Infecção por Fusarium graminearum e Fusarium verticillioides em sementes de milho

The previous knowledge of the infection process and pathogens behavior, for evaluating the physiological potential of maize seeds, is essential for decision making on the final destination of lots that can endanger sowing. This research was carried out in order to study the minimum period required for maize seeds contamination by Fusarium graminearum Schwabe and Fusarium verticillioides (Sacc.) Nirenberg, as well as these pathogens influence on seed germination and vigor, by using the cold test. Three maize seeds hybrids, kept in contact with the pathogens for different periods, were evaluated with and without surface disinfection. After determining the most suitable period, new samples were contaminated by F. graminearum and F. verticillioides, under different infection levels, and subjected to germination tests in sand. The cold test was conducted with healthy and contaminated seeds, at different periods, in a cold chamber. The contact of maize seeds with F. graminearum and F. verticillioides for 16 hours was enough to cause infection. F. graminearum and F. verticillioides did not affect the maize seeds germination, however, F. graminearum reduced the vigor of seeds lots.

Comparison of lipase production on crambe oil and meal by Fusarium sp (Gibberella fujikuroi complex)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Purification and biochemical characterization of an alkaline pectin lyase from Fusarium decemcellulare MTCC 2079 suitable for Crotolaria juncea fiber retting

An extracellular pectin lyase secreted by Fusarium decemcellulare MTCC 2079 under solid state fermentation condition has been purified to electrophoretic homogeniety by using ammonium sulfate fractionation, carboxymethyl cellulose and gel filtration (Sephadex G-100) column chromatographies. The purified enzyme showed single protein band corresponding to molecular mass 45 +/- 01 kDa on sodium dodecyl sulfate polyacrylamide gel electrophoresis. The enzyme had maximum activity at pH 9.0 and showed maximum stability in the pH range of 9.0-12.0. The optimum temperature of the purified enzyme was 50 degrees C and it showed maximum stability upto 40 degrees C. The energy of activation for the thermal denaturation (Ea) was 59.06 kJ mol(-1) K-1. The K-m and k(cat) values using citrus pectin as the substrate were 0.125mgml(-1) and 72.9 s(-1) in 100mM sodium carbonate buffer pH 9.0 at 50 degrees C. The biophysical studies on pectin lyase showed that its secondary structure belongs to alpha+beta class of protein with comparatively less of beta-sheets. Purified pectin lyase showed efficient retting of Crotolaria juncea fibers.

Rhizospheric streptomycetes as potential biocontrol agents of Fusarium and Armillaria pine rot and as PGPR for Pinus taeda

Pinus taeda is one of the main timber trees in Brazil, occupying 1.8 million ha with an annual productivity of 25-30 m(3) ha(-1). Another important species is Araucaria angustifolia, belonging to the fragile Rainforest biome, which for decades has been a major source of timber in Brazil. Some diseases that affect the roots and/or the stem of these trees and cause "damping-off" of the seedlings, with economic and environmental losses for the forest sector, are caused by the plant pathogenic fungi Fusarium sp. or Armillaria sp. This research project intended to isolate actinobacteria from the Araucaria rhizosphere, which present an antagonistic effect against these fungi. After the selection of the best pathogen inhibitors, morphologic characteristics, enzyme production, and their effect on the growth of Pinus taeda were studied. The actinobacteria were tested for their antagonistic capacity against Fusarium sp. in Petri plates with PDA as substrate. The inhibition zone was measured after 3, 5, 7, and 10 days. Of all the isolates tested, only two of them maintained inhibition zones up to 4 mm for 10 days. The inhibition of Armillaria sp. was tested in liquid medium and also in Petri dishes through the evaluation of the number of the fungal rhizomorphs in dual culture with the actinobacteria. It was found that all five isolates were able to inhibit the rhizomorph production, with the best performance of the isolate A43, which was capable of inhibiting both fungi, Fusarium and Armillaria. In a greenhouse experiment, the effect of five isolates on the growth of Pinus taeda seedlings was tested. Plant height, stem diameter, root and shoot dry matter were determined. The Streptomyces isolate A43 doubled plant growth. These results may lead to the development of new technologies in the identification of still unknown bacterial metabolites and new management techniques to control forest plant diseases.

