; Pankievicz, Vânia Carla Silva

; Tuleski, Thalita Regina

; Tadra-Sfeir, Michelle Zibetti

; Bonato, Paloma

; Scheid, Camila

; Merib, Josias

; Souza, Emanuel Maltempi de

; Passaglia, Luciane Maria Pereira

Genetics and Molecular Biology

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2023, Volume 46 Nº 3 elocation e20230100

Resumo: En | Texto: En | PDF: En

Abstract Amongst the sustainable alternatives to increase maize production is the use of plant growth-promoting bacteria (PGPB). Azospirillum brasilense is one of the most well-known PGPB being able to fix nitrogen and produce phytohormones, especially indole-3-acetic acid - IAA. This work investigated if there is any contribution of the bacterium to the plant’s IAA levels, and how it affects the plant. To inhibit plant IAA production, yucasin, an inhibitor of the TAM/YUC pathway, was applied. Plantlets’ IAA concentration was evaluated through HPLC and dual RNA-Seq was used to analyze gene expression. Statistical differences between the group treated with yucasin and the other groups showed that A. brasilense inoculation was able to prevent the phenotype caused by yucasin concerning the number of lateral roots. Genes involved in the auxin and ABA response pathways, auxin efflux transport, and the cell cycle were regulated by the presence of the bacterium, yucasin, or both. Genes involved in the response to biotic/abiotic stress, plant disease resistance, and a D-type cellulose synthase changed their expression pattern among two sets of comparisons in which A. brasilense acted as treatment. The results suggest that A. brasilense interferes with the expression of many maize genes through an IAA-independent pathway.

https://doi.org/10.1590/1678-4685-gmb-2023-0100

Genome-based analyses to learn from and about Paenibacillus sonchi genomovar Riograndensis SBR5T
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Wendisch, Volker F.

; Brito, Luciana F.

; Passaglia, Luciane M.P.

Genetics and Molecular Biology

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2023, Volume 46 Nº 3 elocation e20230115

Resumo: En | Texto: En | PDF: En

Abstract Paenibacillus sonchi genomovar Riograndensis SBR5T is a plant growth-promoting rhizobacterium (PGPR) isolated in the Brazilian state of Rio Grande do Sul from the rhizosphere of Triticum aestivum. It fixes nitrogen, produces siderophores as well as the phytohormone indole-3-acetic acid, solubilizes phosphate and displays antagonist activity against Listeria monocytogenes and Pectobacterium carotovorum. Comprehensive omics analysis and the development of genetic tools are key to characterizing and engineering such non-model microorganisms. Therefore, the complete genome of SBR5T was sequenced, and shown to encode 6,705 proteins, 87 tRNAs, and 27 rRNAs and it enabled a landscape transcriptome analysis that unveiled conserved transcriptional and translational patterns and characterized operon structures and riboswitches. The pangenome of P. sonchi species is open with a stable core pangenome. At the same time, the analysis of genes coding for nitrogenases revealed that the trait of nitrogen fixation is sparse within the Paenibacillaceae family and the presence of Fe-only nitrogenase in the P. sonchi group was exclusive to SBR5T. The development of genetic tools for SBR5T enabled genetic transformation, plasmid construction for constitutive and inducible gene expression, and gene repression using the CRISPRi system. Altogether, the work with P. sonchi can guide the study of non-model bacteria with economic potential.

https://doi.org/10.1590/1678-4685-gmb-2023-0115

Genome-based taxonomy of Burkholderia sensu lato: Distinguishing closely related species
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Bach, Evelise

; Volpiano, Camila Gazolla

; Sant’Anna, Fernando Hayashi

; Passaglia, Luciane Maria Pereira

Genetics and Molecular Biology

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2023, Volume 46 Nº 3 elocation e20230122

