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Doubled haploid ramets via embryogenesis of haploid tissue cultures

Tissue culture in the oil palm business is generally concerned with the multiplication (clonal production) of dura, pisifera and tenera palms. These are all normal diploids (2n=2x=36). Sumatra Bioscience has pioneered haploid tissue culture of oil palm (n=x=18). Haploid oil palm is the first step in producing doubled haploid palms which in turn provide parental lines for F1 hybrid production. Chromosome doubling is known to occur during embryogenesis in other haploid cultures, e.g. barley anther culture. Haploid tissue cultures in oil palm were therefore set up to investigate and exploit spontaneous chromosome doubling during embryogenesis. Flow cytometry of embryogenic tissue showed the presence of both haploid (n) and doubled haploid (2n) cells indicating spontaneous doubling. Completely doubled haploid ramets were regenerated suggesting that doubling occurred during the first mitoses of embryogenesis. This is the first report of doubled haploid production in oil palm via haploid tissue culture. The method provides a means of producing a range of doubled haploids in oil palm from the 1,000 plus haploids available at Sumatra Bioscience, in addition the method also produced doubled haploid (and haploid) clones. 1

Buoyant magnetic flux ropes in a magnetized stellar envelope: Idealized numerical 2.5-D MHD simulations

Context: The context of this paper is buoyant toroidal magnetic flux ropes, which is a part of flux tube dynamo theory and the framework of solar-like magnetic activity. Aims: The aim is to investigate how twisted magnetic flux ropes interact with a simple magnetized stellar model envelope--a magnetic "convection zone"--especially to examine how the twisted magnetic field component of a flux rope interacts with a poloidal magnetic field in the convection zone. Method: Both the flux ropes and the atmosphere are modelled as idealized 2.5-dimensional concepts using high resolution numerical magneto-hydrodynamic (MHD) simulations. Results: It is illustrated that twisted toroidal magnetic flux ropes can interact with a poloidal magnetic field in the atmosphere to cause a change in both the buoyant rise dynamics and the flux rope's geometrical shape. The details of these changes depend primarily on the polarity and strength of the atmospheric field relative to the field strength of the flux rope. It is suggested that the effects could be verified observationally.Comment: 8 pages, 5 figures (9 files), accepted by A&

A coupled model of magnetic flux generation and transport in stars

We present a combined model for magnetic field generation and transport in cool stars with outer convection zones. The mean toroidal magnetic field, which is generated by a cyclic thin-layer alpha-omega dynamo at the bottom of the convection zone is taken to determine the emergence probability of magnetic flux tubes in the photosphere. Following the nonlinear rise of the unstable thin flux tubes, emergence latitudes and tilt angles of bipolar magnetic regions are determined. These quantities are put into a surface flux transport model, which simulates the surface evolution of magnetic flux under the effects of large-scale flows and turbulent diffusion. First results are discussed for the case of the Sun and for more rapidly rotating solar-type stars.Comment: Astron. Nachr. /AN, 328, 1111-1113 (2007). A newer, more extended paper related to this study can be reached here: http://arxiv.org/abs/1102.0569 (A&A 528, A135 [2011]). The supplementary animations can be reached here: http://www.aip.de/AN/movie

Magnetic flux generation and transport in cool stars

The Sun and other cool stars harbouring outer convection zones manifest magnetic activity in their atmospheres. The connection between this activity and the properties of a deep-seated dynamo generating the magnetic flux is not well understood. By employing physical models, we study the spatial and temporal characteristics of the observable surface field for various stellar parameters. We combine models for magnetic flux generation, buoyancy instability, and transport, which encompass the entire convection zone. The model components are: (1) a thin-layer alpha-Omega dynamo at the base of the convection zone; (2) buoyancy instabilities and the rise of flux tubes through the convection zone in 3D, which provides a physically consistent determination of emergence latitudes and tilt angles; and (3) horizontal flux transport at the surface. For solar-type stars and rotation periods longer than about 10 days, the latitudinal dynamo waves generated by the deep-seated alpha-Omega dynamo are faithfully reflected by the surface distribution of magnetic flux. For rotation periods of the order of two days, however, Coriolis acceleration of rising flux loops leads to surface flux emergence at much higher latitudes than the dynamo waves at the bottom of the convection zone reach. A similar result is found for a K0V star with a rotation period of two days. In the case of a rapidly rotating K1 subgiant, overlapping dynamo waves lead to noisy activity cycles and mixed-polarity fields at high latitudes.Comment: 14 pages, 14 figures. Accepted for publication in Astronomy & Astrophysic

Análisis de la expresión diferencial de genes involucrados en las vías metabólicas responsables de la síntesis de antocianinas en frutos de Fragaria chilensis ssp. chiloensis f. chiloensis y Fragaria chiloensis ssp. chilensis f. patagónica

133 p.El objetivo de la tesis doctoral fue realizar un estudio comparativo de la pigmentación de fruto dentro de las dos formas botánicas de Fragaria chiloensis ssp. chiloensis. El estudio fue abordado a nivel transcripcional y químico. Para ello, frutos de ambas formas botánicas, f. chiloensis (frutilla nativa blanca) y f. patagonica (frutilla nativa roja), fueron recolectados en cuatro distintos estadios de desarrollo y maduración (verde pequeño, verde grande, blanco y maduro). A partir de fruto completo, sus órganos constituyentes (receptáculo y aquenio) y tejidos, se analizaron los perfiles transcripcionales de genes estructurales y regulatorios (factores de transcripción) involucrados en las vías de biosíntesis de compuestos fenilpropanoides responsables de la formación de antocianinas a lo largo de los diferentes estadios. Mediante este exhaustivo análisis transcripcional, se seleccionó uno de los genes regulatorios, FcMYB1, debido a su expresión diferencial detectada entre receptáculo de fruto rojo y blanco. El ortólogo de este gen aislado en frutilla comercial demostró ser un supresor de la acumulación de pigmentos antociánicos en el sistema heterólogo de Nicotiana. Para caracterizar su función de manera homóloga en Fragaria chiloensis ssp. chiloensis f. chiloensis, frutos de frutilla blanca en estadio verde grande fueron agroinyectados con una cepa de A. tumefaciens portadora de una construcción de RNAi para FcMYB1 y cosechados en estadio maduro. Este trabajo demostró que la supresión génica del factor de transcripción FcMYB1 propició la aparición de un fenotipo de frutos más pigmentados que los frutos control agroinyectados con vector vacío. Consecuentemente, los genes flavonoides finales relacionados con la biosíntesis de proantocianidinas mostraron niveles muy bajos de transcritos de leucoantocianidina reductasa (LAR) y antocianidina reductasa (ANR) en contraste con los niveles aumentados de transcritos de genes directamente relacionados con la biosíntesis de pigmentos antociánicos, antocianidina sintasa (ANS) y UDP-glicosiltransfersa (UFGT). Esta redirección a nivel transcripcional de la vía flavonoides coincidió con una mayor acumulación de antocianinas en frutos agroinyectados con la construcción RNAi-FcMYB1 detectadas por HPLC-DAD. En conclusión, por medio del estudio comparativo en frutos contrastantes en pigmentación de una misma especie de frutilla, se detectaron diferencias en los niveles de transcritos de genes estructurales y regulatorios. Tras este análisis se seleccionó un factor de transcripción que demostró ser importante en la producción de pigmentos en esta especie. Los genes diferencialmente expresados (estructurales y/o regulatorios) identificados en esta investigación pueden ser empleados como marcadores moleculares para asistir los programas de mejoramiento genético de frutilla./ABSTRACT: The aim of this doctoral thesis was to perform a comparative study of the fruit pigmentation of two botanical forms of Fragaria chiloensis ssp. chiloensis. The study was carried out at the transcriptional and chemical level. For this purpose, fruits of both botanical forms, f. chiloensis (white native strawberry) and f. patagonica (red native strawberry), were collected and sorted in four distinct developmental and ripening stages (small green, large green, white and ripe). From whole fruit, their constituent organs (receptacle and achene) and tissues, the transcriptional profiles of structural and regulatory (transcription factors) genes involved in anthocyanin related biosynthesis pathways were assessed among the different stages. By means of this exhaustive transcriptional analysis, FcMYB1, a regulatoty gene was selected due to its differential expression detected between the receptacle of red and white fruits. Its orthologous gene isolated from the commercial strawberry demonstrated it to be a suppressor of the anthocyanin pigment as shown by accumulation in the heterologous system Nicotiana. For characterizing its function in a homologue manner in Fragaria chiloensis ssp. chiloensis f. chiloensis, fruits of white strawberry at large green stage were agroinjected with an A. tumefaciens strain bearing a RNAi construct for FcMYB1 and collected at ripe stage. According to this work, the gene suppression of this FT FcMYB1 favored a more pigmented phenotype in these fruits than in control fruits agroinjected with empty vector. Consequently, the final flavonoid genes related with proanthocyanidin biosynthesis showed very low levels of leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR) in contrast to the elevated transcript levels of genes closely related to anthocyanic pigment biosynthesis, anthocyanidin synthase (ANS) y UDP-glycosyltransferse (UFGT). This flavonoid pathway redirection at the transcriptional level coincided with a greater accumulation of anthocyanin in RNAi-FcMYB1 agroinjected fruits assessed by HPLC-DAD. In conclusion, through this comparative study carried out in fruits with contrasting pigmentation in the same strawberry species, differences in transcript levels of structural and regulatory genes were detected. After this analysis, a transcription factor that proved to be important in the pigment production in this specie was selected. Differentially expressed (structural and/or regulatory) genes identified in this research could be used as molecular markers for assisting strawberry breeding programs