Identificação, caracterização e avaliação da patogenicidade de diferentes isolados de fusarium spp. para o controle de thaumastocoris peregrinus (hemiptera: thaumastocoridae)

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Efeito do co2 sobre a qualidade nutricional, ferrugem e fusariose da alfafa

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Chicken fat and inorganic nitrogen source for lipase production by Fusarium sp. (Gibberella fujikuroi complex)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Supressividade a Fusarium oxysporum f. sp. cubense por produtos orgânicos

Pós-graduação em Agronomia (Proteção de Plantas) - FCA

Resposta enzimática, fisiológica e produtiva do tomateiro e desempenho de porta enxertos resistentes à murcha bacteriana

Pós-graduação em Agronomia (Horticultura) - FCA

Produção, imobilização e aplicação de lipase de Fusarium verticillioides

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Comportamento do maracuajazeiro amarelo, variedade Afruvec, ante uma população de Fusarium solani, agente causal da podridão do colo

The objective of the present work was to verify the behavior of yellow passion fruit, Afruvec variety, in relation to a population of Fusarium solani, obtained from this crop. The experimental delineation was random blocks, containing 10 treatments [9 isolates and 1 control treatment], with 4 repetitions, each plot being represented by a vase containing a plant. A disk of culture medium colonized by each isolate of the fungus was inoculated in the wounded collar region of the plants of the Afruvec variety two months after sowing. The appraised parameters were: the pathogenicity, the incidence (number of dead plants) and the severity of the disease (length of the lesion in the collar region), until 60 days after inoculation. The Afruvec variety was susceptible to the fungus and also presented variability as to the severity of the disease and incidence in relation to the different isolates. The population of the fungus showed variability in regard to aggressiveness. In light of the evidence of genetic diversity in the F. solani population, it is also suggested, in the tests of selection of materials to the pathogen, that these materials should be evaluated in different places with a history of the disease or inoculation with a pool of isolates of the fungus, in order to know the wide resistance of the genotype to the pathogen.

Trichoderma harzianum expressed sequence tags for identification of genes with putative roles in mycoparasitism against Fusarium solani

The plant pathogen Fusarium solani causes a disease root rot of common bean (Phaseolus vulgaris) resulting in great losses of yield in irrigated areas of the Southeast and Midwest regions of Brazil. Species of the genus Trichoderma have been used in the biological control of this pathogen as an alternative to chemical control. To gain new insights into the biocontrol mechanism used by Trichoderma harzianum against the phytopathogenic fungus, Fusarium solani, we performed a transcriptome analysis using expressed sequence tags (ESTs) and quantitative real-time PCR (RT-qPCR) approaches. A cDNA library from T. harzianum mycelium (isolate ALL42) grown on cell walls of F. solani (CWFS) was constructed and analyzed. A total of 2927 high quality sequences were selected from 3845 and 37.7% were identified as unique genes. The Gene Ontology analysis revealed that the majority of the annotated genes are involved in metabolic processes (80.9%), followed by cellular process (73.7%). We tested twenty genes that encode proteins with potential role in biological control. RT-qPCR analysis showed that none of these genes were expressed when T. harzianum was challenged with itself. These genes showed different patterns of expression during in vitro interaction between T. harzianum and F. solani. (C) 2012 Elsevier Inc. All rights reserved.

