Aislamiento, identificación y control biológico de especies de Alternaria aisladas de trigo

El trigo (Triticum aestivum) es afectado por enfermedades ocasionadas por hongos, virus y/o procariotas, algunos de los cuales están ampliamente difundidos limitando los rendimientos y la calidad de los mismos. Entre las enfermedades fúngicas que afectan al cultivo, se destaca la roya (Puccinia spp), mancha amarilla (Dreschlera tritici-repentis) y golpe blanco (Fusarium graminearum); y otras emergentes, como las producidas por especies del género Alternaria; siendo las más prevalentes A. alternata, A. tenuissima, A. infectoria y A. arborescens en Argentina. Pueden causar lesiones en hoja del tipo “tizón” causando mermas en el rendimiento y en el grano, como el punto o escudete negro. El manejo de enfermedades foliares se realiza históricamente a través de la resistencia genética y el control químico; sin embargo, es importante contar con herramientas alternativas, siendo el control biológico una opción complementaria de manejo integrado. Los objetivos del trabajo fueron: 1- aislar especies de Alternaria a partir de muestras de hoja con síntomas de tizón; 2- evaluar el efecto de un biocontrolador sobre las especies de Alternaria identificadas a nivel de laboratorio y en invernadero. El aislamiento de las especies de Alternaria se realizó en medio selectivo pentacloronitrobenceno a partir de hojas con síntomas de tizón provenientes de Marcos Juárez, Córdoba. A partir de los aislamientos se realizaron cultivos monospóricos y se sembraron en los medios Agar V8 y Agar papa-zanahoria para su identificación por metodología clásica. Se aislaron e identificaron un total de 11 cepas de Alternaria, siendo las especies encontradas A. alternata y A. infectoria. Se evaluó la interacción in vitro con la cepa biocontroladora, Bacillus velezensis RC218 (Bv218). La capacidad antagonista de Bv218 se comprobó en cultivos duales en placa conteniendo Agar papa glucosado utilizando la técnica de Índice de Dominancia. La interacción en laboratorio entre las especies de Alternaria y Bv218 se evaluó inoculando el hongo en la zona central de la placa y estrías de la bacteria a 3 cm de distancia, se incubó por 5 días a 25 ºC en oscuridad, observándose una dominancia a distancia por parte de la cepa biocontroladora. A nivel de espiga de trigo, se estudió bajo invernadero la capacidad colonizadora de las especies de Alternaria; y, de manera conjunta, se comparó el efecto con la aplicación preventiva de Bv218 sobre las especies de Alternaria. Los microorganismos se aplicaron en el período de antesis mediante aspersión y se cubrieron con una bolsa de nylon por 3 días; luego se retiraron las bolsas y se evaluó la capacidad colonizadora a los 12 días. Las especies evaluadas de Alternaria colonizaron las espigas de trigo bajo las condiciones ensayadas, observándose un micelio blanco-grisáceo, de mayor densidad y abundancia en las cepas de A. alternata en comparación con A. infectoria. En los tratamientos con Bv218 se observó menor colonización de las espigas por las especies de Alternaria. Las espigas evaluadas en los diferentes tratamientos sólo se clasificaron de manera cualitativa dado que no se evidenció daño de tipo necrótico en las mismas. Todos los grupos de especies de Alternaria estudiados contienen representantes patógenos que producen diversas alteraciones tanto en semilla como en hoja de las plantas de trigo. La utilización de estrategias de control con agentes de bajo impacto ambiental, como bacterias biocontroladoras, presentó resultados prometedores para su aplicación. El efecto antagonista de B. velezensis RC218 fue demostrado bajo condiciones de laboratorio.Fil: Contreras, J.. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigación en Micología y Micotoxicología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación en Micología y Micotoxicología; ArgentinaFil: Oddino, Claudio Marcelo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigación en Micología y Micotoxicología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación en Micología y Micotoxicología; ArgentinaFil: Palazzini, Juan Manuel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigación en Micología y Micotoxicología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación en Micología y Micotoxicología; ArgentinaIV Reunión Conjunta de Sociedades de Biología de la República Argentina: Nuevas Evidencias y Cambios de Paradigmas en Ciencias BiológicasMendozaArgentinaSociedad Argentina de BiologíaSociedad de Biología de RosarioSociedad Chilena de Reproducción y DesarrolloSociedad de Biología de CórdobaSociedad de Biología de CuyoAsociación de Biología de Tucumá

