First report of Phoma sorghina (Sacc.) Boerema Dorenbosch & van Kest on wheat leaves (Triticum aestivum L.) in Argentina

A new disease caused by Phoma sorghina has been detected for the first time on wheat plants in the Province of Buenos Aires, Argentina. The pathogen was isolated from wheat leaves growing under field conditions, cultured on PDA and identified by its morphobiometric and cultural characters. The disease symptoms and morphological characters of the pathogen are described. Pathogenicity of the isolate was confirmed by inoculating 10 wheat cultivars under greenhouse conditions.Centro de Investigaciones en Fitopatologí

Occurrence of Ascochyta hordei var. europaea on wheat (Triticum aestivum) leaves in Argentina

During the course of a 2002 survey in the wheat cropping area of Buenos Aires Province, Argentina, an unusual disease was found on wheat leaves. From the symptomatic tissues, a fungus was isolated and identified as Ascochyta hordei var. europaea. To test its pathogenicity and fulfill Koch’s postulates, inoculations under greenhouse conditions were carried out. The symptoms of the disease and the causal agent are described.Centro de Investigaciones en Fitopatologí

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

The endophytic fungi from wheat (<i>Triticum aestivum</i> L.)

In order to study the species composition of endophytes from wheat healthy plants in Buenos Aires Province (Argentina) and to determine their infection frequencies from leaves, stems, glumes and grains, wheat plants were collected from five cultivars at five growth stages from crop emergence to harvest. A total of 1,750 plant segments (leaves, stems, glumes and grains) were processed from the five wheat cultivars at five growth stages, and 722 isolates of endophytic fungi recovered were identified as 30 fungal genera. Alternaria alternata, Cladosporium herbarum, Epicoccum nigrum, Cryptococcus sp., Rhodotorula rubra, Penicillium sp. and Fusarium graminearum were the fungi that showed the highest colonization frequency (CF%) in all the tissues and organs analysed. The number of taxa isolated was greater in the leaves than those in the other organs analysed.Facultad de Ciencias Agrarias y ForestalesCentro de Investigaciones en Fitopatologí

Isolation and analysis of endophytic microorganisms in wheat (<i>Triticum aestivum</i> L.) leaves

The present investigation was undertaken in order to select the surface-sterilization technique most efficient for eliminating epiphytes, to document the spectrum of endophytes of healthy leaves from three wheat cultivars in Buenos Aires Province (Argentina) and to determine their infection frequencies at three growth stages. Surface-sterilization with undiluted commercial solution of sodium hypochlorite was reaffirmed as adequate for removing epiphytes on wheat leaves. From the 450 wheat leaf segments incubated, three bacterial isolates and 130 fungal isolates were obtained. From all the isolates, 19 fungal species were identified. Bacterial isolates were characterized as Bacillus sp. There were significant differences between microorganisms, stages of growth, and stages × microorganisms interaction. Differences between cultivars, stages × cultivars, microorganisms × cultivars and for the triple interaction were not significant. Frequency of microorganisms isolated increased with crop age, but it was statistically similar for the three wheat cultivars tested (Klein Centauro, Klein Dragon and Buck Ombu). Rhodotorula rubra, Alternaria alternata, Cladosporium herbarum and Epicoccum nigrum were isolated in the highest frequency. The other microorganisms were present at intermediate or low values. The species isolated may be assigned to three groups: (a) well-known and economically important pathogens of wheat, (b) commonly abundant phylloplane fungi considered to be primary saprobic and minor pathogens and (c) species occasionally present in wheat.Facultad de Ciencias Agrarias y ForestalesCentro de Investigaciones en Fitopatologí

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