Endophytic fungi from Vitis labrusca L. ('Niagara Rosada') and its potential for the biological control of Fusarium oxysporum

We investigated the diversity of endophytic fungi found on grape (Vitis labrusca cv. Niagara Rosada) leaves collected from Salesopolis, SP, Brazil. The fungi were isolated and characterized by amplified ribosomal DNA restriction analysis, followed by sequencing of the ITS1-5.8S-ITS2 rDNA. In addition, the ability of these endophytic fungi to inhibit the grapevine pathogen Fusarium oxysporum f. sp herbemontis was determined in vitro. We also observed that the climatic factors, such as temperature and rainfall, have no effect on the frequency of infection by endophytic fungi. The endophytic fungal community that was identified included Aporospora terricola, Aureobasidium pullulans, Bjerkandera adusta, Colletotrichum boninense, C. gloeosporioides, Diaporthe helianthi, D. phaseolorum, Epicoccum nigrum, Flavodon flavus, Fusarium subglutinans, F. sacchari, Guignardia mangiferae, Lenzites elegans, Paraphaeosphaeria pilleata, Phanerochaete sordida, Phyllosticta sp, Pleurotus nebrodensis, Preussia africana, Tinctoporellus epiniltinus, and Xylaria berteri. Among these isolates, two, C. gloeosporioides and F. flavus, showed potential antagonistic activity against F. oxysporum f. sp herbemontis. We suggest the involvement of the fungal endophyte community of V. labrusca in protecting the host plant against pathogenic Fusarium species. Possibly, some endophytic isolates could be selected for the development of biological control agents for grape fungal disease; alternatively, management strategies could be tailored to increase these beneficial fungi.

Identification of differentially expressed genes from Trichoderma harzianum during growth on cell wall of Fusarium solani as a tool for biotechnological application

Background: The species of T. harzianum are well known for their biocontrol activity against many plant pathogens. However, there is a lack of studies concerning its use as a biological control agent against F. solani, a pathogen involved in several crop diseases. In this study, we have used subtractive library hybridization (SSH) and quantitative real-time PCR (RT-qPCR) techniques in order to explore changes in T. harzianum genes expression during growth on cell wall of F. solani (FSCW) or glucose. RT-qPCR was also used to examine the regulation of 18 genes, potentially involved in biocontrol, during confrontation between T. harzianum and F. solani. Results: Data obtained from two subtractive libraries were compared after annotation using the Blast2GO suite. A total of 417 and 78 readable EST sequence were annotated in the FSCW and glucose libraries, respectively. Functional annotation of these genes identified diverse biological processes and molecular functions required during T. harzianum growth on FSCW or glucose. We identified various genes of biotechnological value encoding to proteins which function such as transporters, hydrolytic activity, adherence, appressorium development and pathogenesis. Fifteen genes were up-regulated and sixteen were down-regulated at least at one-time point during growth of T. harzianum in FSCW. During the confrontation assay most of the genes were up-regulated, mainly after contact, when the interaction has been established. Conclusions: This study demonstrates that T. harzianum expressed different genes when grown on FSCW compared to glucose. It provides insights into the mechanisms of gene expression involved in mycoparasitism of T. harzianum against F. solani. The identification and evaluation of these genes may contribute to the development of an efficient biological control agent.

Bioactive extracts and chemical constituents of two endophytic strains of Fusarium oxysporum

Ethyl acetate extracts of cultures grown in liquid Czapek and on solid rice media of the fungal endophyte Fusarium oxysporum SS46 isolated from the medicinal plant Smallanthus sonchifolius (Poepp.) H. Rob., Asteraceae, exhibited considerable cytotoxic activity when tested in vitro against human cancer cells. Chromatographic separation yielded anhydrofusarubin (1) and beauvericin (2) that were identified based on their ¹H and 13C NMR data. Compounds 1 and 2 showed the strongest cytotoxic activity against different cancer cell lines. Compound 2 also showed promising activity against Leishmania braziliensis. Hexanic extract of F. oxysporum SS50 grown on solid rice media also afforded a mixture of compounds that displayed cytotoxic activity against different cancer cell lines. Chemical analysis of the mixture of compounds, investigated by gas chromatography-mass spectrometry (GC-MS), showed that there was a predominance of methyl esters of fatty acids and alkanes.