Pyrenophora tritici repentis, the causal agent of tan spot: a review of intraspecific genetic diversity

In some countries where the wheat is cultivated, the biological adversities are led by foliar disease. These diseases have emerged as a serious problem in many areas where the wheat is the principal crop. In the last few years, minimum tillage has been considered advantageous to soil conservation, but it leads to a loss of available nutrients and a potential increase in necrotic pathogens whose saprophytic stage lives in the straw of the crop (Annone, 1985). Establishment of the crop under this management can be affected by pathogens of this type. Leaf spotting diseases can be caused by one or a combination of leaf spotting pathogens (Table 1). Leaf spotting diseases affect wheat grown reduce the photosynthetic area of leaves resulting in reduced grain filling and lower yields; particularly when the top two leaves (penultimate and flag leaves) are severely infected. The most of these diseases are similar in host symptomatology, disease cycle, life cycles of pathogens and types of damage induced. Whitin of these pathogens the Ascomycota fungus, Pyrenophora tritici-repentis (Ptr) (Died.) Drechs. It is a facultative pathogen whose asexual stage is Drechslera tritici-repentis (Dtr) (Died.). This pathogen is the causal agent of tan spot of wheat

Caracterización cultural, patogénica y bioquímica de Pyrenophora tritici-repentis en la Argentina

Tesis presentada para optar al Grado de Doctor en Ciencias NaturalesFil: Moreno, María Virginia. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin

Respuesta del trigo (Triticum spp.) y la cebada (Hordeum vulgare) a Fusarium poae.

La fusariosis de la espiga es una enfermedad importante que ataca al trigo (Triticumspp.), la cebada (Hordeum vulgare) y otros granos en el mundo. Entre las especies deFusariumque causan esta enfermedad,Fusarium poaees una de las menos frecuentes, pero es un hongo cuya importancia es cada vez más reconocida y se le asocia con la toxicosis en humanos y animales. El objetivo de este estudio fue examinar las respuestas de las variedades de trigo y cebada a la inoculación de diferentes aislamientos deF. poae, a fin de observar la contaminación producida por este hongo en los granos. Los análisis se realizaron durante 2008, 2009 y 2010 en condiciones naturales, en la Facultad de Agronomía de Azul-UNCPBA, provincia de Buenos Aires, Argentina. Se hicieron análisis estadísticos, y las identidades de los aislamientos re-aislados se probaron con reacciones de iniciadores específicos PCR y por comparación de amplificaciones de ADN-ISSR. Las diferencias entre variedades en los síntomas del hongo fueron significativas (p≤0.05) sólo en 2008. Aunque el número de aislamientos re-aislados en trigo fue mayor que el número de muestras con síntomas observables, las correlaciones no fueron significativas. Sin embargo, hubo correlaciones significativas en la cebada y los análisis de regresión lineal sugiriendo que por cada grano con síntomas visibles, dos granos de cebada podrían contener el hongo. Asi puede concluirse que el número de granos contaminados conF. poaees significativamente mayor que el de aquellos con síntomas observables de la enfermedad y, por tanto, el alcance real de la contaminación conF. poaees subestimado y se debiera considerar para el análisis de riesgos alimentarios en un futuro próximo.Fusariumhead blight is an important disease attacking wheat (Triticumspp.), barley (Hordeum vulgare) and other grains worldwide. Among theFusariumspecies causing this disease,Fusarium poaeis less often implicated, but is a fungus of increasingly recognized importance and it is associated with human and animal toxicoses. The aim of this study was to examine the responses of wheat and barley varieties to inoculation by differentF. poaeisolates, in order to observe contamination by this fungus in the grains. The analyses were performed during 2008, 2009, and 2010 under natural conditions at the Facultad de Agronomía de Azul-UNCPBA, province of Buenos Aires, Argentina. Statistical analyses were carried out and the identities of re-isolated isolates were tested by a primer-specific PCR reaction and by comparing DNA-ISSR amplifications. Differences among varieties in fungal symptoms were significant (p≤0.05) only in 2008. Although the number of re-isolated isolates in wheat was greater than the number of samples with observable symptoms, no significant correlations were found. However, there were correlations in barley and the linear regression analyses allow suggesting that for each grain with visual symptoms, two barley grains could contain the fungus. Thus it can be concluded that the real number of grains contaminated withF. poaeis significantly higher than the number with observable disease symptoms, and therefore the real extent of contamination withF. poaeis currently underestimated and should be considered for food risk analysis in the near future

The Impact of Activity Design in Internet Plagiarism in Higher Education = El impacto del diseño de actividades en el plagio de Internet en educación superior