Correlation between Fusarium graminearum and deoxynivalenol during the 2012/13 wheat Fusarium head blight outbreak in Argentina

Fusarium graminearum (Schwabe) is reported as the main causal agent of Fusarium head blight in Argentina. The disease causes great losses in humid and semi-humid regions of the world, reducing grain yield and quality. During 2012/13 harvest season, a severe epidemic occurred in Argentina. The aims of this work were to determine the F. graminearum incidence and deoxynivalenol accumulation in wheat grain and flour samples obtained from two of the main wheat growing regions from Argentina. Levels of the pathogen and deoxynivalenol content were correlated in heads, grains and flour. Out of 69 wheat grain samples, 55 (79.7%) showed deoxynivalenol levels between 0.4 and 8.5 μg/kg. Fusarium graminearum was the main species isolated, the isolation frequency ranged from 30 to 52% of the total grains analyzed. Correlations were observed between deoxynivalenol content, % of F. graminearum infection, presence of the pathogen in heads, grain and flour

Incomplete echocardiographic recovery at 6\ua0months predicts long-term sequelae after intermediate-risk pulmonary embolism. A post-hoc analysis of the Pulmonary Embolism Thrombolysis (PEITHO) trial

Introduction: Symptoms and functional limitation are frequently reported by survivors of acute pulmonary embolism (PE). However, current guidelines provide no specific recommendations on which patients should be followed after acute PE, when follow-up should be performed, and which tests it should include. Definition and classification of late PE sequelae are evolving, and their predictors remain to be determined. Methods: In a post hoc analysis of the Pulmonary Embolism Thrombolysis (PEITHO) trial, we focused on 219 survivors of acute intermediate-risk PE with clinical and echocardiographic follow-up 6 months after randomisation as well as over the long term (median, 3 years after acute PE). The primary outcome was a composite of (1) confirmed chronic thromboembolic pulmonary hypertension (CTEPH) or (2) \u2018post-PE impairment\u2019 (PPEI), defined by echocardiographic findings indicating an intermediate or high probability of pulmonary hypertension along with New York Heart Association functional class II\u2013IV. Results: Confirmed CTEPH or PPEI occurred in 29 (13.2%) patients, (6 with CTEPH and 23 with PPEI). A history of chronic heart failure at baseline and incomplete or absent recovery of echocardiographic parameters at 6 months predicted CTEPH or PPEI at long-term follow-up. Conclusions: CTEPH or PPEI occurs in almost one out of seven patients after acute intermediate-risk PE. Six-month echocardiographic follow-up may be useful for timely detection of late sequelae

Comparison of ddRADseq and EUChip60K SNP genotyping systems for population genetics and genomic selection in Eucalyptus dunnii (Maiden)

Eucalyptus dunnii is one of the most important Eucalyptus species for short-fiber pulp production in regions where other species of the genus are affected by poor soil and climatic conditions. In this context, E. dunnii holds promise as a resource to address and adapt to the challenges of climate change. Despite its rapid growth and favorable wood properties for solid wood products, the advancement of its improvement remains in its early stages. In this work, we evaluated the performance of two single nucleotide polymorphism, (SNP), genotyping methods for population genetics analysis and Genomic Selection in E. dunnii. Double digest restriction-site associated DNA sequencing (ddRADseq) was compared with the EUChip60K array in 308 individuals from a provenance-progeny trial. The compared SNP set included 8,011 and 19,008 informative SNPs distributed along the 11 chromosomes, respectively. Although the two datasets differed in the percentage of missing data, genome coverage, minor allele frequency and estimated genetic diversity parameters, they revealed a similar genetic structure, showing two subpopulations with little differentiation between them, and low linkage disequilibrium. GS analyses were performed for eleven traits using Genomic Best Linear Unbiased Prediction (GBLUP) and a conventional pedigree-based model (ABLUP). Regardless of the SNP dataset, the predictive ability (PA) of GBLUP was better than that of ABLUP for six traits (Cellulose content, Total and Ethanolic extractives, Total and Klason lignin content and Syringyl and Guaiacyl lignin monomer ratio). When contrasting the SNP datasets used to estimate PAs, the GBLUP-EUChip60K model gave higher and significant PA values for six traits, meanwhile, the values estimated using ddRADseq gave higher values for three other traits. The PAs correlated positively with narrow sense heritabilities, with the highest correlations shown by the ABLUP and GBLUP-EUChip60K. The two genotyping methods, ddRADseq and EUChip60K, are generally comparable for population genetics and genomic prediction, demonstrating the utility of the former when subjected to rigorous SNP filtering. The results of this study provide a basis for future whole-genome studies using ddRADseq in non-model forest species for which SNP arrays have not yet been developed

