43,889 research outputs found

    Aislamiento de Gluconacetobacter a partir de cultivos de ca√Īa

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    Se recolectaron muestras de hojas, tallo y ra√≠z de cultivos de ca√Īa provenientes del municipio de Sup√≠a (Caldas). Las colonias presuntivas del g√©nero Gluconacetobacter fueron repicadas en agar papa dextrosa para realizaci√≥n de pruebas bioqu√≠micas. Se evaluaron los siguientes par√°metros bioqu√≠micos: coloraci√≥n de Gram, fermentaci√≥n de carbohidratos, catalasa, licuefacci√≥n de gelatina, movilidad y utilizaci√≥n de citrato. Como resultados del presente trabajo se demostr√≥ la presencia de Gluconacetobacter spp. en cultivos caldenses de ca√Īa de az√ļcar. Asimismo, se estandarizaron metodolog√≠as para el aislamiento de bacterias fijadoras de nitr√≥geno como G. diazotrophicus. Lo anterior permitir√° explorar el potencial de este tipo de microorganismos con miras a desarrollar productos microbianos innovadores y adaptados a las condiciones ambientales locales para la promoci√≥n del crecimiento de diferentes cultivos de importancia econ√≥mica en Colombia.Samples were collected from leaves, stem and roots of sugarcane crops located in the municipality of Sup√≠a (Caldas, Colombia). The presumptive colonies of the genus Gluconacetobacter were isolated in potato dextrose agar for biochemical testing. Thefollowing biochemical parameters were assessed: Gram stain, fermentation of carbohydrates, catalase, gelatin liquefaction, mobility and citrate use. The results demonstrated the presence of Gluconacetobacter spp. in sugarcane crops located in Caldas. In addition, methodologies for isolation of nitrogen fixing bacteria such G. diazotrophicus were standardized. This will allow the exploration of the potential of these microorganism in order to develop innovative microbial products adapted to local environmental conditions for promoting the growth of different Colombian crops with economic importance.Departamento Administrativo de Ciencia, Tecnolog√≠a e Innovaci√≥n [CO] Colciencias1127-521-28333Obtenci√≥n y evaluaci√≥n de un promotor para el crecimiento de cultivos de tomate y zanahoria a base de Gluconacetobacter diazotrophicusn

    Efficacy of thiophanate methyl against red rot of sugarcane

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    The control of sugarcane red rot was studied in model experiments with carbendazim and thiophanate methyl. In axenic cultures carbendazim inhibited the pathogen more efficiently than thiophanate methyl (MIC 1 and 100 mgL-1, respectively). However, under greenhouse conditions, the reverse picture was revealed. Carbendazim, the metabolite of thiophanate methyl, exhibited lower efficacy against red rot disease than its precursor. Fungicides applied before infection reduced the disease incidence and improved both germination of setts and plant survival. Soaking of sugarcane setts in a 0.25% suspension of fungicides for 24 h before planting was found to be more effective in controlling debris-borne infection than soaking for 1 h period at elevated doses. The persistence of effects both on disease incidence and on promoting plant growth can be observed up to 60 days after planting (DAP)

    Gluconacetobacter diazotrophicus in tropical tomato (Solanum lycopersicum L.) and sugarcane crops (Saccharum officinarum L.) from the West Central region of Colombia

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    Background and aims Gluconacetobacter diazotrophicus is a plant growth-promoting bacterium (PGPB) that is endophytic and associated with sugarcane in Brazil. This study aims to determine the presence of G. diazotrophicus bacteria in sugarcane and tomato crops in Colombia. Methods Bacteria were isolated from roots, stems and leaf tissues and identified using phenotypic and biochemical evaluations and PCR assays. Isolates were characterized by their production of indole compounds, nitrogenase activity, and phosphorus solubilization. Results 100% of isolates obtained solubilize phosphorus, produce indole compounds in the presence of tryptophan, and exhibit nitrogenase activity. The isolates from sugarcane that were selected belong to the species G. diazotrophicus. Conclusions These results constitute the first report confirming the natural presence of G. diazotrophicus in Colombia. This finding has ecological significance and will advance research towards identifying the potential use of this bacterium in regional crops.Departamento Administrativo de Ciencia, Tecnología e Innovación [CO] Colciencias1127-521-28333Obtención y evaluación de un promotor para el crecimiento de cultivos de tomate y zanahoria a base de Gluconacetobacter diazotrophicusn

    Production of secondary metabolites by strains of Pseudomonas spp. antagonistic to Colletotrichum falcatum causing red rot disease in sugarcane

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    Production of secondary metabolites such as siderophores, indole acetic acid, salicylic acid and antibiotics phenazine, pyocyanine and 2,4-diacetyl phloroglucinol by Pseudomonas spp. associated with induced systemic resistance (ISR) activity in sugarcane against red rot disease was assessed. Many of the strains have been found to produce these metabolites and antibiotics in the culture medium. The antibiotics were separated and identified by thin layer chromatography by running the purified metabolites from the reference strains. The bacterial strains varied in their capability to produce the metabolites. The purified compounds were tested for their antifungal activity against the red rot pathogen Colletotrichum falcatum. Most of the purified metabolites have completely arrested conidial germination and mycelial growth of the fungus. The results suggest that the metabolites production may play a role in antagonism/induced systemic resistance against the pathogen

    Effect of Phytotoxin of Colletotrichum falcatum Went. (Physalospora tucumanensis) on Sugarcane in Tissue Culture

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    A phytotoxin produced by the sugarcane red rot fungus, Colletotrichum falcatum Went. was partially purified and its effects studied on sugarcane callus development, plantlet differentiation and shoot growth in tissue culture. The findings indicate that all the above attributes were markedly reduced by the fungal toxin. Potential for the possible use of the toxin to produce red rot resistant sugarcane genotypes by pathogen toxin induced somaclonal variation is examined

    Biocontrolo de fungos fitopatogénicos importantes para a economia do cacau e da oliveira

