Controle de Fusarium moniliforme em sementes de milho por actinomicetos.

2003

Distribución de cepas de fusarium moniliforme productoras de fumonisina en B1 en maíz, cultivado en el estado de Nuevo León

Tesis (Maestría en Ciencias con Especialidad en microbiología) UANL

Supresión de Fusarium moniliforme por Bacillus thuringienses

Tesis (Doctorado en Ciencias con Especialidad en Microbiología) UANL

Bioprospecção de actinobactérias da rizosfera de milho (Zea mays L) e potencial de controle biológico de Fusarium moniliforme e Pythium aphanidermatum.

2008

Manejo de las tres principales plagas del sorgo (Sorghum bicolor L. Moench), gusano cogollero (Spodoptera frugiperda), mosquita del sorgo (Stenodiplosis sorghicola) y chinche pata de hoja (Leptoglossus zonatus) en época de postrera en la zona de ranchería, Chinandega 2003

El presente trabajo se realizó en la finca Santa Isabel ubicada en el municipio de Ranchería en el Km.20 carretera Chinandega–Somotillo en el departamento de Chinandega. Con el objetivo de evaluar el efecto de cuatro tratamientos sobre las poblaciones de Gusano Cogollero Spodoptera frugiperda (J. E. Smith), Mosquita del sorgo Stenodiplosis sorghicola (Coquillet) y Chinche pata de hoja Leptoglossus zonatus (Dallas), durante la época de postrera en los meses de Septiembre a Diciembre del 2003. Los tratamientos evaluados fueron Barrera viva de gandul-sorgo, Nim aceite, Beauveria bassiana en polvo y Diazinón, comparados con una parcela sin aplicación (testigo). Se utilizaron umbrales de 40 % de daño para el cogollero, dos individuos por panoja para la mosquita del sorgo y un individuo por panoja para el chinche pata de hoja, los muestreos se realizaron cada semana, iniciando desde la siembra hasta la cosecha. Se seleccionaron cinco sitios al azar en cada tratamiento y se registro el número de plagas observadas. Se realizaron dos aplicaciones, una primera aplicación en etapa vegetativa para los desfoliadores y una segunda aplicación en etapa reproductiva cuando mosquita del sorgo alcanzo el umbral establecido. No se encontró diferencia estadística entre los tratamientos, sin embargo en el tratamiento Nim aceite se presentaron menor número de plagas. Los mayores rendimiento se presentaron en el tratamiento Nim aceite y en el tratamiento Barrera viva (gandul-sorgo) con 2,370.6 Kg. /Ha y 2,234.7 Kg./Ha respectivamente. El análisis económico indica que el tratamiento Barrera viva (gandul- sorgo) presentó mayor rentabilidad con 170.97%. La especie de insecto plaga predominante en la zona de Ranchería, Chinandega durante la época de estudio fue Mocis latipes (gusano medidor) así mismo se presento la enfermedad conocida como moho del grano causada por un complejo de hongos Fusarium moniliforme sheldon y Curvularia lunata. En época de postrera 2003

Identificação dos principais fungos das sementes de trigo.

Procedimento para identificação dos fungos das sementes de trigo; Descrição diagnostica dos principais fungos das sementes de trigo; Sclerotium Tode; Rhizoctonia DC; Chaetomium Kunze; Pleospora Rabenh; Sporobolomyces Kluy. & Niel; Rhodotorula Harrison; Phoma Sacc.; Septoria tritici Rob; Stagonospora nodorum (Berk.) Cas. & Germ.; Stagonospora avenae (Frank) Bisset f. sp. triticae; Colletotrichum graminicola (Ces.) Wilson; Fusarium tricinctum (Corda) Sacc; Fusarium moniliforme Sheldon; Fusarium avenaceum (Fr.) Sacc; Fusarium acuminatum Ell. & Kellerm; Fusarium equiseti (Corda) Sacc.; Fusarium graminearum Schw.; Mucor Micheli; Rhizopus Ehrenb; Aspergillus Link.; Penicillium Link.; Alternaria Nees; Epicoccum Link; Cladosporium Link; Nigrospora Zimm; Curvularia Boedijn; Drechslera tritici-repentis (Died.) Drech; Bipolaris sorokiniana (Sacc. in Sorok.) Shoem; Chave sistemática dos principais fungos de sementes de trigo; Ilustrações dos principais fungos encontrados em sementes de trigo.

Identificação dos principais fungos das sementes de trigo.

Procedimento para identificação dos fungos das sementes de trigo; Descrição diagnostica dos principais fungos das sementes de trigo; Sclerotium Tode; Rhizoctonia DC; Chaetomium Kunze; Pleospora Rabenh; Sporobolomyces Kluy. & Niel; Rhodotorula Harrison; Phoma Sacc.; Septoria tritici Rob; Stagonospora nodorum (Berk.) Cas. & Germ.; Stagonospora avenae (Frank) Bisset f. sp. triticae; Colletotrichum graminicola (Ces.) Wilson; Fusarium tricinctum (Corda) Sacc; Fusarium moniliforme Sheldon; Fusarium avenaceum (Fr.) Sacc; Fusarium acuminatum Ell. & Kellerm; Fusarium equiseti (Corda) Sacc.; Fusarium graminearum Schw.; Mucor Micheli; Rhizopus Ehrenb; Aspergillus Link.; Penicillium Link.; Alternaria Nees; Epicoccum Link; Cladosporium Link; Nigrospora Zimm; Curvularia Boedijn; Drechslera tritici-repentis (Died.) Drech; Bipolaris sorokiniana (Sacc. in Sorok.) Shoem; Chave sistemática dos principais fungos de sementes de trigo; Ilustrações dos principais fungos encontrados em sementes de trigo.

Characterization of the complex locus of bean encoding polygalacturonase-inhibiting proteins reveals subfunctionalization for defense against fungi and insects.

Polygalacturonase-inhibiting proteins (PGIPs) are extracellular plant inhibitors of fungal endopolygalacturonases (PGs) that belong to the superfamily of Leu-rich repeat proteins. We have characterized the full complement of pgip genes in the bean (Phaseolus vulgaris) genotype BAT93. This comprises four clustered members that span a 50-kb region and, based on their similarity, form two pairs (Pvpgip1/Pvpgip2 and Pvpgip3/Pvpgip4). Characterization of the encoded products revealed both partial redundancy and subfunctionalization against fungal-derived PGs. Notably, the pair PvPGIP3/PvPGIP4 also inhibited PGs of two mirid bugs (Lygus rugulipennis and Adelphocoris lineolatus). Characterization of Pvpgip genes of Pinto bean showed variations limited to single synonymous substitutions or small deletions. A three-amino acid deletion encompassing a residue previously identified as crucial for recognition of PG of Fusarium moniliforme was responsible for the inability of BAT93 PvPGIP2 to inhibit this enzyme. Consistent with the large variations observed in the promoter sequences, reverse transcription-PCR expression analysis revealed that the different family members differentially respond to elicitors, wounding, and salicylic acid. We conclude that both biochemical and regulatory redundancy and subfunctionalization of pgip genes are important for the adaptation of plants to pathogenic fungi and phytophagous insects.

Influence of macro- and micronutrient fertilization on fungal contamination and fumonisin production in corn grains

The aim of this study was to investigate the effects of nutrients (nitrogen, zinc and boron) on fungal growth and fumonisins production in corn samples obtained at the beginning of grain formation and at harvest. Three nitrogen doses were applied to the corn plants through soil in combination with three zinc doses and two boron doses during sowing. Mycological analysis of grains, using Dichloran Rose-Bengal Chloramphenicol Agar, collected at the beginning of formation demonstrated a fungal population predominantly of yeasts. Analysis of freshly harvested corn revealed a higher frequency of Penicillium spp. (72%) and F verticillioides (27%). High Performance Liquid Chromatography analysis revealed that 100% of grains were contaminated with fumonisins B, at levels ranging from 0.3 to 24.3 mg/kg and 93% contaminated with fumonisin B(2) at levels ranging from 0.05 to 5.42 mg/kg. Nitrogen (50 kg/ha) in combination with boron (0.5 kg/ha) resulted in an increased fumonisin B2 production. (c) 2007 Elsevier Ltd. All rights reserved.

Effects of gamma-radiation on the fungus Alternaria alternata in artificially inoculated cereal samples

The objective of this study was to evaluate the effects of different gamma-radiation doses on the growth of Alternaria alternata in artificially inoculated cereal samples. Seeds and grains were divided into four groups: Control Group (not irradiated), and Groups 1, 2 and 3, inoculated with an A. alternata spore suspension (1 x 10(6) spores/mL) and exposed to 2, 5 and 10 kGy, respectively. Serial dilutions of the samples were prepared and seeded on DRBC (dichloran rose bengal chloramphenicol agar) and DCMA (dichloran chloramphenicol malt extract agar) media, after which the number of colony-forming units per gram was determined in each group. In addition, fungal morphology after irradiation was analyzed by scanning electron microscopy (SEM). The results showed that ionizing radiation at a dose of 5 kGy was effective in reducing the growth of A. alternata. However, a dose of 10 kGy was necessary to inhibit fungal growth completely. SEM made it possible to visualize structural alterations induced by the different gamma-radiation doses used. (C) 2009 Elsevier Ltd. All rights reserved.

Acute toxicity of a single gavage dose of fumonisin B(1) in rabbits

The aim of this study was to determine the clinical, pathological and mycotoxicological effects of oral administration of fumonisin B, (FBI) in rabbits. Eighteen rabbits were randomly assigned to two experimental groups: control group, 0 mg FB(1): fumonisin group. 31.5 mg FB(1)/kg body weight, corresponding to about 630 mg FB(1)/kg diet. Fumonisin administered as a single oral dose to rabbits resulted in acute toxicity, significantly interfering with body and liver weight. Serum biochemical analysis revealed a significant increase of total protein, alkaline phosphatase (AP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (GGT), urea and creatinine in the group receiving FBI compared to control animals, a finding characterizing hepatic and renal injury in this group. Urinary protein concentrations were markedly elevated at 12,24,48 and 72 h after dosing, although visible pathological abnormalities were not observed, probably because of rapid repair of the damage. FBI was detected in feces, with a maximum concentration at 24h after administration, indicating that the enterohepatic circulation is important in rabbits. FBI concentrations found in urine were low, with peak elimination at 12 h after intoxication. The highest FBI concentrations were observed in feces compared to urine and liver, demonstrating that feces are the main routes of excretion. (C) 2009 Elsevier Ireland Ltd. All rights reserved.

Fungos de pré e pós colheita e a qualidade de grãos de milho

O papel do milho na alimentação humana e animal é importante por causa da composição química e do valor nutritivo; por isso, é um dos cereais mais cultivados e consumidos no mundo. Uma das principais causas de danos à qualidade dos grãos é a infecção fúngica e a conseqüente contaminação por micotoxinas. Neste trabalho, foi identificado os efeitos do retardamento da colheita, do grau de umidade e do período de armazenamento dos grãos na ocorrência de fungos patogênicos e de grãos ardidos e a possível contaminação por micotoxinas na lavoura e durante o armazenamento, com o objetivo de caracterizar a influência dos fungos de pré e pós colheita na qualidade dos grãos de milho nas safras 98/99 e 99/00. A incidência de fungos patogênicos foi quantificada em 400 grãos e de grãos ardidos (GA), a percentagem de grãos com injúria mecânica visível (IMV) e de grãos normais (GN) em quatro repetições de 250 g de grãos. A contaminação por micotoxinas foi analisada por cromatografia de camada delgada e as características nutricionais foram analisadas por espectrometria de reflectância no infravermelho proximal. O retardamento da colheita gerou condições favoráveis para a elevação da incidência dos fungos das espécies Aspergillus spp., Cephalosporium spp., Fusarium graminearum e Penicillium spp. A incidência de GA se elevou enquanto os grãos apresentavam umidade acima de 20%. A incidência de Fusarium moniliforme foi reduzindo à medida que os grãos perdiam água. O percentual de grãos com IMV somados a incidência GA foi de 15,90% no silo de Lodi e de 15,78% na Cotrel. O retardamento de colheita influenciou na ocorrência de fungos, de GA e de micotoxinas na lavoura. As práticas de manejo das lavouras e a operação de colheita afetaram qualidade comercial dos grãos de milho e o armazenamento conservou as características nutricionais.