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Abstract The taxonomy of Burkholderia sensu lato (s.l.) has been revisited using genome-based tools, which have helped differentiate closely related species. Many species from this group are indistinguishable through phenotypic traits and 16S rRNA gene sequence analysis. Furthermore, they also exhibit whole-genome Average Nucleotide Identity (ANI) values in the twilight zone for species circumscription (95-96%), which may impair their correct classification. In this work, we provided an updated Burkholderia s.l. taxonomy focusing on closely related species and give other recommendations for those developing genome-based taxonomy studies. We showed that a combination of ANI and digital DNA-DNA hybridization (dDDH) applying the universal cutoff values of 95% and 70%, respectively, successfully discriminates Burkholderia s.l. species. Using genome metrics with this pragmatic criterion, we demonstrated that i) Paraburkholderia insulsa should be considered a later heterotypic synonym of Paraburkholderia fungorum; ii) Paraburkholderia steynii differs from P. terrae by harboring symbiotic genes; iii) some Paraburkholderia are indeed different species based on dDDH values, albeit sharing ANI values close to 95%; iv) some Burkholderia s.l. indeed represent new species from the genomic viewpoint; iv) some genome sequences should be evaluated with care due to quality concerns.

https://doi.org/10.1590/1678-4685-gmb-2023-0122

The combined analysis as the best strategy for Dual RNA-Seq mapping
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Espindula, Eliandro

; Sperb, Edilena Reis

; Bach, Evelise

; Passaglia, Luciane Maria Pereira

Genetics and Molecular Biology

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2019, Volume 42 Nº 4 elocation e20190215

Resumo: En | Texto: En | PDF: En

Abstract In Dual RNA-Seq experiments the simultaneous extraction of RNA and analysis of gene expression data from both interacting organisms could be a challenge. One alternative is separating the reads during in silico data analysis. There are two main mapping methods used: sequential and combined. Here we present a combined approach in which the libraries were aligned to a concatenated genome to sort the reads before mapping them to the respective annotated genomes. A comparison of this method with the sequential analysis was performed. Two RNA-Seq libraries available in public databases consisting of a eukaryotic (Zea mays) and a prokaryotic (Herbaspirillum seropediceae) organisms were mixed to simulate a Dual RNA-Seq experiment. Libraries from real Dual RNA-Seq experiments were also used. The sequential analysis consistently attributed more reads to the first reference genome used in the analysis (due to cross-mapping) than the combined approach. More importantly, the combined analysis resulted in lower numbers of cross-mapped reads. Our results highlight the necessity of combining the reference genomes to sort reads previously to the counting step to avoid losing information in Dual RNA-Seq experiments. Since most studies first map the RNA-Seq libraries to the eukaryotic genome, much prokaryotic information has probably been lost.

https://doi.org/10.1590/1678-4685-gmb-2019-0215 1538 downloads

The genomes of three Bradyrhizobium sp. isolated from root nodules of Lupinus albescens grown in extremely poor soils display important genes for resistance to environmental stress
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Granada, Camille E.

; Vargas, Luciano K.

; Sant’Anna, Fernando Hayashi

; Balsanelli, Eduardo

; Baura, Valter Antonio de

; Oliveira Pedrosa, Fábio de

; Souza, Emanuel Maltempi de

; Falcon, Tiago

; Passaglia, Luciane M.P.

Genetics and Molecular Biology

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Jun 2018, Volume 41 Nº 2 Páginas 502 - 506

Resumo: En | Texto: En | PDF: En

Abstract Lupinus albescens is a resistant cover plant that establishes symbiotic relationships with bacteria belonging to the Bradyrhizobium genus. This symbiosis helps the development of these plants in adverse environmental conditions, such as the ones found in arenized areas of Southern Brazil. This work studied three Bradyrhizobium sp. (AS23, NAS80 and NAS96) isolated from L. albescens plants that grow in extremely poor soils (arenized areas and adjacent grasslands). The genomes of these three strains were sequenced in the Ion Torrent platform using the IonXpress library preparation kit, and presented a total number of bases of 1,230,460,823 for AS23, 1,320,104,022 for NAS80, and 1,236,105,093 for NAS96. The genome comparison with closest strains Bradyrhizobium japonicum USDA6 and Bradyrhizobium diazoefficiens USDA110 showed important variable regions (with less than 80% of similarity). Genes encoding for factors for resistance/tolerance to heavy metal, flagellar motility, response to osmotic and oxidative stresses, heat shock proteins (present only in the three sequenced genomes) could be responsible for the ability of these microorganisms to survive in inhospitable environments. Knowledge about these genomes will provide a foundation for future development of an inoculant bioproduct that should optimize the recovery of degraded soils using cover crops.

https://doi.org/10.1590/1678-4685-gmb-2017-0098 1342 downloads

Bradyrhizobium elkanii nod regulon: insights through genomic analysis
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Passaglia, Luciane M. P.

Genetics and Molecular Biology

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Set 2017, Volume 40 Nº 3 Páginas 703 - 716

Resumo: En | Texto: En | PDF: En

Abstract A successful symbiotic relationship between soybean [Glycine max (L.) Merr.] and Bradyrhizobium species requires expression of the bacterial structural nod genes that encode for the synthesis of lipochitooligosaccharide nodulation signal molecules, known as Nod factors (NFs). Bradyrhizobium diazoefficiens USDA 110 possesses a wide nodulation gene repertoire that allows NF assembly and modification, with transcription of the nodYABCSUIJnolMNOnodZ operon depending upon specific activators, i.e., products of regulatory nod genes that are responsive to signaling molecules such as flavonoid compounds exuded by host plant roots. Central to this regulatory circuit of nod gene expression are NodD proteins, members of the LysR-type regulator family. In this study, publicly available Bradyrhizobium elkanii sequenced genomes were compared with the closely related B. diazoefficiens USDA 110 reference genome to determine the similarities between those genomes, especially with regards to the nod operon and nod regulon. Bioinformatics analyses revealed a correlation between functional mechanisms and key elements that play an essential role in the regulation of nod gene expression. These analyses also revealed new genomic features that had not been clearly explored before, some of which were unique for some B. elkanii genomes.

https://doi.org/10.1590/1678-4685-gmb-2016-0228 1116 downloads

Functional abilities of cultivable plant growth promoting bacteria associated with wheat (Triticum aestivum L.) crops
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Moreira, Fernanda da S.

; Costa, Pedro B. da

; Souza, Rocheli de

; Beneduzi, Anelise

; Lisboa, Bruno B.

; Vargas, Luciano K.

; Passaglia, Luciane M. P.

Genetics and Molecular Biology

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Mar 2016, Volume 39 Nº 1 Páginas 111 - 121

Resumo: En | Texto: En | PDF: En

Abstract In the pursuit of sustainable agriculture, bioinoculants usage as providers of a crop's needs is a method to limit environmental damage. In this study, a collection of cultivable putative plant growth promoting (PGP) bacteria associated with wheat crops was obtained and this bacterial sample was characterized in relation to the functional diversity of certain PGP features. The isolates were obtained through classical cultivation methods, identified by partial 16S rRNA gene sequencing and characterized for PGP traits of interest. Functional diversity characterization was performed using Categorical Principal Component Analysis (CatPCA) and Multiple Correspondence Analysis (MCA). The most abundant genera found among the 346 isolates were Pseudomonas, Burkholderia, and Enterobacter. Occurrence of PGP traits was affected by genus, niche, and sampling site. A large number of genera grouped together with the ability to produce indolic compounds; phosphate solubilization and siderophores production formed a second group related to fewer genera, in which the genus Burkholderia has a great importance. The results obtained may help future studies aiming prospection of putative plant growth promoting bacteria regarding the desired organism and PGP trait.

https://doi.org/10.1590/1678-4685-GMB-2015-0140 2420 downloads

Plant growth-promoting bacteria as inoculants in agricultural soils
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Souza, Rocheli de

; Ambrosini, Adriana

; Passaglia, Luciane M.P.

