Manual de Nematología agrícola: bases y procedimientos.

El objetivo del este manual de nematología agrícola, busca servir de herramienta a productores, técnicos, investigadores, profesores y alumnos, que puedan descubrir el maravilloso universo de los nematodos que habitan nuestros suelos agrícolas. Este manual proporciona las guías y protocolos básicos para el adecuado muestreo, procesamiento, extracción e identificación de nematodos de muestras de suelo y vegetal.CONACYT - Consejo Nacional de Ciencia y TecnologíaPROCIENCI

Enzymatic and Molecular Identification of Meloidogyne Species in Tomato Orchards in Paraguay

Tomato is a major crop in Paraguay, where it provides a source of employment and income for households. Tomato production can be affected by root-knot nematodes, especially Meloidogyne spp. The unequivocal identification of Meloidogyne spp. in Paraguay has not been conducted yet. This study aims to identify Meloidogyne species in eight tomato production districts of this country by biochemical and molecular techniques. Females of Meloidogyne spp. were extracted from tomato roots and characterized using esterase isozyme phenotypes. In addition, DNA was extracted from nematode eggs, and species-specific SCARs (sequence-characterized amplified regions) were used to confirm the diagnosis. Nematodes were detected in 100% of studied samples (prevalence), of which M. incognita (Est: I2, Rm: 1.1;1.2) and M. javanica (Est: J3, Rm: 1.0, 1.20, 1.35) were present in 39.13% and 26.08% of samples, respectively. One population (8.69%) of Meloidogyne sp. presenting an atypical esterase profile (Rm: 1.0 and 1.3) was only detected in Julián Augusto Saldívar District. Mixed populations, mostly M. incognita and M. javanica, were observed in 26.08% of samples. The SCAR primers incK14F/incK14R amplified specific fragments for M. incognita (399 bp) and M. javanica (670 bp), confirming the enzymatic results. Here, we present the first study of root-knot nematode identification at the species level in Paraguay

A Standard Greenhouse Method for Assessing Soybean Cyst Nematode Resistance in Soybean: SCE08 (Standardized Cyst Evaluation 2008)

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is distributed throughout the soybean [Glycine max (L.) Merr.] production areas of the United States and Canada (Fig. 1) (26). SCN remains the most economically important pathogen of soybean in North America; the most recent estimate of soybean yield reduction in North America due to SCN totaled 34,659,000 metric tons during 2006 (34)

Determination of soybean cultivar resistance to soybean cyst nematode with quantitative polymerase chain reaction

Heterodera glycines, the soybean cyst nematode, is the major pathogen of Glycine max (soybean). Effective management of this pathogen is contingent on the use of resistant cultivars, thus screening for resistant cultivars is essential. The purpose of this research was to develop a method to assess infection of soybean roots by H. glycines with real-time quantitative Polymerase Chain Reaction (qPCR), a prelude to differentiation of resistance levels in soybean cultivars. Two experiments were conducted. In the first one, a consistent inoculation method was developed using to provide active second-stage juveniles (J2). Two-day-old soybean roots were infested with 0 and 1000 J2/mL. Twenty-four hours after infestation, the roots were surface sterilized and DNA was extracted with the DNA FastKit (MP Biomedicals, Santa Ana, CA)). For the qPCR assay, primer pair for single copy gene HgSNO, which codes for a protein involved in the production of vitamin B6, was selected for H. glycines DNA amplification within soybean roots. In the second experiment, compatible Lee 74, incompatible Peking and cultivars with different levels of resistance to H. glycines were inoculated with 0 and 1,000 J2/seedlings. Twenty-four hours post inoculation they were transplanted into pasteurized soil. Subsequently they were harvested at 1, 7, 10, 14 and 21 days post inoculation for DNA extraction. With the qPCR assay, the time needed to differentiate highly resistant cultivars from the rest was reduced. Quantification of H. glycines infection by traditional means (numbers of females produced in 30 days) is a time-consuming practice; the qPCR method can replace the traditional one and improve precision in determining infection levels

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This is research on nematodes

Libro de resúmenes: Primera Conferencia Internacional de Fitopatologia

La fitopatología es la ciencia encargada de estudiar a estos patógenos, diagnosticar las enfermedades que estos causan y en dicho proceso generar tácticas de manejo integrado. Son los fitopatólogos los que investigan a estos organismos y sus interacciones con los cultivos. Estas investigaciones resultan en estrategias para lograr una producción sostenible de alimentos en un ecosistema saludable. Esta Primera Conferencia Internacional de Fitopatologia del Paraguay es uno de los tantos ejemplos donde un grupo de fitopatólogos con diferentes especialidades se reúne y decide organizar un evento para poder compartir el conocimiento acumulado en esta área. Lo hacen por un sentimiento de deber y compromiso y, asimismo, para dar el puntapié inicial con el fin de comenzar una tradición que los futuros fitopatólogos del Paraguay ahora deberán continuar.CONACYT - Consejo Nacional de Ciencias y TecnologíaPROCIENCI

1er Congreso de Horticultura: la agricultura del mañana

Paraguay registra un avance sostenible y sin descanso en los agronegocios Hoy el agronegocio constituye el sector central del desarrollo del país en cuanto a su diversidad, a la cantidad de personas y a las empresas involucradas de manera directa e indirecta. Las posibilidades productivas de alimentos y bienes agrarios alimenticios y no alimenticios del Paraguay son inmensas. A medida que la población de un país crece y se desarrolla, en esa misma medida crece la demanda no solo de los bienes alimenticios y no alimenticios provenientes del uno racional y sostenible de los recursos naturales, sino también de la necesidad de tierra para la producción.CONACYT - Consejo Nacional de Ciencias y TecnologíaPROCIENCI

Annotation of Protein Domains Reveals Remarkable Conservation in the Functional Make up of Proteomes Across Superkingdoms

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Giant Starship Elements Mobilize Accessory Genes in Fungal Genomes

Accessory genes are variably present among members of a species and are a reservoir of adaptive functions. In bacteria, differences in gene distributions among individuals largely result from mobile elements that acquire and disperse accessory genes as cargo. In contrast, the impact of cargo-carrying elements on eukaryotic evolution remains largely unknown. Here, we show that variation in genome content within multiple fungal species is facilitated by Starships, a newly discovered group of massive mobile elements that are 110 kb long on average, share conserved components, and carry diverse arrays of accessory genes. We identified hundreds of Starship-like regions across every major class of filamentous Ascomycetes, including 28 distinct Starships that range from 27 to 393 kb and last shared a common ancestor ca. 400 Ma. Using new long-read assemblies of the plant pathogen Macrophomina phaseolina, we characterize four additional Starships whose activities contribute to standing variation in genome structure and content. One of these elements, Voyager, inserts into 5S rDNA and contains a candidate virulence factor whose increasing copy number has contrasting associations with pathogenic and saprophytic growth, suggesting Voyager's activity underlies an ecological trade-off. We propose that Starships are eukaryotic analogs of bacterial integrative and conjugative elements based on parallels between their conserved components and may therefore represent the first dedicated agents of active gene transfer in eukaryotes. Our results suggest that Starships have shaped the content and structure of fungal genomes for millions of years and reveal a new concerted route for evolution throughout an entire eukaryotic phylum