Resumen Introducción. La transformación del arroz (Oryza sativa L. ssp indica) mediada por Agrobacterium, representa una oportunidad para la investigación científica y el mejoramiento genético. Es necesaria la optimización del protocolo para obtener la mayor eficiencia de transformación. Objetivo. Evaluar diferentes factores que afectan la transformación genética en callos embriogénicos de arroz de la subespecie indica vía Agrobacterium tumefaciens. Materiales y métodos. Este estudio se realizó en San José, Costa Rica, entre 2012 y 2014. En seis tratamientos se evaluaron: el efecto de la edad del callo, la concentración de acetosiringona, condición luminosa, la presencia o ausencia de radícula y la cepa de Agrobacterium tumefaciens en la transformación genética de callos embriogénicos de arroz de la variedad CR5272 con el gen reportero gus. Se compararon la cepa de Agrobacterium LBA4404 con el plásmido pCAMBIA1305.2 y las cepas ATHV, GV3101 y LBA4404, con el plásmido pCAMBIA1303; mediante pruebas histoquímicas para la detección de la expresión transitoria del gen marcador que codifica para la β-glucuronidasa. Resultados. La evaluación de los seis tratamientos con la cepa LBA4404::pCAMBIA1305.2 resultó en expresión transitoria del gen GusPlus de 1,33-7,00 % para la variedad CR5272 y de 8,00 % para el control con la variedad Nipponbare (ssp. japonica). Las cepas con el plásmido pCAMBIA1303 presentaron una expresión transitoria del gen gusA entre el 100-65 % con un área promedio de 14,23 mm2 (ATHV), 8,81 mm2 (GV3101), y 8,83 mm2 (LBA4404), sin diferencias significativas entre ellas; sin embargo, sí hubo diferencias al compararlas con la cepa LBA4404::pCAMBIA1305.2 (85 %, 4,39 mm2). Conclusiones. La utilización de las condiciones: callos de seis días, concentración de acetosiringona de 76 µM, luz antes y después del cocultivo, presencia de radícula y la cepa ATHV::pCAMBIA 1303, mejoraron la eficiencia de transformación con Agrobacterium tumefaciens en la variedad de arroz CR5272.

Abstract Introduction. Agrobacterium-mediated transformation of rice (Oryza sativa L. ssp indica) represents an opportunity for scientific research and genetic improvement. Optimization of the protocol is necessary to obtain the highest transformation efficiency. Objective. To evaluate different factors that affect the genetic transformation in embryogenic rice callus of subspecies indica through Agrobacterium tumefaciens. Materials and methods. This study was performed in San José, Costa Rica between 2012 and 2014. The following were evaluated in six treatments: the effect of callus age, acetosyringone concentration, lighting condition, the presence or absence of radicle, and Agrobacterium tumefaciens strain on the genetic transformation of embryogenic calli of rice variety CR5272 with gus reporter gene. Agrobacterium strains LBA4404 with pCAMBIA1305.2 plasmid, and strains ATHV, GV3101, and LBA4404 with the pCAMBIA 1303 plasmid were compared; by histochemical tests for the detection of transient expression of the β-glucuronidase reporter gene. Results. The evaluation of the six treatments with strain LBA4404::pCAMBIA 1305.2 resulted in transient expression of 1.33-7.00 % of the GusPlus gene for the CR5272 variety, and 8.00 % for the control with the Nipponbare (ssp. japonica) variety. The strains with the pCAMBIA1303 plasmid showed a transient expression of the gusA gene between 100-65 % with an average area of 14.23 mm2 (ATHV), 8.81 mm2 (GV3101), and 8.83 mm2 (LBA4404) with no significant differences between them; however, there were differences when compared with strain LBA4404::pCAMBIA1305.2 (85 %, 4.39 mm2). Conclusions. The use of the conditions: six-day callus, acetosyringone concentration of 76 µM, light before and after cocultivation, presence of radicle and the ATHV::pCAMBIA 1303 , improved the transformation efficiency with Agrobacterium tumefaciens in the rice variety CR5272.