Genetics and Molecular Biology

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Dez 2015, Volume 38 Nº 4 Páginas 401 - 419

Resumo: En | Texto: En | PDF: En

Abstract Plant-microbe interactions in the rhizosphere are the determinants of plant health, productivity and soil fertility. Plant growth-promoting bacteria (PGPB) are bacteria that can enhance plant growth and protect plants from disease and abiotic stresses through a wide variety of mechanisms; those that establish close associations with plants, such as the endophytes, could be more successful in plant growth promotion. Several important bacterial characteristics, such as biological nitrogen fixation, phosphate solubilization, ACC deaminase activity, and production of siderophores and phytohormones, can be assessed as plant growth promotion (PGP) traits. Bacterial inoculants can contribute to increase agronomic efficiency by reducing production costs and environmental pollution, once the use of chemical fertilizers can be reduced or eliminated if the inoculants are efficient. For bacterial inoculants to obtain success in improving plant growth and productivity, several processes involved can influence the efficiency of inoculation, as for example the exudation by plant roots, the bacterial colonization in the roots, and soil health. This review presents an overview of the importance of soil-plant-microbe interactions to the development of efficient inoculants, once PGPB are extensively studied microorganisms, representing a very diverse group of easily accessible beneficial bacteria.

https://doi.org/10.1590/S1415-475738420150053 24420 downloads

10.

Microbial quality of soil from the Pampa biome in response to different grazing pressures
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Vargas, Rafael S.

; Bataiolli, Renata

; da Costa, Pedro B.

; Lisboa, Bruno

; Passaglia, Luciane Maria P.

; Beneduzi, Anelise

; Vargas, Luciano K.

Genetics and Molecular Biology

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Jun 2015, Volume 38 Nº 2 Páginas 205 - 212

Resumo: En | Texto: En | PDF: En

The aim of this study was to evaluate the impact of different grazing pressures on the activity and diversity of soil bacteria. We performed a long-term experiment in Eldorado do Sul, southern Brazil, that assessed three levels of grazing pressure: high pressure (HP), with 4% herbage allowance (HA), moderate pressure (MP), with 12% HA, and low pressure (LP), with 16% HA. Two reference areas were also assessed, one of never-grazed native vegetation (NG) and another of regenerated vegetation after two years of grazing (RG). Soil samples were evaluated for microbial biomass and enzymatic (β-glucosidase, arylsulfatase and urease) activities. The structure of the bacterial community and the population of diazotrophic bacteria were evaluated by RFLP of the 16S rRNA and nifH genes, respectively. The diversity of diazotrophic bacteria was assessed by partial sequencing of the 16S rDNA gene. The presence of grazing animals increased soil microbial biomass in MP and HP. The structures of the bacterial community and the populations of diazotrophic bacteria were altered by the different grazing managements, with a greater diversity of diazotrophic bacteria in the LP treatment. Based on the characteristics evaluated, the MP treatment was the most appropriate for animal production and conservation of the Pampa biome.

https://doi.org/10.1590/S1415-475738138120140230 1886 downloads

11.

Screening of plant growth promoting bacteria associated with barley plants (Hordeum vulgare L.) cultivated in South Brazil
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Pontes, Andress P.

; Souza, Rocheli de

; Granada, Camille E.

; Passaglia, Luciane M.P.

Biota Neotropica

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Jun 2015, Volume 15 Nº 2 elocation e20140105

Resumo: Pt En | Texto: Pt En | PDF: Pt | PDF: En

A ocorrência de associações entre bactérias e raízes de plantas pode ser benéfica, neutra ou prejudicial. Bactérias promotoras de crescimento vegetal (BPCV) formam um grupo heterogêneo de micro-organismos benéficos que pode ser encontrado na rizosfera, superfícies de raízes ou em associação com plantas hospedeiras. O objetivo deste estudo foi isolar e caracterizar bactérias promotoras do crescimento vegetal (PCV) associadas a plantas de cevada (Hordeum vulgare L.), visando uma futura aplicação como inoculante agrícola. Cento e sessenta linhagens bacterianas foram isoladas a partir de raízes ou solo rizosférico de cevada com base na sua multiplicação em meios seletivos sem nitrogênio. Todos os isolados foram avaliados quanto è sua capacidade de produzir compostos indólicos (CIs), sideróforos e solubilizar fosfato tricálcio, em ensaios in vitro. A maioria dos isolados (74%) foi capaz de sintetizar CIs na presença do precursor L-triptofano, enquanto que 57% produziram sideróforos em meio líquido com deficiência de Fe e 17% foram capazes de solubilizar fosfato tricálcio. Trinta e dois isolados que apresentaram diferentes características PCV foram identificados pelo sequenciamento parcial do gene 16S rRNA. Linhagens pertencentes aos gêneros Cedecea eMicrobacterium promoveram o crescimento de plantas de cevada em condições de fosfato insolúvel, indicando que estas bactérias podem ser utilizadas como inoculantes, contribuindo para a redução da quantidade de fertilizantes aplicados no cultivo da cevada.

The occurrence of associations between bacteria and plant roots may be beneficial, neutral or detrimental. Plant growth promoting (PGP) bacteria form a heterogeneous group of beneficial microorganisms that can be found in the rhizosphere, the root surfaces or in association with host plant. The aim of this study was to isolate and characterize PGP bacteria associated to barley plants (Hordeum vulgare L.) aiming a future application as agricultural inoculant. One hundred and sixty bacterial strains were isolated from roots or rhizospheric soil of barley based on their growth in nitrogen-free selective media. They were evaluated for their ability to produce indolic compounds (ICs) and siderophores, and to solubilize tricalcium phosphate inin vitro assays. Most of them (74%) were able to synthesize ICs in the presence of the precursor L-tryptophan, while 57% of the isolates produced siderophores in Fe-limited liquid medium, and 17% were able to solubilize tricalcium phosphate. Thirty-two isolates possessing different PGP characteristics were identified by partial sequencing of their 16S rRNA gene. Strains belonging to Cedecea andMicrobacterium genera promoted the growth of barley plants in insoluble phosphate conditions, indicating that these bacteria could be used as bioinoculants contributing to decrease the amount of fertilizers applied in barley crops.

https://doi.org/10.1590/1676-06032015010514 3403 downloads

12.

SOIL FUNGISTASIS AGAINST FUSARIUM GRAMINEARUM UNDER DIFFERENT CROP MANAGEMENT SYSTEMS
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Lisboa, Bruno Brito

; Bayer, Cimélio

; Passaglia, Luciane Maria Pereira

; Camargo, Flávio Anastácio de Oliveira

; Beneduzi, Anelise

; Ambrosini, Adriana

; Vargas, Luciano Kayser

Revista Brasileira de Ciência do Solo

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Fev 2015, Volume 39 Nº 1 Páginas 69 - 77

Resumo: Pt En | Texto: Pt En | PDF: Pt | PDF: En

O manejo, em termos de preparo e sistemas de culturas, exerce forte influência sobre as propriedades do solo; e essas, por sua vez, condicionam o seu potencial supressivo a doenças de plantas. Nesse contexto, a fungistase é um dos componentes da supressividade, sendo um processo mediado pela microbiota do solo. Este trabalho teve como objetivo avaliar a influência de diferentes sistemas de manejo sobre a fungistase ao fungo fitopatogênico Fusarium graminearum, a sua relação com o perfil bacteriano do solo e os possíveis mecanismos de ação envolvidos no processo. As avaliações foram realizadas a partir de amostras de um Argissolo Vermelho distrófico, coletadas em um experimento de manejo de longa duração, conduzido sob plantio direto e preparo convencional e cultivado com os sistemas de culturas aveia + vica/milho + caupi, vica/milho e aveia/milho. A fungistase do solo foi avaliada em termos de redução do crescimento radial do fungo testado. O perfil bacteriano foi avaliado pelo polimorfismo do espaço intergênico do 16S rRNA (RISA). Foram obtidos 120 isolados bacterianos, que foram avaliados quanto à antibiose e à produção de compostos voláteis e de sideróforos. As amostras provenientes de plantio direto apresentaram maior fungistase a F. graminearum, reduzindo acentuadamente o desenvolvimento do patógeno. Também foi observada maior inibição do patógeno nas amostras de solo cultivadas sob o sistema aveia + vica/milho + caupi, enquanto o sistema aveia/milho foi o menos antagonista. O perfil genético bacteriano do solo também foi influenciado pelos sistemas de manejo, havendo semelhança entre os sistemas mais antagonistas. Embora não tenha sido identificada uma relação entre os sistemas de manejo e as características dos isolados, pode-se concluir que a antibiose e a produção de sideróforos foram os mecanismos que mais contribuíram para a fungistase.

Soil management, in terms of tillage and cropping systems, strongly influences the biological properties of soil involved in the suppression of plant diseases. Fungistasis mediated by soil microbiota is an important component of disease-suppressive soils. We evaluated the influence of different management systems on fungistasis against Fusarium graminearum, the relationship of fungistasis to the bacterial profile of the soil, and the possible mechanisms involved in this process. Samples were taken from a long-term experiment set up in a Paleudult soil under conventional tillage or no-tillage management and three cropping systems: black oat (Avena strigose L.) + vetch (Vicia sativa L.)/maize (Zea mays L.) + cowpea (Vigna sinensis L.), black oat/maize, and vetch/maize. Soil fungistasis was evaluated in terms of reduction of radial growth of F. graminearum, and bacterial diversity was assessed using ribosomal intergenic spacer analysis (RISA). A total of 120 bacterial isolates were obtained and evaluated for antibiosis, and production of volatile compounds and siderophores. No-tillage soil samples showed the highest level of F. graminearum fungistasis by sharply reducing the development of this pathogen. Of the cropping systems tested, the vetch + black oat/maize + cowpea system showed the highest fungistasis and the oat/maize system showed the lowest. The management system also affected the genetic profile of the bacteria isolated, with the systems from fungistatic soils showing greater similarity. Although there was no clear relationship between soil management and the characteristics of the bacterial isolates, we may conclude that antibiosis and the production of siderophores were the main mechanisms accounting for fungistasis.

https://doi.org/10.1590/01000683rbcs20150683 2121 downloads

13.

Cultivable bacteria isolated from apple trees cultivated under different crop systems: Diversity and antagonistic activity against Colletotrichum gloeosporioides
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Passos, João Frederico M. dos

; Costa, Pedro B. da

; Costa, Murilo D.

; Zaffari, Gilmar R.

; Nava, Gilberto

; Boneti, José Itamar

; Oliveira, Andréia Mara R. de

; Passaglia, Luciane M.P.

Genetics and Molecular Biology

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Set 2014, Volume 37 Nº 3 Páginas 560 - 572

Resumo: En | Texto: En | PDF: En

This study evaluated the diversity of cultivable plant growth-promoting (PGP) bacteria associated with apple trees cultivated under different crop management systems and their antagonistic ability against Colletotrichum gloeosporioides. Samples of roots and rhizospheric soil from apple trees cultivated in organic and conventional orchards in southern Brazil were collected, together with soil samples from an area never used for agriculture (native field). Bacteria were identified at the genus level by PCR-RFLP and partial sequencing of the 16S rRNA, and were evaluated for some PGP abilities. The most abundant bacterial genera identified were Enterobacter (27.7%), Pseudomonas (18.7%), Burkholderia (13.7%), and Rahnella (12.3%). Sixty-nine isolates presented some antagonist activity against C. gloeosporioides. In a greenhouse experiment, five days after exposure to C. gloeosporioides, an average of 30% of the leaf area of plants inoculated with isolate 89 (identified as Burkholderia sp.) were infected, whereas 60 to 73% of the leaf area of untreated plants was affected by fungal attack. Our results allowed us to infer how anthropogenic activity is affecting the bacterial communities in soil associated with apple tree crop systems, and to obtain an isolate that was able to delay the emergence of an important disease for this culture.

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14.

Genetic diversity and symbiotic compatibility among rhizobial strains and Desmodium incanum and Lotus spp. plants
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Granada, Camille E

; Strochein, Marcos

; Vargas, Luciano K

; Bruxel, Manuela

; Sá, Enilson Luiz Saccol de

; Passaglia, Luciane M.P

Genetics and Molecular Biology

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Jun 2014, Volume 37 Nº 2 Páginas 396 - 405