Evaluación de caracteres agronómicos en un programa de mejoramiento genético de arándanos (Vaccinium corymbosum L.)

52 p.En el marco de un creciente aumento en el mercado mundial y nacional de arándanos durante los últimos años y de la necesidad de contar con variedades adaptadas a nuestras zonas productivas, se justifica el programa de mejoramiento genético de arándanos de arbusto alto (highbush) que la empresa Genberries Ltda. desarrolla en Chile y del cual este estudio forma parte. Con el objetivo de seleccionar material con mejores características de calidad de fruta en cosecha y postcosecha, se estudió la fenología y caracteres de calidad de fruta de 79 genotipos, los que se encuentran divididos en 6 subgrupos con distinto número de representantes en cada uno: Rosados, Estrés, Avanzadas, Cosecha Tardía, Buena Postcosecha y Promisorias, los que el programa había seleccionado y agrupado previamente. El estudio se realizó en la Estación Experimental Panguilemo, de propiedad de la Universidad de Talca, ubicada en km 245, Ruta 5 Sur, Talca, Región del Maule, Chile (35° 22’ 15,3’’ Sur; 71° 35’ 43,6’’ Oeste). Se estudió el momento de ocurrencia, en días calendario a partir del 1 de enero de 2013, de 15 etapas fenológicas de crecimiento reproductivo, adaptadas de la tabla de estados de crecimiento de arándanos (Blueberry Growth Stages; Michigan State University, 2012), y ello se comparó con tres variedades comerciales de arándano de arbusto alto (highbush): Duke, Brigitta y Elliott, consideradas variedades de cosecha temprana, media estación y tardía, respectivamente. Además se evaluaron cinco caracteres de calidad de fruta: peso por fruto, firmeza, diámetro, sólidos solubles y pérdida de peso en frutos, tanto a cosecha como después de 60 días de almacenaje a 1°C, más dos días a temperatura ambiente (20-25°C). Los resultados muestran que frutos de los subgrupos Buena Postcosecha y Rosados, tenían mayor tamaño de frutos que los demás subgrupos. Además hacia el final de los 60 días (1°C), más dos días a temperatura ambiente (20-25°C) los subgrupos Cosecha Tardía y Buena Postcosecha obtuvieron los más altos niveles de firmeza, con 109,7 y 103,52 g/mm, respectivamente. No se observó grandes diferencias en el contenido de sólidos solubles entre los subgrupos, pero para todos los subgrupos hubo un aumento en su contenido conforme pasaron los días en almacenaje. En general, la pérdida de peso tuvo una tendencia lineal y se aceleró durante los días que la fruta estuvo a temperatura ambiente. También se encontró que existe una alta correlación entre el contenido de sólidos solubles y el diámetro de los frutos, que en general fue -0,55, significativa al p<0,001.Palabras clave: Arándano, mejoramiento genético, fenología, postcosecha, firmeza, sólidos solubles, pérdida de peso./ABSTRACT:In the light of an increasing demand over recent years in the world and national markets for blueberries and the need for varieties adapted to our production conditions, Genberries Ltda. developed a highbush blueberry breeding program in Chile, the material from which forms the basis for this study. With a view to selecting material with better fruit quality characteristics at harvest and postharvest, the phenology and fruit quality traits of 79 genotypes were studied. These 79 were divided into 6 subgroups with different numbers of representatives in each, namely: Rosados, Estrés, Avanzadas, Cosecha Tardía, Buena Postcosecha y Promisorias, which the program had previously selected and grouped. The study was conducted at the Panguilemo Estación Experimental, owned by the Universidad de Talca, located at km 245, Ruta 5 Sur, Talca, Región del Maule, Chile (35° 22' 15.3'' South, 71° 35' 43.6'' West). The timings of 15 phenological stages of reproductive growth were recorded as calendar days from January 1, 2013. The stages were, adapted from the Table of Blueberry Growth Stages (Michigan State University, 2012), and the observations were compared with three commercial varieties of high bush blueberry: Duke, Brigitta and Elliott, considered as early mid-season and late harvest varieties, respectively. Furthermore, five fruit quality traits were evaluated: fruit weight, firmness, diameter, soluble solids and weight loss in fruits, both at harvest and after 60 days of storage at 1 °C followed by two days at room temperature (20-25 °C). The results showed that fruit of Buena Postcosecha and Rosados subgroups, had fruit size greater than the other subgroups. Also at the end of 60 days (1°C), plus two days at room temperature (20-25°C), the subgroups Cosecha Tardía and Buena Postcosecha had the highest levels of firmness, at 109.7 and 103,5 g/mm, respectively. No major differences in the content of soluble solids between subgroups were detected, but for all subgroups there was an increase in soluble solids after time in storage. Overall, weight loss showed a linear trend, which accelerated during the days the fruit was at room temperature. Also, overall, a highly significant (p<0.001) negative correlation between soluble solids and fruit diameter was found.Key words: Blueberry, breeding, phenology, postharvest, firmness, soluble solids, weight los

Flow instabilities of magnetic flux tubes IV. Flux storage in the solar overshoot region

We consider the effects of material flows on the dynamics of toroidal magnetic flux tubes located close to the base of the solar convection zone, initially within the overshoot region. The problem is to find the physical conditions in which magnetic flux can be stored for periods comparable to the dynamo amplification time, which is of the order of a few years. We carry out nonlinear numerical simulations to investigate the stability and dynamics of thin flux tubes subject to perpendicular and longitudinal flows. We compare the simulations with the results of simplified analytical approximations. We determine ranges of the flow parameters for which a linearly Parker-stable magnetic flux tube is stored in the middle of the overshoot region for a period comparable to the dynamo amplification time. The residence time for magnetic flux tubes with fluxes of 2x10^{21} Mx in the convective overshoot layer is comparable to the dynamo amplification time, provided that the average speed and the duration of the downflow do not exceed about 50 m/s and 100 days, respectively, and that the lateral extension of the flow is smaller than about 10 degrees.Comment: Accepted to be published in Astronomy and Astrophysics. 16 pages, 16 figures. To access GIF animations, use http://www.mps.mpg.de/homes/ishik/flute/frict_inst.gif, http://www.mps.mpg.de/homes/ishik/flute/TF60.gif and http://www.mps.mpg.de/homes/ishik/flute/TF180.gi

In vitro propagation of cedar (Cedrela odorata L.) from juvenile shoots

Garriga, M (Garriga, Miguel); Caligari, PDS (Caligari, Peter D. S.). Univ Talca, Inst Biol Vegetal & Biotecnol, Talca, ChileCedrela odorata L. is one of the most important timber species currently traded in the Caribbean and Central America; however, it has been intensively exploited. In vitro techniques and clonal propagation can help to develop new plantations and assist in establishing improvement programs for this species. The aim of this study was to develop a protocol to establish in vitro conditions and to micropropagate this species from nodal explants from juvenile cuttings taken from field trees. Disinfection of node explants with 5% propiconazole CE 25 during 3 min resulted in 100% explant disinfection and 60% morphogenic response on those established explants. Shoot development was optimized by cultivating in vitro node explants in Murashige and Skoog basal medium supplemented with 2 mg L(-1) 6-bencilaminopurine and 3 mg L(-1) naphthaleneacetic acid. This medium resulted in 100% shoot development from the in vitro node explants with a 3.93 cm mean height. Rooting was also stimulated 6 wk after individualization of the regenerated plants on the same micropropagation medium with a mean of 3.9 roots per plant. In vitro plants did not show morphologic differences when compared to ex vitro seeds