Abstract The influence of silver nitrate (AgNO3), benzyladenine (BAP), and indole-3-acetic acid (IAA) on low frequency somatic embryogenesis (LFSE) induction in Caturra and Catuaí arabica coffee was evaluated. For the Caturra cultivar, the production of somatic embryos was significantly increased by adding AgNO3 to the semisolid culture medium. The highest average number of somatic embryos for this cultivar was obtained using 6.6 μM BAP, 2.85 μM IAA, and 40 μM AgNO3. In contrast, for the Catuaí cultivar, the highest average number of somatic embryos was obtained using semisolid medium supplemented with 8.8 μM BAP, and 2.85 μM IAA. Using these protocols, somatic embryos were directly induced using leaf sections of in vitro plants of both coffee cultivars within 8 weeks. The somatic embryos developed into rooted plants with a 100% survival rate upon transfer to the greenhouse.

La presente investigación tuvo como objetivo optimizar los parámetros que afectan la incorporación y expresión de genes marcadores mediante biobalística en segmentos de hoja y embriones somáticos de café (Coffea arabica. L. cvs. Caturra y Catuaí). La mayor expresión transitoria del gen uidA en segmentos de hoja de Caturra (18.3±2.8) y Catuaí (6.8±2.0) y embriones somáticos de Catuaí (80.0±7.4) se obtuvo al cultivar los explantes por cinco horas previo al bombardeo en el medio Yasuda complementado con 0.5M mannitol+0.5M sorbitol. Asimismo, se obtuvo una mayor expresión transitoria del gen uidA al bombardear los segmentos de hoja de Caturra y Catuaí y embriones somáticos de Catuaí con una presión de helio de 1 100psi y una distancia de bombardeo de 6 o 9 cm.

The aim of this work was to optimize the biolistic delivery parameters that affect the DNA delivery and stable expression of marker genes into coffee tissues (Coffea arabica. L. cvs. Caturra and Catuaí). The effect of osmotic preculture length, osmotic concentration of medium, Helium pressure and target distance on transient expression of the uidA gene in coffee leaves and somatic embryos were tested. The highest transient uidA expression was obtained when Caturra (18.3±2.8) and Catuaí (6.8±2.0) leaves and Catuaí embryos (80.0±7.4) were cultured for 5h on Yasuda medium complemented with 0.5M Mannitol +0.5M Sorbitol. The combination of 1100psi and a target distance of 9cm resulted in the highest number of blue spots per Caturra leaf segment (23.6±3.9), whereas for the Catuaí variety the combination of 1100psi and a target distance of six (10.2±1.9) and nine (8.2±1.9) cm gave the highest number of blue spots per leaf segment. The optimized protocol was tested with pCAMBIA 1 301 (uidA gene and the hpt gene), pCAMBIA 1 305.2 (uidA version GUSPlus ™ and the hpt gene) and pCAMBIA 1 301-BAR (uidA gene and the bar gene). The highest number of blue spots was obtained when Caturra (54.6±5.7) and Catuaí (28.9±4.3) leaves were bombarded with pCAMBIA 1 305.2. Selection of bombarded coffee tissues with 100mg/l hygromicyn caused the oxidation of tissues. Rev. Biol. Trop. 57 (Suppl. 1): 151-160. Epub 2009 November 30.

A protocol for Coffea arabica L. cvs. Caturra and Catuaí plant regeneration via indirect somatic embryogenesis (ISE) was established. Furthermore, a biolistic mediated genetic transformation protocol was optimized for Catuaí callus aggregates. Maximum callus induction was obtained when Caturra (87%) and Catuaí (67%) leaves were cultured on Murashige and Skoog medium with 18.56 µM kinetin and 4.52 µM2,4-dichlorophenoxyacetic acid (2,4-D). Catuaí suspension cultures were established from embryogenic callus using liquid proliferation CP and Sli media and diffused light and darkness. The higher suspension cultures fresh weight was obtained using Erlenmeyer (1425.4 ± 354.9 mg) than Recipient for Automated Temporary Immersion System (RITA®) (518.6 ± 55.1 mg), whereas the dry weight of suspension cultures was not significantly affected by the culture system used. Higher number of embryos per vessel (307.6 ± 49.0) and their fresh weight (9.6 ± 1.5 mg) were obtained with semisolid R medium than S3 medium. The highest somatic embryo development (25.0 ± 2.7) and fresh weight (780.0 ± 85.4 mg) were obtained with 1 min of immersion every 8 hrs. Higher fresh weight of regenerated plantlets was obtained with liquid Yasuda medium in RITA® (124.6 ± 16.3 mg) than semisolid media (36.3 ± 11.3 mg). For genetic transformation, the effect of helium pressure (900 and 1550 psi), and target distance (9 and 12 cm) and plasmid (pCAMBIA 1301, pCAMBIA 1305.2 and pCAMBIA 1301-BAR) on transient uidA expression Catuaí suspension cultures were evaluated. The highest number of blue spots was obtained using 900 psi and 9 cm (125.8 ± 17.3). Stable uidA expression was observed on Catuaí callus aggregates transformed with pCAMBIA 2301 and cultured on 100 mg l-1 of kanamycin.

With the purpose of increasing the embryogenesis regeneration process in vitroplants obtained from somatic embryos of the indica rice variety CR-5272 (Oryza sativa L.), two independent experiments were performed. The first experiment consisted in the effect of combination of three concentrations of the gelling agent PhytagelTM (1.8, 2.4, and 3 gL-1) and four 2,4-D concentrations (2.26, 4.52, 6.78, and 9.05 mu M) on the induction and subsequent regeneration of embryogenic calli. On the second experiment, the pre-regeneration phase was modified; calli were subjected to darkness or diffuse light conditions for one, two, and three weeks. In embryogenesis induction, 35% calligenesis was obtained using the MS culture medium supplemented with 6.78 mu M of 2,4-D and 2.4 gL-1 PhytagelTM , whereas on the control treatment (MS medium supplemented with 9.05 mu M of 2,4-D and 3 gL-1 PhytagelTM ) 24% calligenesis was obtained. In addition, regeneration percentages were improved (22% and 16% for calli induced with the above treatments, respectively). Furthermore, in light exposure experiments, the best result was obtained by exposing the embryogenic calli to darkness for one week in pre-regeneration, followed by direct light exposure during the regeneration phase. Rev. Biol. Trop. 53(3-4): 361-368. Epub 2005 Oct 3.

La ingeniería genética y los alimentos derivados de los cultivos genéticamente modificados (CGMs) han sido objeto de debate a escala mundial, como ocurre históricamente con el surgimiento de tecnologías novedosas. Se cuestiona si los CGMs son seguros al ambiente y si los productos derivados de ellos son inocuos para los consumidores. Sobre la primera de esas inquietudes, la práctica se ha orientado a estudiar caso por caso, según las propias características del CGM, para minimizar su impacto en el ambiente. Estudios científicos en diversas latitudes han demostrado que no ha habido efectos dañinos en este particular. En cuanto a los alimentos derivados de los CGMs se han desarrollado sistemas de evaluación rigurosa para permitir su consumo y comercialización, y hay protocolos aprobados por la FAO y la OMS para garantizar su inocuidad. Hasta el momento, en ningún caso se han detectado contraindicaciones para la salud humana en los productos disponibles hoy en el mercado. Por su parte, Costa Rica estableció desde los años 90 un marco regulatorio en bioseguridad que se encarga de garantizar la seguridad para la salud y el ambiente en el manejo de los CGMs. Asimismo, se ha hecho una gran inversión estatal y privada en esta área, lo que le permitió a Costa Rica posicionarse en la región como uno de los primeros países con fortalezas en materia de bioseguridad y de investigación en ingeniería genética en centros de investigación nacionales. Cualquier intento de restringir o prohibir dicha actividad pondría en riesgo esa inversión, afectaría la generación de nuevo conocimiento para la toma de decisiones y el liderazgo alcanzado en el campo y nos privaría de los beneficios de esta prometedora tecnología.

Relationship of genetically modified crops with the environment and health of the Costa Rican human population. Genetic engineering and the food derived from genetically modified crops (GMCs) have been the center of debate worldwide, as has occurred historically with the advent of new technologies. Questions are derived from the potential impact of GMCs to the environment and the safety of the products to the consumers. In relation to the first inquiry, practice has been oriented to a case-by-case-study, according to the own characteristics of the GMC, in order to minimize its impact in the environment. Scientific studies in diverse latitudes of the world have demonstrated that GMCs in the market showed no adverse effects related to this issue. In relation to food derived from the GMCs, rigorous evaluation protocols have been developed and approved by FAO and WHO to guarantee the innocuousness of these products. Up to the moment, no contraindications for human health have been pointed out for the products that are available today in the market. In the particular case of Costa Rica, the country has established since the 90s a regulatory biosafety framework for the management of the GMCs, safeguarding the biodiversity of the country and the health of consumers. At the same time the country has made significant public and private investments in the field that allowed the country to obtain a leading position in biosafety in the region and genetic engineering research at national research centers. Any attempt to restrict or prohibit these activities in the country, will put in risk the previously described investment, will affect the generation of new knowledge for decision making and the leadership in the field, preventing the benefits derived from this promising technology. Rev. Biol. Trop. 52(3): 727-732. Epub 2004 Dic 15.

El gen que codifica por la proteína no estructural NS3 del virus de la hoja blanca de arroz (RHBV) se fusionó al extremo carboxilo del gen de la glutationa-S-transferasa y se expresó en la cepa JM83 de Escherichia coli. Se obtuvieron altas concentraciones de la proteína de fusion (GST-NS3) en forma insoluble. La proteína de fusión se fraccionó en geles de SDS-PAGE, se purificó por electroelución, y se utilizó para producir anticuerpos policlonales en conejo . El antisuero producido se absorbió con extractos crudos de E. coli. Extractos crudos de plantas de arroz sanas e infectadas con el RHBV se evaluaron por Western blots detectándose una banda de peso molecular similar al estimado para la proteína NS3 (23KDa) en las plantas infectadas con el virus. Los tejidos provenientes de plantas infectadas con el RHBV se analizaron por medio de microscopia inmunoelectrónica con oro colloidal marcado con anticuerpos contra la proteína NS3 y la nucleoproteína viral N. Se observó una acumulación in situ de la proteína NS3 en el citoplasma, pero no se detectó en los cuerpos de inclusion, vacuolas o cloroplastos. Se demostró que la proteína NS3 sigue el mismo patron de distribución que el de la nucleoproteína viral N del RHBV.

The non-structural NS3 protein gene from the rice hoja blanca virus (RHBV) was fused to the glutathione- S-transferase carboxilic end and expressed in Escherichia coli strain JM83. Large quantities of fusion protein were produced in insoluble form. The fusion protein was fractionated in SDS-PAGE and purified by electroelution, polyclonal antibodies were raised in rabbit and the antiserum was absorbed with bacterial crude extract. A band of similar size as that of NS3 protein was observed in Western blots using extracts from RHBV-infected rice plants. Immunoelectron microscopy with colloidal gold-labeled antibodies against NS3 protein and the viral nucleocapsid protein revealed in situ accumulation of NS3 protein in the cytoplasm but not in the viral inclusion bodies, vacuoles or chloroplasts of RHBV-infected plants, following the same pattern of distribution as the RHBV nucleocapsid protein. Rev. Biol. Trop. 52(3): 765-775. Epub 2004 Dic 15.