In this work we aim to gain a better understanding of the nature of plagiarism in Higher Education. We analyse a set of different activities in an online university-level course, aiming to understand which tasks lead more naturally to plagiarism. This analysis concludes that the activities that have a lower rate of plagiarism are activities that encourage involvement, originality and creativity. Subsequently, we reformulate the task that presented the highest rate of plagiarism, taking into account the conclusions of the previous analysis and trying to maintain their relative effort and educational impact. We then compare the newly designed activities with their original counterparts to measure whether there is a significant reduction in plagiarism. The results are clear and show a significant drop in the percentages of plagiarism. In addition, we performed an additional validation to ensure that both groups were, in fact comparable. We found that both groups displayed similar plagiarism attitudes in other exercises that were not reformulated. This study shows that it is possible to reduce the incidence of plagiarism by designing activities in such a way that prompts students to propose their own ideas using information available on the Internet as a vehicle for their solutions rather than as solutions in themselves

El impacto del diseño de actividades en el plagio de Internet en educación superior

El objetivo de este trabajo es comprender mejor la naturaleza del plagio en la Educación Superior. Analizamos una serie de actividades en un curso on-line de nivel universitario, con el objetivo de encontrar qué tareas llevan más naturalmente al plagio. Este análisis concluye que las actividades que tienen una menor tasa de plagio son actividades que fomentan la participación, la originalidad y la creatividad. Posteriormente, reformulamos la tarea que presenta la mayor tasa de plagio, teniendo en cuenta las conclusiones del análisis anterior y tratando de mantener su esfuerzo relativo y el impacto educativo. A continuación, comparamos las actividades del nuevo diseño con las originales para medir si el rediseño conlleva una reducción significativa del plagio. Los resultados son claros y muestran una caída significativa en los porcentajes de plagio. Además, se realizó una validación adicional en la que se analizó la actividad con la segunda tasa de plagio más alta, encontrando que los grupos eran comparables y mostraban actitudes de plagio similares en otros ejercicios que no habían sido rediseñados. Este estudio muestra que es posible reducir la incidencia de plagio mediante el diseño de actividades de tal manera que los estudiantes se sientan motivados para proponer sus propias ideas utilizando la información disponible en Internet como vehículo para sus soluciones en lugar de como soluciones en sí mismasIn this work we aim to gain a better understanding of the nature of plagiarism in Higher Education. We analyse a set of different activities in an online university-level course, aiming to understand which tasks lead more naturally to plagiarism. This analysis concludes that the activities that have a lower rate of plagiarism are activities that encourage involvement, originality and creativity. Subsequently, we reformulate the task that presented the highest rate of plagiarism, taking into account the conclusions of the previous analysis and trying to maintain their relative effort and educational impact. We then compare the newly designed activities with their original counterparts to measure whether there is a significant reduction in plagiarism. The results are clear and show a significant drop in the percentages of plagiarism. In addition, we performed an additional validation to ensure that both groups were, in fact, comparable. We found that both groups displayed similar plagiarism attitudes in other exercises that were not reformulated. This study shows that it is possible to reduce the incidence of plagiarism by designing activities in such a way that prompts students to propose their own ideas using information available on the Internet as a vehicle for their solutions rather than as solutions in themselve

Neotropical Seasonally Dry Forests: Response of Soil Fungal Communities to Anthropogenic Actions

The aim of this review was to analyze the information available on soil fungal community of Neotropical Seasonally dry forests, with special attention given to the Chaco area. This review is focused on the loss of soil fungal community due to anthropogenic actions such as forest clearing. Over the last decades, the expansion of the agricultural frontier has had a wide range of physical, chemical and biological effects on Neotropical dry forests. As these changes on the Schinopsis dry forests (Chaco) have rendered the ecosystem vulnerable, these areas have become some of the few protected areas in South America. After analyzing both national and international studies to find the latest research available on the topic we have noticed there is lack of specific studies on soil fungal community in the Chaco area, unlike Cerrado and Caatinga where most studies have been carried out. Therefore, we propose to conduct more in-depth studies on soil fungi in Schinopsis forests to revalue the Chaco fungal community to use them as potential indicators of soil health and to develop new management techniques.Instituto de Botánica "Dr. Carlos Spegazzini

Neotropical Seasonally Dry Forests: Response of Soil Fungal Communities to Anthropogenic Actions

The aim of this review was to analyze the information available on soil fungal community of Neotropical Seasonally dry forests, with special attention given to the Chaco area. This review is focused on the loss of soil fungal community due to anthropogenic actions such as forest clearing. Over the last decades, the expansion of the agricultural frontier has had a wide range of physical, chemical and biological effects on Neotropical dry forests. As these changes on the Schinopsis dry forests (Chaco) have rendered the ecosystem vulnerable, these areas have become some of the few protected areas in South America. After analyzing both national and international studies to find the latest research available on the topic we have noticed there is lack of specific studies on soil fungal community in the Chaco area, unlike Cerrado and Caatinga where most studies have been carried out. Therefore, we propose to conduct more in-depth studies on soil fungi in Schinopsis forests to revalue the Chaco fungal community to use them as potential indicators of soil health and to develop new management techniques.Instituto de Botánica "Dr. Carlos Spegazzini

Mapping QTL for resistance against <i>Pyrenophora tritici-repentis</i> in wheat

Tan spot, caused by the fungus Pyrenophora tritici-repentis (Died.) Drechs is an important foliar disease of wheat (Triticum aestivum L.). From a set of phenotypically and molecularly characterized set of Argentinean isolates, two isolates H0019 and H0120 which do not correspond to known races of the pathogen were selected. Segregation for resistance among a set of recombinant inbred lines bred from the cross 'W7984' × cv. 'Opata 85' was used to identify the basis for resistance at the seedling stage, against those fungal isolates (H0019 and H0120), across three independent environments. On the basis of the mean performance across all three environments, a QTL against chlorosis located on the 6AS and linked to the RFLP locus Xksuh4c was significant for both isolates (with a LOD of 3.76 for isolate H0019 and 5.87 for H0120).Facultad de Ciencias Agrarias y Forestale

Mapping QTL for resistance against <i>Pyrenophora tritici-repentis</i> in wheat

Tan spot, caused by the fungus Pyrenophora tritici-repentis (Died.) Drechs is an important foliar disease of wheat (Triticum aestivum L.). From a set of phenotypically and molecularly characterized set of Argentinean isolates, two isolates H0019 and H0120 which do not correspond to known races of the pathogen were selected. Segregation for resistance among a set of recombinant inbred lines bred from the cross 'W7984' × cv. 'Opata 85' was used to identify the basis for resistance at the seedling stage, against those fungal isolates (H0019 and H0120), across three independent environments. On the basis of the mean performance across all three environments, a QTL against chlorosis located on the 6AS and linked to the RFLP locus Xksuh4c was significant for both isolates (with a LOD of 3.76 for isolate H0019 and 5.87 for H0120).Facultad de Ciencias Agrarias y Forestale

Respuesta del Trigo (triticum spp.) y la Cebada (hordeo vulgare) a Fusarium poae

Fusarium head blight is an important disease attacking wheat (Triticum spp.), barley (Hordeum vulgare) and other grains worldwide. Among the Fusarium species causing this disease, Fusarium poae is less often implicated, but is a fungus of increasingly recognized importance and it is associated with human and animal toxicoses. The aim of this study was to examine the responses of wheat and barley varieties to inoculation by different F. poae isolates, in order to observe contamination by this fungus in the grains. The analyses were performed during 2008, 2009, and 2010 under natural conditions at the Facultad de Agronomía de Azul-UNCPBA, province of Buenos Aires, Argentina. Statistical analyses were carried out and the identities of re-isolated isolates were tested by a primer-specific PCR reaction and by comparing DNAISSR amplifications. Differences among varieties in fungal symptoms were significant (p£0.05) only in 2008. Although the number of re-isolated isolates in wheat was greater than the number of samples with observable symptoms, no significant correlations were found. However, there were correlations in barley and the linear regression analyses allow suggesting that for each grain with visual symptoms, two barley grains could contain the fungus. Thus it can be concluded that the real number of grains contaminated with F. poae is significantly higher than the number with observable disease symptoms, and therefore the real extent of contamination with F. poae is currently underestimated and should be considered for food risk analysis in the near future.La fusariosis de la espiga es una enfermedad importante que ataca al trigo (Triticum spp.), la cebada (Hordeum vulgare) y otros granos en el mundo. Entre las especies de Fusarium que causan esta enfermedad, Fusarium poae es una de las menos frecuentes, pero es un hongo cuya importancia es cada vez más reconocida y se le asocia con la toxicosis en humanos y animales. El objetivo de este estudio fue examinar las respuestas de las variedades de trigo y cebada a la inoculación de diferentes aislamientos de F. poae, a fin de observar la contaminación producida por este hongo en los granos. Los aná- lisis se realizaron durante 2008, 2009 y 2010 en condiciones naturales, en la Facultad de Agronomía de Azul-UNCPBA, provincia de Buenos Aires, Argentina. Se hicieron análisis estadísticos, y las identidades de los aislamientos re-aislados se probaron con reacciones de iniciadores específicos PCR y por comparación de amplificaciones de ADN-ISSR. Las diferencias entre variedades en los síntomas del hongo fueron significativas (p£0.05) sólo en 2008. Aunque el número de aislamientos re-aislados en trigo fue mayor que el número de muestras con síntomas observables, las correlaciones no fueron significativas. Sin embargo, hubo correlaciones significativas en la cebada y los análisis de regresión lineal sugiriendo que por cada grano con síntomas visibles, dos granos de cebada podrían contener el hongo. Asi puede concluirse que el número de granos contaminados con F. poae es significativamente mayor que el de aquellos con síntomas observables de la enfermedad y, por tanto, el alcance real de la contaminación con F. poae es subestimado y se debiera considerar para el análisis de riesgos alimentarios en un futuro próximoFil: Stenglein, Sebastian Alberto. Facultad de Agronomía de Azul; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Dinolfo, María Inés. Facultad de Agronomía de Azul; ArgentinaFil: Bongiorno, Fabricio. Facultad de Agronomía de Azul; ArgentinaFil: Moreno, Maria Virginia. Facultad de Agronomía de Azul; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin