105 research outputs found
Epicoccum nigrum P16, a Sugarcane Endophyte, Produces Antifungal Compounds and Induces Root Growth
Background: Sugarcane is one of the most important crops in Brazil, mainly because of its use in biofuel production. Recent studies have sought to determine the role of sugarcane endophytic microbial diversity in microorganism-plant interactions, and their biotechnological potential. Epicoccum nigrum is an important sugarcane endophytic fungus that has been associated with the biological control of phytopathogens, and the production of secondary metabolites. In spite of several studies carried out to define the better conditions to use E. nigrum in different crops, little is known about the establishment of an endophytic interaction, and its potential effects on plant physiology. Methodology/Principal Findings: We report an approach based on inoculation followed by re-isolation, molecular monitoring, microscopic analysis, plant growth responses to fungal colonization, and antimicrobial activity tests to study the basic aspects of the E. nigrum endophytic interaction with sugarcane, and the effects of colonization on plant physiology. The results indicate that E. nigrum was capable of increasing the root system biomass and producing compounds that inhibit the in vitro growth of sugarcane pathogens Fusarium verticillioides, Colletotrichum falcatum, Ceratocystis paradoxa, and Xanthomomas albilineans. In addition, E. nigrum preferentially colonizes the sugarcane surface and, occasionally, the endophytic environment. Conclusions/Significance: Our work demonstrates that E. nigrum has great potential for sugarcane crop application because it is capable of increasing the root system biomass and controlling pathogens. The study of the basic aspects of the interaction of E. nigrum with sugarcane demonstrated the facultative endophytism of E. nigrum and its preference for the phylloplane environment, which should be considered in future studies of biocontrol using this species. In addition, this work contributes to the knowledge of the interaction of this ubiquitous endophyte with the host plant, and also to a better use of microbial endophytes in agriculture.State of Sao Paulo Research Foundation (FAPESP)FAPESP (State of Sao Paulo Research Foundation) [02/14143-3, 10/08286-2]Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq
Inducing Ni Sensitivity in the Ni Hyperaccumulator Plant Alyssum inflatum Nyárády (Brassicaceae) by Transforming with CAX1, a Vacuolar Membrane Calcium Transporter
The importance of calcium in nickel tolerance was studied in the nickel hyperaccumulator plant Alyssum inflatum by gene transformation of CAX1, a vacuolar membrane transporter that reduces cytosolic calcium. CAX1 from Arabidopsis thaliana with a CaMV35S promoter accompanying a kanamycin resistance gene was transferred into A. inflatum using Agrobacterium tumefaciens. Transformed calli were subcultured three times on kanamycin-rich media and transformation was confirmed by PCR using a specific primer for CAX1. At least 10 callus lines were used as a pool of transformed material. Both transformed and untransformed calli were treated with varying concentrations of either calcium (1–15 mM) or nickel (0– 500 lM) to compare their responses to those ions. Increased external calcium generally led to increased callus biomass, however, the increase was greater for untransformed callus. Further, increased external calcium led to increased callus calcium concentrations. Transformed callus was less nickel tolerant than untransformed callus: under increasing nickel concentrations callus relative growth rate was significantly less for transformed callus. Transformed callus also contained significantly less nickel than untransformed callus when exposed to the highest external nickel concentration (200 lM). We suggest that transformation with CAX1 decreased cytosolic calcium and resulted in decreased nickel tolerance. This in turn suggests that, at low cytosolic calcium concentrations, other nickel tolerance mechanisms (e.g., complexation and vacuolar sequestration) are insufficient for nickel tolerance. We propose that high cytosolic calcium is an important mechanism that results in nickel tolerance by nickel hyperaccumulator plants
Synergistic degradation of diazo dye Direct Red 5B by Portulaca grandiflora and Pseudomonas putida
Plants and bacterial consortium of Portulaca grandiflora and
Pseudomonas putida showed complete decolorization of a sulfonated
diazo dye Direct Red 5B within 72 h, while in vitro cultures of P.
grandiflora and P. putida independently showed 92 and 81 %
decolorization within 96 h, respectively. A significant induction in
the activities of lignin peroxidase, tyrosinase, 2,6-dichlorophenol
indophenol reductase and riboflavin reductase was observed in the roots
of P. grandiflora during dye decolorization; whereas, the activities of
laccase, veratryl alcohol oxidase and 2,6-dichlorophenol indophenol
reductase were induced in the cells of P. putida. Plant and bacterial
enzymes in the consortium gave an enhanced decolorization of Direct Red
5B synergistically. The metabolites formed after dye degradation
analyzed by UV-Vis spectroscopy, Fourier transformed infrared
spectroscopy and high performance liquid chromatography confirmed the
biotransformation of Direct Red 5B. Differential fate of metabolism of
Direct Red 5B by P. grandiflora, P. putida and their consortium were
proposed with the help of gas chromatography-mass spectroscopy
analysis. P. grandiflora metabolized the dye to give
1-(4-diazenylphenyl)-2-phenyldiazene, 7-(benzylamino)
naphthalene-2-sulfonic acid, 7-aminonaphthalene-2-sulfonic acid and
methylbenzene. P. putida gave 4-hydroxybenzenesulfonic acid and
4-hydroxynaphthalene-2-sulfonic acid and benzamide. Consortium showed
the formation of benzenesulfonic acid, 4-diazenylphenol,
6-aminonaphthalen-1-ol, methylbenzene and naphthalen-1-ol. Consortium
achieved an enhanced and efficient degradation of Direct Red 5B.
Phytotoxicity study revealed the nontoxic nature of metabolites formed
after parent dye degradation. Use of such combinatorial systems of
plant and bacteria could prove to be an effective and efficient
strategy for the removal of textile dyes from soil and waterways
Influência da qualidade de luz e silÃcio no crescimento in vitro de orquÃdeas nativas e hÃbridas
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