Cultivo in vitro de embriones aislados a partir de semillas de frutos inmaduros de irupé (Victoria cruziana, Nymphaeaceae)

The irupé or water corn (Victoria cruziana A. D. Orb.) belongs to the Nymphaeaceae family and arouses interest mainly due to the beauty of its leaves and flowers. Obtaining seeds of this aquatic species in its natural environment is challenging, and it is also considered a recalcitrant species for in vitro culture. For this reason, the aim of this work was to establish a methodology for the conversion into plants of irupé embryos extracted from seeds of immature fruits and to obtain material to be used in micropropagation or in environmental restoration programs. Embryo culture of fruits in six growth stages was carried out up to a maximum of four weeks. Using Murashige & Skoog’s basal medium, twelve culture media with and without the addition of growth regulators (gibberellic acid, AG3 and thidiazuron, TDZ) were tested. Embryos converted into plants in all media diluted to 50% (½ MS) with 3% sucrose, while plants with developed roots were obtained in the medium with the addition of 10 mg/L of GA3 . Although the culture of embryos derived from seeds in early fruit stages did not allow plant regeneration, this was possible when explants derived from fruits in late developmental stages.El irupé o maíz de agua (Victoria cruziana A. D. Orb.) pertenece a la familia Nymphaeaceae y despierta interés, principalmente, por la belleza de sus hojas y flores. La obtención de semillas de esta especie acuática es dificultosa en su ambiente natural y además es considerada recalcitrante para el cultivo in vitro. Por este motivo, el objetivo de este trabajo fue el establecimiento de una metodología para la conversión a plantas de embriones de irupé extraídos de semillas de frutos inmaduros y la obtención de material para ser empleado en la micropropagación o en programas de restauración ambiental. Se realizó el cultivo de embriones de frutos con seis estadios de crecimiento, hasta un máximo de cuatro semanas. Empleando el medio basal de Murashige & Skoog, se probaron doce medios de cultivo con y sin el agregado de reguladores de crecimiento (ácido giberélico, AG3 y thidiazuron, TDZ). Los embriones se convirtieron en plantas en todos los medios diluidos al 50% (½ MS), manteniendo el 3% de sacarosa, mientras que en el medio adicionado con 10 mg/L de AG3 se obtuvieron plantas con raíces desarrolladas. Si bien el cultivo de embriones derivados de las semillas en los estadios tempranos del fruto no permitió la regeneración de plantas, esta fue posible cuando los explantes derivaron de frutos en estadios tardíos

nifH pyrosequencing reveals the potential for location-specific soil chemistry to influence N2 -fixing community dynamics.

A dataset of 87 020 nifH reads and 16 782 unique nifH protein sequences obtained over 2 years from four locations across a gradient of agricultural soil types in Argentina were analysed to provide a detailed and comprehensive picture of the diversity, abundance and responses of the N2 -fixing community in relation to differences in soil chemistry and agricultural practices. Phylogenetic analysis revealed an expected high proportion of Alphaproteobacteria, Betaproteobacteria and Deltaproteobacteria, mainly relatives to Bradyrhizobium and Methylosinus/Methylocystis, but a surprising paucity of Gammaproteobacteria. Analysis of variance and stepwise regression modelling suggested location and treatment-specific influences of soil type on diazotrophic community composition and organic carbon concentrations on nifH diversity. nifH gene abundance, determined by quantitative real-time polymerase chain reaction, was higher in agricultural soils than in non-agricultural soils, and was influenced by soil chemistry under intensive crop rotation but not under monoculture. At some locations, sustainable increased crop yields might be possible through the management of soil chemistry to improve the abundance and diversity of N2 -fixing bacteria

Diversidad de helechos y licofitas del Parque Nacional Lago Puelo (Chubut-Argentina) Diversity of ferns and licophytes of the National Park Lago Puelo (Chubut- Argentina)

Se estudiaron los helechos y licofitas presentes en el Parque Nacional Lago Puelo, Chubut, Argentina. Se determinó la presencia de 47 taxa, de los cuales 12 constituyen nuevos registros para la Provincia de Chubut y 1 para la Región Patagónica. Se observó una elevada diversidad taxonómica, representando más del 50 % de la flora patagónica. Varios de los taxa crecen exclusivamente en el área y en Chile a iguales latitudes. El paso Puelo, que conecta Argentina y Chile, es el más bajo de la Cordillera de los Andes en Norpatagonia y es vía de ingreso de especies valdivianas. La presencia de animales de pastoreo, invasión de plantas exóticas y el riesgo latente de incendios, significan un peligro para la supervivencia de la flora del Parque. Todas estas características hacen que estas áreas de los Bosques Subantárticos merezcan una especial atención para su conservación. Se presentan claves para la determinación de los taxa y un mapa de ubicación de las áreas de mayor diversidad de helechos y licofitas dentro del parque. Para cada taxón registrado se da la distribución geográfica y datos ecológicos en el área de estudio.The ferns and licophytes from the National Park Lago Puelo, Chubut, Argentina were studied. We registered 47 taxa with 12 of them new records for the province of Chubut and 1new to Patagonia. A high taxonom-ic diversity was observed, with about 50 % of the Patagonian fern flora represented. Some of the taxa are growing exclusively in this area and in Chile at the same latitudes. The Puelo pass, which is connect-ing Argentina and Chile, at the lowest altitude of the North- Patagonian Andes, constituted a penetrating route of Valdivian species. The presence of pasture livestock, the invasion of exotic plants and the latent fires, are the principals dangers for the survival of the Flora in this area. Therefore these areas of the Subantartic Forest merit special attention for conservation. A taxonomic key is included and a distribu-tion map that shows the areas of highest diversity of ferns and lycophytes within the national park is given. For each taxon the geographical distribution and ecology data are also given

Induction of gibberellin 20-oxidases and repression of gibberellin 2β-oxidases in unfertilized ovaries of entire tomato mutant, leads to accumulation of active gibberellins and parthenocarpic fruit formation

In tomato (Solanum lycopersicum L.), auxin and gibberellins (GAs) cross-talk plays an important role during fruit-set. The entire tomato mutant has been previously reported to carry a deletion in the coding region of the SlIAA9 gene, a member of the auxin signal repressor family Aux/IAA. In this paper, we examined the role of ENTIRE gene in controlling GAs metabolism and directing spontaneous fruit initiation and early ovary growth. It was shown that, similarly to pollinated fruits, facultative parthenocarpy in entire depends on active GA metabolism, since fruit growth is suppressed when GA biosynthesis is blocked. Analysis of endogenous GAs during the first 10 days after flower emasculation revealed that entire fruits accumulated higher amounts of active GAs (GA1 and GA3) in comparison to wild type pollinated fruits, suggesting that a different GA homeostasis regulation occurs. Transcript analysis of the main GA biosynthesis genes showed that differently from unpollinated and non parthenocarpic wild type ovaries, in entire active GA flux modulation is regulated by the activation of SlGA20ox1 and SlGA20ox2 and also by a marked reduction of GA catabolism (reduced transcription of GA 2β-oxidase genes) during the early fruit expansion phase.Fil: Mignolli, Francesco. 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: Vidoz, María Laura. 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; Argentina. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias; ArgentinaFil: Mariotti, Lorenzo. Università degli Studi di Pisa; ItaliaFil: Lombardi, Lara. Università degli Studi di Pisa; ItaliaFil: Picciarelli, Piero. Università degli Studi di Pisa; Itali