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    Tese de Doutoramento (Programa Doutoral em Biologia Molecular e Ambiental - Especialidade em Biologia Molecular)Plant diseases caused by fungal pathogens constitute an increasing threat to food production and security. This is the case of Witches‚Äô Broom Disease (WBD) of cacao, caused by the basidiomycete Moniliophthora perniciosa, and of Olive Anthracnose (OA), caused by a consortium of Colletotrichum gloeosporioides and C. acutatum species complexes, which seriously impact the economy. Both share the lack of effective containment methods. The use of chemical fungicides is increasingly more precarious and restricted. More effective eco-friendly methods are required, such as the use of biocontrol agents. This work aimed to evaluate the ability of yeasts to antagonize the fungal causal agents of both diseases. A group of yeasts originating from Brazilian sugarcane-based fermentation industries were tested against M. perniciosa. Two isolates from cacha√ßa production fermentation and one of the most used strains in bioethanol production, efficiently kill six strains of M. perniciosa in vitro. Antagonistic ability is maintained in non-optimal conditions. Microscopy analysis showed that fungal cells die upon contact with these yeasts, which physically attach and fuse to the mycelium and drain the cells, in what appears like a yeast predacious behaviour. Two further observations revealed the formation of connections between yeast and fungal cells, as well as fimbriae-like connections between yeast cells. These results agree in that, at a distance, only the proliferation of mycelia is diverted through the probable secretion of a non-volatile agar diffusible compound. Several proteins were identified specifically secreted by fungi and yeasts in single culture and co-culture. The methodology now developed was further used to study the antagonism of yeasts against the OA-causing Colletotrichum sp.. The same group of fermentative yeasts were tested along with others originating from the olive biome in Portuguese orchards. One of these last strains showed a promising antagonistic potential, by inhibiting the growth of the three fungal strains in all the conditions tested. Moreover, the possibility of using vinasse, a waste product from sugarcane bioethanol production process, to control the development of M. perniciosa was also evaluated. Immersing or spraying the mycelium with vinasse either kills the fungus or impedes its proliferation. This effect is not extensive the OA-causing fungi. The results support the exploration of microbial biodiversity of the infected plant-associated biome to generate greener and more sustainable alternatives to contain phytopathogens like those causing WBD and OA, contributing to alleviate the socio-economic impact of these diseases.Fitopatologias causadas por fungos s√£o uma amea√ßa crescente √† produ√ß√£o e seguran√ßa alimentares. √Č o caso da doen√ßa da Vassoura-de-bruxa (VB) do cacau, causada pelo fungo Moniliophthora perniciosa, e da Antracnose da oliveira (AO), causada pelos complexos de esp√©cies Colletotrichum gloeosporioides e C. acutatum, que se tornaram um risco para a economia, por n√£o haver m√©todos eficazes de conten√ß√£o. O uso de fungicidas qu√≠micos √© cada vez mais ineficaz e mais restrito, pelo que √© necess√°rio encontrar alternativas mais amigas do ambiente, como por exemplo a utiliza√ß√£o de biocidas. Este trabalho teve como objetivo avaliar a capacidade de leveduras para antagonizar os fungos causadores destas doen√ßas. Um grupo de leveduras proveniente da fermenta√ß√£o de caldo-de-cana no Brasil foi testado contra M. perniciosa. Dois isolados do processo de produ√ß√£o de cacha√ßa e uma das leveduras mais utilizadas na produ√ß√£o industrial de bioetanol matam eficientemente 6 estirpes de M. perniciosa, in vitro. O antagonismo mant√©m-se em condi√ß√Ķes adversas. Observa√ß√Ķes de microscopia confirmaram que o fungo morre em contacto com as leveduras que aderem e se fundem com o mic√©lio, esvaziando-o, no que parece ser um comportamento predat√≥rio. Al√©m disso, observou-se a exist√™ncia de conex√Ķes entre c√©lulas de levedura e do mic√©lio, e entre c√©lulas de levedura entre si. Isto concorda com o facto de, √† dist√Ęncia, haver apenas redireccionamento do desenvolvimento do mic√©lio, atrav√©s da difus√£o de um composto n√£o-vol√°til, tendo sido verificado que os fungos e as leveduras segregam prote√≠nas diferentes em cultura simples ou em co-cultura. O m√©todo desenvolvido neste trabalho foi aplicado para verificar o antagonismo de leveduras contra os agentes causadores da AO. O mesmo conjunto de leveduras fermentativas foi testado, em confronto com estirpes provenientes do bioma de olivais portugueses. Uma destas √ļltimas leveduras mostrou grande potencial antagonista contra 3 estirpes de Colletotrichum sp. em todas as condi√ß√Ķes testadas. Adicionalmente, foi ensaiada com sucesso a utiliza√ß√£o da vinha√ßa, o res√≠duo denso e l√≠quido que resulta da destila√ß√£o do etanol ap√≥s a fermenta√ß√£o do caldo-de-cana, no controlo do desenvolvimento do M. perniciosa. A imers√£o ou a pulveriza√ß√£o do mic√©lio com vinha√ßa mata ou impede drasticamente a prolifera√ß√£o do fungo. Este efeito n√£o foi extens√≠vel aos fungos causadores da AO. Em suma, a explora√ß√£o da biodiversidade microbiana do bioma associado √†s plantas infetadas pode permitir desenvolver metodologias alternativas, mais amigas do ambiente e mais sustent√°veis, para a conten√ß√£o da presente progress√£o dos agentes fitopatog√©nicos, como os que provocam a VB e a AO, contribuindo para aliviar o impacto socioecon√≥mico destas doen√ßas.This work was supported by the strategic programme UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) funded by national funds through the FCT I.P. and by the ERDF through the COMPETE2020 - POCI, and the project EcoAgriFood (NORTE-01-0145-FEDER-000009), supported by the NORTE 2020 under the PORTUGAL 2020 Partnership Agreement through the European Regional Development Fund (ERDF). PF is a student of the Doctoral Programme in Applied and Environmental Microbiology (DP_AEM) and FCT grantee PD/BD/113810/2015. We thank Mariana Amorim-Rodrigues (FCT grant PD/BD/145354/2019) for the precious contributions with her research to the Chapter 4. We thank the Brazilian companies, Cerlev, Lda., Ouro Preto, MG, and Fermentec, Lda. Solu√ß√Ķes Tecnol√≥gicas e Industriais, Piracicaba, SP, as well as Professor Jo√£o Paulo Sampaio from the Portuguese Yeast Culture Collection/UCIBIO, NOVA, Portugal for kindly supplying the yeast strains used in this work. We also thank Professor Pedro Talhinhas, from LEAF - Linking Landscape, Environment, Agriculture and Food, ISA, Universidade de Lisboa, Portugal, for kindly supplying two of the fungal strains used in this work

    Genetic variability and character association studies among seed yield and yield component traitsin safflower (Carthamus tinctorius L.) genotypes

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    A study was carried out to assess the genetic variability and association among yield attributing traits in 60 different safflower genotypes over six environments. The pooled analysis of variance (ANOVA) revealed that all attributes had a considerable degree of variation.The pooled analysis of variability parameters revealed that the phenotypic coefficients of variation (PCV) was higher than the genotypic coefficients of variation (GCV)for all of the characteristics evaluated, indicating that experimental variance contributed to total variation.Petal yield/plant and seed yield/plant had the highest PCV and GCV followed by number of capitula/plant, number of seeds/capitula, height of insertion of first branch, hundred seed weight, number of primary branches/plant, length of longest primary branches, number of secondary branches and height up to main capitula.Number of capitula/plant, seed yield/plant, petal yield/plant, height of insertion of first branch, number of seeds per capitula, hundred seed weight, number of primary branches/plant, length of the longest primary branches, number of secondary branches, height upto main capitula, capitulum diameter and plant height all had high heritability and genetic advance as percent of mean. Seedyield/plant showed positive, significant and directcorrelation with number of capitula/plant, number of seeds/capitulum, height up to the main capitulum, plant height, number of primary branches/plant, capitulum diameter, and hundred seed weight.Number of capitula/planthad the maximum direct effect on grain yield/plant followed by number of seeds/capitulum, hundred seed weight and petal yield/plant. Hence selection of these traits would improve seed and petal yield in safflower breeding program

    Differential responses in some quinoa genotypes of a consortium of beneficial endophytic bacteria against bacterial leaf spot disease

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    Many effective plant-microbe interactions lead to biological changes that can stimulate plant growth and production. This study evaluated the effect of the interaction between quinoa (Chenopodium quinoa Willd.) and endophytic bacterial strains on differential responses under biotic stress. Four strains of endophytic bacteria were used to inoculate three quinoa genotypes. Endophytic bacteria, isolated from the endosphere of healthy genotypes of quinoa plants, were used to evaluate their biocontrol activity against Pseudomonas syringae on quinoa plants, which causes leaf spot disease, depending on some different parameters. Quinoa genotype plants were treated with four treatments: pathogenic bacteria only (T1), internal bacteria only (T2), pathogenic bacteria + endogenous bacteria (T3), and untreated as the control (T4). The results indicated that there was a significant difference between chlorophyll content index of infected plants without bioagent (untreated) compared to plants bio-inoculated with endophytic bacteria. The highest mean disease incidence was on the plants without bacterial inoculum (90, 80, and 100%) for quinoa genotypes G1, G2, and G3, respectively. The results showed that there were significant differences in the weight of grains/plant, as the value ranged from 8.1 to 13.3‚ÄČg when treated with pathogens (T1) compared to the treatment with pathogens and endogenous bacteria (T3), which ranged from 11.7 to 18.6‚ÄČg/plant. Decreases in total aromatic amino acids appeared due to the pathogen infection, by 6.3, 22.8, and 24.1% (compared to the control) in G1, G2, and G3, respectively. On the other hand, genotype G3 showed the highest response in the levels of total aromatic and total neutral amino acids. The endophytic strains promoted quinoa seedling growth mainly by improving nutrient efficiency. This improvement could not be explained by their ability to induce the production of amino acids, showing that complex interactions might be associated with enhancement of quinoa seedling performance by endophytic bacteria. The endophytic bacterial strains were able to reduce the severity of bacterial leaf spot disease by 30, 40, and 50% in quinoa genotypes G1, G2, and G3, respectively, recording significant differences compared to the negative control. The results indicated that, G1 genotype was superior in different performance indicators (pathogen tolerance index, yield injury %, superiority measure and relative performance) for grain weight/plant under pathogen infection condition when treated with endophyte bacteria. Based on this study, these bacterial strains can be used as a biotechnology tool in quinoa seedling production and biocontrol to diminish the severity of bacterial leaf spot disease
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