Resumo: En | Texto: En | PDF: En

This work aimed to evaluate the symbiotic compatibility and nodulation efficiency of rhizobia isolated from Desmodium incanum, Lotus corniculatus, L. subbiflorus, L. uliginosus and L. glaber plants by cross-inoculation. Twelve reference strains and 21 native isolates of rhizobia were genetically analyzed by the BOX-PCR technique, which showed a high genetic diversity among the rhizobia studied. The isolates were also characterized based on their production of indolic compounds and siderophores, as well as on their tolerance to salinity. Fifteen of the 33 rhizobia analyzed were able to produce indolic compounds, whereas 13 produced siderophores. All the tested rhizobia were sensitive to high salinity, although some were able to grow in solutions of up to 2% NaCl. Most of the native rhizobia isolated from L. uliginosus were able to induce nodulation in all plant species studied. In a greenhouse experiment using both D. incanum and L. corniculatus plants, the rhizobia isolate UFRGS Lu2 promoted the greatest plant growth. The results demonstrate that there are native rhizobia in the soils of southern Brazil that have low host specificity and are able to induce nodulation and form active nodules in several plant species.

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15.

Characterization of plant growth-promoting bacteria inhabiting Vriesea gigantea Gaud. and Tillandsia aeranthos (Loiseleur) L.B. Smith (Bromeliaceae)
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Giongo, Adriana

; Beneduzi, Anelise

; Gano, Kelsey

; Vargas, Luciano Kayser

; Utz, Laura

; Passaglia, Luciane Maria Pereira

Biota Neotropica

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Set 2013, Volume 13 Nº 3 Páginas 80 - 85

Resumo: Pt En | Texto: Pt En | PDF: Pt | PDF: En

Microrganismos que habitam o interior e a superfície podem fornecer substancias essenciais ao crescimento das plantas, como fitormônios e nutrientes essenciais. O presente trabalho teve como objetivo isolar e caracterizar as bactérias da filosfera, do ambiente endofítico e a água de tanque associadas à Vriesea gigantea e Tillandsia aeranthos. As bactérias foram submetidas a testes de verificação de produção de sideróforos e de ácido indol acético (AIA), solubilização de fosfatos, e a presença do gene nif H. A diversidade genética dos isolados bacterianos foi analisada por rep-PCR. Sessenta e oito microrganismos foram isolados de 3 microambientes distintos de V. gigantea e de 2 microambientes de T. aeranthos. A maioria das bactérias isoladas foram bacilos formadores de esporos, gram-positivos. Todos os isolados produziram AIA in vitro na presença de quantidades pequenas de triptofano. Mais de 70% das bactérias analisadas produziram sideróforos, solubilizaram fosfatos e possuíam o gene nif H. Não foi possível distinguir grupos definidos de microrganismos baseados no microhabitat e na espécie de bromélia de onde foram isolados usando rep-PCR. A água do tanque apresentou maior diversidade microbiana quando comparada com a filosfera e o ambiente endofítico, provavelmente devido à alta concentração de nutrientes, que promove um ambiente favorável para o desenvolvimento de comunidades microbianas complexas.

Microorganisms that live inside and around a plant can supply it with essential substances, such as phytohormones and essential nutrients. The present investigation aimed to isolate and characterize the phyllosphere, the endophytic, and the water tank bacteria associated with Vriesea gigantea and Tillandsia aeranthos. The bacteria were tested for siderophore and indole-3-acetic acid (IAA) production, phosphate solubilization, and presence of the nif H gene. Genetic diversity of the bacterial isolates was evaluated by rep-PCR. Sixty-eight bacterial strains were isolated from 3 different microhabitats of V. gigantea and from 2 microhabitats of T. aeranthos bromeliad plants. Gram-positive, spore-forming bacilli comprised most bacterial isolates. All isolates produced IAA in vitro in presence of very low amounts of tryptophan. More than 70% of the evaluated bacteria presented the ability of siderophore production and phosphate solubilization, and possessed the nif H gene. It was not possible to distinguish well-defined groups of isolates based on the bromeliad species and microhabitat they inhabit using genetic characterization by rep-PCR. Water tanks presented the most abundant diversity compared with phyllosphere and endophytes, probably due to the high nutrient concentration, which promotes an ideal environment for complex microbial communities.

https://doi.org/10.1590/S1676-06032013000300010 3523 downloads

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