Assessment of Physical-Chemical Drinking Water Quality in the Logone Valley (Chad-Cameroon)

Unsafe drinking water is one of the main concerns in developing countries. In order to deal with this problem, a cooperation project was set up by the ACRA Foundation in the Logone valley (Chad-Cameroon). Water supplies were sampled throughout the villages of this area mostly from boreholes, open wells, rivers and lakes as well as some piped waters. The samples were analysed for their physical-chemical and microbiological quality in order to identify the contamination problems and suggest appropriate solutions. Results of the assessment confirmed that in the studied area there are several parameters of health and aesthetic concern. Elevated lead levels were detected both in aquifers and in surface waters, confirming that further investigations of the occurrence of lead contamination in the Logone valley are warranted. In addition, many groundwater sources are negatively impacted by parameters of aesthetic concern, such as turbidity, iron and manganese. Even though they do not affect human health, elevated levels of these parameters cause consumers to abandon improved water supplies, often in favour of surface water sources that are microbiologically contaminated. The use of alternative sources, improvement of water supply structures and water treatment are possible solutions to improve the quality of drinking water in the Logone valle

INTERNATIONAL UNIVERSITY COOPERATION FOR VALORIZING CRUDE EARTH AS BUILDING MATERIAL IN CHAD AND CAMEROON

Deforestation is one of the most dramatic threats to environmental equilibrium and food safety in many regions of the world, and particularly in sub-Saharan Africa. It is enhanced by many kinds of human activities, among which is the earth brick firing process, that needs large amounts of wood for attaining and maintaining temperatures required during this process. Crude earthen bricks can be used as an alternative for buildings, with environmental benefits; however, the economical and social sustainability of this building technique is linked to the improvement of the brick production technology, based on a deeper knowledge of the local resources. For this reason, a partnership was developed between an Italian University and a Cameroonian one for valorizing crude earth as building material in the Logone valley, located at the border between Chad and Cameroon: this way, the knowledge of the local context owned by the Cameroonian university was an added value to the technical skills of both universities, driving the choices made during the project. The Cameroonian university carried out mainly morphological and geotechnical analyses on soils, in order to choose the best site for brick production in the region; the Italian university designed and followed the realization of a machine for improving brick production. As a result, a pilot plant for crude earth brick production was installed

Bacillus velezensis RC 218 as a biocontrol agent to reduce Fusarium head blight and deoxynivalenol accumulation: Genome sequencing and secondary metabolite cluster profiles

Bacillus subtilis RC 218 was originally isolated from wheat anthers as a potential antagonist of Fusarium graminearum, the causal agent of Fusarium head blight (FHB). It was demonstrated to have antagonist activity against the plant pathogen under in vitro and greenhouse assays. The current study extends characterizing B. subtilis RC 218 with a field study and genome sequencing. The field study demonstrated that B. subtilis RC 218 could reduce disease severity and the associated mycotoxin (deoxynivalenol) accumulation, under field conditions. The genome sequencing allowed us to accurately determine the taxonomy of the strain using a phylogenomic approach, which places it in the Bacillus velezensis clade. In addition, the draft genome allowed us to use bioinformatics to mine the genome for potential metabolites. The genome mining allowed us to identify 9 active secondary metabolites conserved by all B. velezensis strains and one additional secondary metabolite, the lantibiotic ericin, which is unique to this strain. This study represents the first confirmed production of ericin by a B. velezensis strain. The genome also allowed us to do a comparative genomics with its closest relatives and compare the secondary metabolite production of the publically available B. velezensis genomes. The results showed that the diversity in secondary metabolites of strains in the B. velezensis clade is driven by strains making different antibacterials.Fil: Palazzini, Juan Manuel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología. Cátedra de Micología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Dunlap, Christopher A.. United States Department of Agriculture; Estados UnidosFil: Bowman, Michael J.. United States Department of Agriculture; Estados UnidosFil: Chulze, Sofia Noemi. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología. Cátedra de Micología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin