GuaB Activity Is Required in Rhizobium tropici During the Early Stages of Nodulation of Determinate Nodules but Is Dispensable for the Sinorhizobium meliloti–Alfalfa Symbiotic Interaction

The guaB mutant strain Rhizobium tropici CIAT8999-10T is defective in symbiosis with common bean, forming nodules that lack rhizobial content. In order to investigate the timing of the guaB requirement during the nodule formation on the host common bean by the strain CIAT899-10.T, we constructed gene fusions in which the guaB gene is expressed under the control of the symbiotic promoters nodA, bacA, and nifH. Our data indicated that the guaB is required from the early stages of nodulation because full recovery of the wild-type phenotype was accomplished by the nodA-guaB fusion. In addition, we have constructed a guaB mutant derived from Sinorhizobium meliloti 1021, and shown that, unlike R. tropici, the guaB S. meliloti mutant is auxotrophic for guanine and induces wild-type nodules on alfalfa and Medicago truncatula. The guaB R. tropici mutant also is defective in its symbiosis with Macroptilium atropurpureum and Vigna unguiculata but normal with Leucaena leucocephala. These results show that the requirement of the rhizobial guaB for symbiosis is found to be associated with host plants that form determinate type of nodules.Fil: Collavino, Mónica Mariana. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botánica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botánica del Nordeste; ArgentinaFil: Riccillo, Pablo M.. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Grasso, Daniel Horacio. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Crespi, Martín. Centre National de la Recherche Scientifique; FranciaFil: Aguilar, Orlando Mario. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; Argentin

La actividad peroxidasa en caña de azúcar (Saccharum spp): evolución temporal de la reacción y su posible rol en la resistencia a la roya marrón (Puccinia melanocephala, H&P

La roya marrón de la caña de azúcar, causada por Puccinia melanocephala, es una enfermedad foliar de preocupación en casi todos los países donde se cultiva la caña de azúcar. Los programas de mejoramiento del cultivo se encuentran en la búsqueda de fuentes de resistencia de la planta al patógeno

GuaB activity is required in Rhizobium tropici during the early stages of nodulation of determinate nodules but is dispensable for the sinorhizobium meliloti-alfalfa symbiotic interaction

The guaB mutant strain Rhizobium tropici CIAT8999-10T is defective in symbiosis with common bean, forming nodules that lack rhizobial content. In order to investigate the timing of the guaB requirement during the nodule formation on the host common bean by the strain CIAT899-10.T, we constructed gene fusions in which the guaB gene is expressed under the control of the symbiotic promoters nodA, bacA, and nifH. Our data indicated that the guaB is required from the early stages of nodulation because full recovery of the wild-type phenotype was accomplished by the nodA-guaB fusion. In addition, we have constructed a guaB mutant derived from Sinorhizobium meliloti 1021, and shown that, unlike R. tropici, the guaB S. meliloti mutant is auxotrophic for guanine and induces wild-type nodules on alfalfa and Medicago truncatula. The guaB R. tropici mutant also is defective in its symbiosis with Macroptilium atropurpureum and Vigna unguiculata but normal with Leucaena leucocephala. These results show that the requirement of the rhizobial guaB for symbiosis is found to be associated with host plants that form determinate type of nodules.Instituto de Biotecnologia y Biologia Molecula

Analysis of nifH-RNA reveals phylotypes related to Geobacter and Cyanobacteria as important functional components of the N₂-fixing community depending on depth and agricultural use of soil

In this survey, a total of 80 787 reads and 28 171 unique NifH protein sequences were retrieved from soil RNA. This dataset extends our knowledge about the structure and diversity of the functional diazotrophic communities in agricultural soils from Argentinean Pampas. Operational taxonomic unit (OTU)-based analyses showed that nifH phylotypes related to Geobacter and Anaeromyxobacter (44.8%), Rhizobiales (29%), Cyanobacteria (16.7%), and Verrucomicrobiales (8%) are key microbial components of N2 fixation in soils associated with no-till management and soil depth. In addition, quantification of nifH gene copies related to Geobacter and Cyanobacteria revealed that these groups are abundant in soils under maize–soybean rotation and soybean monoculture, respectively. The correlation of physicochemical soil parameters with the diazotrophic diversity and composition showed that soil stability and organic carbon might contribute to the functional signatures of particular nifH phylotypes in fields under no-till management. Because crop production relies on soil-borne microorganism's activities, such as free N2 fixation, the information provided by our study on the diazotrophic population dynamics, associated with the edaphic properties and land-use practices, represents a major contribution to gain insight into soil biology, in which functionally active components are identified.Instituto de Biotecnologia y Biologia Molecula

The impact of COVID-19 pandemic on pornography habits: a global analysis of Google Trends

As the COVID-19 spread globally, social distancing, self-isolation/quarantine, and national lockdowns have become crucial to control the pandemic. However, these measures may also lead to increases in social isolation, loneliness, and stress, which can alter the consumption of pornography habits. The aim of the study was thus to explore the interest pattern in pornography and coronavirus-themed pornography during the COVID-19 outbreak. Google Trends\uae was employed to determine the most popular porn websites (Porn, XNXX, PornHub, xVideos, and xHamster), and coronavirus-themed pornography worldwide and in six nations with different COVID-19 outbreak and self-isolation recommendations. We analyzed every search trend on Google\uae from January 9, 2020 to May 25, 2020 using \u201cjoint point regression analysis\u201d. Comparisons of week relative search volume (WRSV) and temporal patterns were analyzed to assess the change of interest in search terms during nations lockdowns. Paired t-test was used to compare WRSV values among the porn websites during the national lockdowns and the equivalent timespan of the weeks in the previous 4 years. The research trend of almost every keyword increased with significant inflection points for those nations with a straight \u201cstay at home orders\u201d (China, Italy, Spain, and France). \u201cPornHub\u201d and \u201cPorn\u201d showed the highest increase of interest worldwide with an average weekend percentage change (AWPC) of 4.9 and 3.8, respectively. The mean WRSV for keywords in USA and Sweden did not show a similar increase as the other nations. The WRSV percentage change with the historical data had a peak during the straight nations\u2019 lockdowns (p < 0.01). All the nations had a significant increase in WRSV coronavirus-themed pornography for each keyword (p < 0.01) with an AWPC, ranging worldwide between 18.5 and 61.8 (p < 0.01), after the beginning of self-quarantine. As strengths this study uses a big data technology to collect worldwide trend of interest, however, data are anonymous and do not allow analysis of subpopulation groups. In conclusion, we demonstrated an increased interest in pornography and coronavirus-themed pornography after the outbreak of COVID-19 in nations with a straight \u201cstay at home orders\u201d

Avances en la investigación de la relación patogeno-hospedante y de la resistencia genética a enfermedades de la caña de azúcar en Argentina

Esta contribución presenta avances en la investigación de la variabilidad y resistencia genética con relación a “Roya marrón” y “Estría roja” de la caña de azúcar en Argentina. Resultados experimentales de la inoculación con roya en condiciones controladas permitieron postular que tanto la actividad peroxidasa basal como la tasa de su crecimiento con posterioridad a la infección serían mecanismos complementarios que favorecen la expresión de la resistencia a la enfermedad. También se investigó la diversidad molecular en poblaciones de roya con base en 538 marcadores AFLP a partir de muestreos en diferentes variedades y en una amplia faja de distribución de la enfermedad en el NOA. No se detectaron estructuras genéticas diferenciadas según orígenes, comportándose las diferentes poblaciones como una única gran población indiferenciada de uredosporos con alto grado de variabilidad genética intrínseca. Con relación a Estría roja se logró optimizar una técnica efectiva para el aislamiento, identificación y caracterización genética del agente responsable de la enfermedad. Los resultados obtenidos permitieron confirmar que Acidovorax avenae es el agente responsable de estría roja de la caña de azúcar en Argentina, siendo ésta la primera caracterización realizada en la región cañera para esta patología. Por otra parte el análisis de perfiles de REP-PCR y RAPD confirmó la presencia de al menos cuatro biotipos de la enfermedad en aislados de Salta y Tucumán. La existencia de diversidad genética entre aislamientos permite diseñar estrategias de control mediante el uso de variedades resistentes.The paper presents recent progress in the investigation of variability and genetic resistance in relation to Rust and Red stripe diseases of sugar cane in Argentina. Experimental results for rust innoculation under controlled conditions served to postulate that both basal peroxidase activity and its rate of increase after innoculation with the disease could be complementary mechanisms in the expression of resistance in different cultivars. Molecular diversity of rust populations collected in the field in North West Argentina were also investigated based on 538 AFLP markers. Samples collected in different varieties and sites indicated that rust uredospores populations correspond with a single mixed undifferentiated population with a high degree of intrinsic genetic variability. In regard to Red stripe it was possible to optimize an effective procedure for the isolation, identification and genetic characterization of the disease agent. Results permitted for the first time the identification of Acidovorax avenae as the agent responsible for the disease in Argentina. The profile analysis for REP-PC and RAPD indicated the presence of at least four different biotypes of the disease in Salta and Tucumán. The occurrence of genetic diversity among isolates permits the design of strategies for the control of the disease by means of resistant varieties.Fil: Mariotti, Jorge Alberto. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Machado Assefh, Cristina Renata. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; ArgentinaFil: Rech, G.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Fontana, P. D.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Collavino, N. G.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Pocoví, M. I.. Universidad Nacional de Salta. Facultad de Ciencias Naturales; ArgentinaFil: Rago, A. M.. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Daz, Mirta Elizabeth. Universidad Nacional de Salta. Facultad de Ciencias Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta; Argentin

Influencia de Cassava common mosaic virus (CSCMV) en la producción de raíces de plantas de Manihot esculenta

La mandioca, uno de los principales cultivos para consumo humano y animal, posee gran importancia económica-social en muchos países. Su multiplicación comercial es agámica, por lo que una de sus limitantes es la diseminación de patógenos sistémicos, principalmente virus, a través del material de propagación.En Latinoamérica, el CsCMV es uno de los más distribuidos y, en la región productora (nordeste argentino), se registraron incidencias crecientes durante los años 2014 a 2016, asociadas con síntomas graves de mosaico de hojas, provocando el Mosaico común de la mandioca. El objetivo fue evaluar el efecto de la infección con CsCMV sobre componentes del rendimiento de plantas de mandioca. Para ello, se utilizaron 30 estacas que provenían de plantas de un ciclo, regeneradas in vitro a partir de cultivo de meristemas caulinares de plantas con CsCMV del cultivarCM3306-4 y de plantas sanas que oficiaron de control. El ensayo se instaló con un diseño completamente aleatorizado, en mulching plástico y riego por goteo, en el Campo Experimental del Instituto Universitario de la Universidad Nacional de Formosa.La cosecha se realizó manualmente luego de ocho meses desde plantación (2018). El análisis estadístico fue realizado mediante comparación de medias aritméticas por T-Test (P < 0,05), con el programa InfoStat. Existieron diferencias significativas entre componentes de rendimiento, excepto para altura de planta. El daño potencial fue: 44% (peso total de raíces); 38% (peso fresco aéreo); 28% y 43% (número de ramas totales y ramas útiles, respectivamente); 28% (número de raíces totales); 21% y 10% (longitud y diámetro promedio de raíces por planta). Estos resultadosremarcan la importancia del virus en cultivos de mandioca del NEA y la necesidad de erradicar la enfermedad de los lotes de cultivo