Relação entre características morfológicas da cariopse e fusariose em milho

Fusarium moniliforme causa sérios prejuízos no rendimento do milho. Suspeita-se que a entrada do fungo na cariopse ocorra pela cicatriz do estilete, e que este fato e o nível de infestação por F. moniliforme estejam relacionados com características morfológicas da cariopse. O objetivo deste trabalho foi identificar características morfológicas que conferem resistência a F. moniliforme em cariopses de milho. Cariopses de seis linhagens de milho, com e sem inoculação do patógeno, foram avaliadas utilizando-se de estereomicroscópio e o microscópio eletrônico de varredura. Características morfológicas da cariopse, tais como: tegumento com saliências e reentrâncias acentuadas, pericarpo pouco espesso, amido menos compacto e presença do canal estilar favorecem a penetração de F. moniliforme.

Effect of the type of environmental stress on the emergence of sunflower (Helianthus annus L.), soybean (Glycine max (L.) Merril) and maize (Zea mays L.) seeds with different levels of vigor

Sowing is a critical time in the cycle of a crop and the seeds are frequently exposed to adverse conditions that may compromise the establishment of seedlings in the field. on this basis, the objective of the present study was to determine the effect of types of environmental stress on the emergence of sunflower, maize and soybean seeds with different levels of vigor. High vigor seeds were artificially aged in order to obtain medium and low vigor seeds and then they were sown in clay soil in plastic boxes and submitted to the following types of environmental stress during the germination process : 1) high temperature (35degreesC), 2) low temperature (15 or 18degreesC), 3) water excess (Psi > -0.0001 MPa), 4) water deficiency (Psi approximately equal to -1.1; -1.2 and -0.6 MPa for sunflower, maize and soybean, respectively), 5) sowing at a depth of 7 cm and 6) pathogenic infection of sunflower seeds with Alternaria helianthi, of maize seeds with Fusarium moniliforme and of soybean seeds with Colletotrichum dematium, var. truncata. The results were compared to those obtained with controls sown under optimal condition. It was concluded that: 1) the effect of seed vigor on emergence depends on the type of enviromental stress to which the seeds are exposed, 2) the stress to which the the seeds demonstrated highest sensitivity varied with species and 3) high temperature stress was the one that most impaired the emergence of the three species.

Interaction between toxigenic fungi and weevils in corn grain samples

This study investigated the ability of weevils to transmit Aspergillus flavus and Fusarium verticillioides fungal spores and the consequent production of mycotoxins. For this purpose, corn grain samples were stored in flasks connected to a hose to form a closed system (flasks A and B). Flasks A were inoculated with the following groups: group 1 (corn + weevil); group 2 (corn + A. flavus); group 3 (corn + A. flavus + weevil); group 4 (corn + F. verticillioides); group 5 (corn + E verticillioides + weevil), and group 6 (corn + A. flavus + E verticillioides + weevil). Flasks B contained sterile grains. The samples were incubated for 10, 20 and 30 days, posteriorly, weight, water activity, mycoflora, aflatoxins and fumonisins. The corn grain samples were also submitted to scanning electron microscopy. Our results showed that weevils could enhance corn grains contamination by these fungi, hence, could increase mycotoxins production. These findings demonstrate the importance of weevils as fungal vectors and the need for good manipulation and storage practices of grains. (C) 2012 Elsevier Ltd. All rights reserved.