12 research outputs found
Nota corta. Detecci贸n mediante PCR multiplex y caracterizaci贸n de cepas no toxig茅nicas de Pseudomonas syringae pv. phaseolicola de distintas zonas de Espa帽a
The efficient control of halo blight, caused by Pseudomonas syringae pv. phaseolicola, is primarily based on the use of pathogen-free seed. Detection of the pathogen in seeds is currently carried out with high-sensitive methods based on the detection by PCR of genes involved in the biosynthesis of phaseolotoxin, which was believed to be produced by all strains of the pathogen with epidemiological importance. However, field epidemics of halo blight in the county of Castilla y Le贸n, Spain, are often associated to nontoxigenic isolates of P. syringae pv. phaseolicola, which cannot be detected using current molecular and serological methods. The results presented in this work show the existence of nontoxigenic isolates of P. syringae pv. phaseolicola in areas other than Castilla y Le贸n, indicating the need to establish a reliable methodology for seed certification. A simple two-step methodology is presented with the aim to identify both types of isolates that is based on a multiplex enrichment PCR of seed soakates and on pathogenicity assays.El control eficiente de la grasa de la jud铆a causada por Pseudomonas syringae pv. phaseolicola se basa principalmente en la utilizaci贸n de semilla libre del pat贸geno. La detecci贸n del pat贸geno en semilla se efect煤a mediante m茅todos altamente sensibles basados en la detecci贸n por PCR de los genes responsables de la bios铆ntesis de la faseolotoxina, la cual, hasta ahora, se consideraba que era sintetizada por todas las cepas del pat贸geno con importancia epidemiol贸gica. Sin embargo, en la Comunidad de Castilla y Le贸n, Espa帽a, las epidemias de grasa de la jud铆a en campo se asocian frecuentemente con cepas no toxig茅nicas de P. syringae pv. phaseolicola, que no pueden ser detectadas con los m茅todos moleculares y serol贸gicos actuales. Los resultados presentados en este trabajo demuestran la existencia de aislados no toxig茅nicos de P. syringae pv. phaseolicola en zonas distintas de Castilla y Le贸n, lo que implica la necesidad de establecer una metodolog铆a fiable para la certificaci贸n de semillas de jud铆a. Con este prop贸sito, se presenta un sencillo protocolo en dos fases que permite la identificaci贸n de los dos tipos de aislados, y que se basa en una PCR multiplex con enriquecimiento a partir de extractos de semilla y en ensayos de patogenicidad
Seis ciclos de selecci贸n recurrente S1 en dos sint茅ticos de ma铆z espa帽oles
European flint x US dent is the most common heterotic pattern used in early maize (Zea mays L.) breeding programs in Spain. Two synthetic maize populations, EZS1 (formed from four Spanish flint populations), and EZS2 (formed from four American dent populations), were developed in Zaragoza, Spain. These synthetics, which showed heterotic behaviour, were subjected to six cycles of S1 recurrent selection for increased grain yield and reduced lodging. The aim of this study was to investigate the effectiveness of selection on these and other agronomic traits in both synthetics. The original populations, EZS1C0 and EZS2C0, and the six cycles of selection of both, were evaluated at two locations over two years. Over the six selection cycles, the average yield of EZS1 and EZS2 increased by 0.82 Mg/ha and 0.93 Mg/ha per cycle respectively, while lodging decreased by 2.76% and 2.44% per cycle respectively. Changes due to selection were significant for all test traits in both synthetics. It was concluded that S1 selection is effective in improving the yield of, and reducing lodging in, both synthetics.El patr贸n heter贸tico de ma铆z (Zea mays L.) m谩s utilizado en Espa帽a, en programas de mejora gen茅tica, es el formado por el germoplasma liso europeo y el dentado de origen norteamericano. En Zaragoza, Espa帽a, se obtuvieron dos poblaciones sint茅ticas de ma铆z, EZS1 (formada por cuatro poblaciones lisas espa帽olas), y EZS2 (formada por cuatro poblaciones dentadas americanas). Estas poblaciones mostraron un buen comportamiento heter贸tico inicial y fueron sometidas a seis ciclos de selecci贸n recurrente intrapoblacional, por el m茅todo de familias S1, para mejora de rendimiento y de encamado de planta. El objetivo de este trabajo fue estudiar la eficacia de la selecci贸n sobre el rendimiento y otros caracteres agron贸micos en ambas poblaciones sint茅ticas. Las poblaciones originales (EZS1C0 y EZS2C0) y los seis ciclos de selecci贸n de ambas fueron evaluadas en dos localidades durante dos a帽os. En el conjunto de los seis ciclos, y para el car谩cter rendimiento, el incremento promedio por ciclo fue de 0,93 Mg/ha en EZS1 y de 0,82 en EZS2. El encamado de planta decreci贸 2,76% y 2,44%, por ciclo, respectivamente. Las ganancias gen茅ticas debidas a la selecci贸n fueron significativas en ambas poblaciones y para todos los caracteres. Se puede concluir que en ambas poblaciones la selecci贸n por el m茅todo de familias S1 fue eficaz para la mejora del rendimiento y la disminuci贸n del encamado
Potencial para la mejora de germoplasma de ma铆z precoz liso adaptado a condiciones de clima templado
Early-maturing flint maize germplasm could be an important alternative for the development of new early-maturing commercial hybrids adapted to cooler summer regions. Our objective was to evaluate the performance of flint populations in crosses with four testers from different heterotic groups, as sources of new potential inbred lines. Ten flint maize populations were crossed to four inbred testers representing Reid Yellow Dent, Lancaster Sure Crop and two Spanish flint heterotic groups. Topcrosses were evaluated in four environments in north eastern Spain in 2001 and 2002. The main type of gene action expressed was additive. All populations except Enano Norte帽o/Vasco and Hembrilla Norte帽o/Vasco, had a higher specific combining ability in crosses with Reid Yellow Dent or Lancaster Sure Crop testers. Average yields were better when populations were crossed with dent lines rather than with the flint inbred line EP42. These results could be useful in the development of new inbred lines that would increase genetic variability present in commercial European flint maize.La evaluaci贸n de germoplasma liso precoz de ma铆z podr铆a ser importante como una alternativa para el desarrollo de nuevos h铆bridos comerciales precoces adaptados a regiones templadas y potencialmente 煤tiles para producir grano de alta calidad. Nuestros objetivos fueron evaluar el potencial de poblaciones lisas precoces y estimar el rendimiento de este germoplasma en cruzamientos con probadores de diferentes grupos heter贸ticos para el desarrollo de h铆bridos precoces de ma铆z grano. Diez poblaciones de ma铆z grano se cruzaron con cuatro probadores que representan Reid Yellow Dent, Lancaster Sure Crop y dos grupos heter贸ticos europeos. Los cruzamientos fueron evaluados en cuatro ambientes en el noreste de Espa帽a durante 2001 y 2002, siendo la expresi贸n g茅nica expresada aditiva. Todas las poblaciones cruzadas, excepto Enano Norte帽o/Vasco y Hembrilla Norte帽o/Vasco, mostraron una mayor aptitud combinatoria espec铆fica en cruzamientos con probadores Reid Yellow Dent o Lancaster Surecrop. El mejor rendimiento medio se produjo cuando todas las poblaciones se cruzaron con las l铆neas dentadas en lugar de con la l铆nea lisa EP42. Estos resultados podr铆an ser 煤tiles para desarrollar nuevas l铆neas puras que incrementen la variabilidad presente en el ma铆z liso comercial europeo
Comunicaci贸n corta. Selecci贸n masal divergente para precocidad en una variedad sint茅tica espa帽ola de ma铆z
Eight cycles of divergent mass selection for flowering time were performed in the synthetic maize (Zea mays L.) population Lazcano (EZS9) from Guipuzcoa, Spain. A trial with a randomised block design plus three replicates was then performed at two locations in northeastern Spain, and over two years, to compare flowering time in the original population and the material produced in the eight selection cycles. Linear regression coefficients were determined to estimate the average rate of selection response per cycle. Genetic gains with respect to the vegetative cycle and other major agronomic traits were obtained. Direct selection responses were significant and grain yield maintained. No negative correlated responses were obtained for any agronomic trait. Divergent mass selection for early flowering was therefore found to be efficient in this synthetic population.Se llevaron a cabo ocho ciclos de selecci贸n masal divergente para precocidad en la poblaci贸n sint茅tica de ma铆z (Zea mays L.) Lazkano (EZS9), originaria de Guip煤zcoa, Espa帽a. Se realiz贸 un ensayo en dos localidades del Noreste de Espa帽a y durante dos a帽os, con un dise帽o de bloques completos al azar y tres repeticiones, con el fin de comparar el periodo de floraci贸n en la poblaci贸n original y los ocho ciclos de selecci贸n. Se han determinado los coeficientes de correlaci贸n lineal para estimar la respuesta media por ciclo de selecci贸n. Asimismo, se han calculado las ganancias gen茅ticas para el ciclo vegetativo y los principales caracteres agron贸micos. La respuesta directa a la selecci贸n fue significativa, manteni茅ndose el rendimiento. No se encontraron respuestas negativas correlacionadas con otros caracteres agron贸micos. La selecci贸n divergente realizada para precocidad fue, por lo tanto, eficiente en esta poblaci贸n sint茅tica
Conservaci贸n de cultivares de patata (Solanum tuberosum L.) mediante criopreservaci贸n
The shoot-tips of plants of 10 potato cultivars maintained by micropropagation were frozen (ultra rapid freezing) and cryopreserved in liquid nitrogen for three months. The survival rate of the thawed specimens exceeded 50%, and even reached 100% in the case of the cultivar F茅nix. The average regeneration rate was between 2.5% and 22.0%, depending on the cultivar and the presence of extra plant hormones in the regeneration medium. Cytogenetic stability was confirmed by flow cytometry: no polyploid plants were found. The regenerated plants showed vegetative development characteristics of their respective cultivars.Se ha aplicado la criopreservaci贸n mediante el m茅todo de congelaci贸n ultrarr谩pida a 10 cultivares de patata mantenidos por micropropagaci贸n. Para ello se congelaron y conservaron en nitr贸geno l铆quido meristemos apicales. La supervivencia tras la descongelaci贸n, transcurrido un periodo de tres meses, fue superior al 50% en todos los casos, alcanzando en alg煤n cultivar, como Fenix, hasta el 100% de los meristemos congelados. Las tasas de regeneraci贸n se situaron entre el 2,5% y el 22,0%, dependiendo del cultivar empleado y el uso de fitohormonas en el medio MS s贸lido con agarosa. La estabilidad citogen茅tica fue evaluada mediante citometr铆a de flujo, no encontrando en ning煤n caso poliploides. Las plantas regeneradas mostraron un desarrollo vegetativo aparentemente id茅ntico a los cultivares originales
Evaluaci贸n agron贸mica de poblaciones dulces de ma铆z derivadas de cruzamientos entre ma铆z dulce y ma铆z grano
The adaptation of sweetcorn (Zea mays L.) to Spanish growing conditions needs to be improved, something that could be achieved by incorporating traits from field corn populations. The aim of the present study was to analyse the performance of sweetcorn populations carrying the genes sugary1 (su1) or shrunken2 (sh2), as well as sugary enhancer double mutants (su1 se1), produced by crosses between sweetcorn donor populations and the Spanish field corn populations Lazcano, Oroso and Rastrojero. The three field corn populations plus the su1, su1 se1 and sh2 populations derived from them, as well as the su1, su1 se1, and sh2 donor populations used in the crosses with the field corn populations, were evaluated for their agronomic performance. Several hybrids were used as controls. Assessments were made in Zaragoza (NE Spain) and Pontevedra (NW Spain) over two years. The ability of the field corn populations to improve the sweetcorn varieties was not greatly affected by the sweetcorn mutant involved. The field corn populations chosen as donors for improving sweetcorn must depend on the growing conditions in mind. Sweetcorn populations derived Oroso would appear to be the most favourable for northern Spain, while those derived from Rastrojero would appear to be the most suitable for inland Spain, although other field corn populations are still to be examined.La adaptaci贸n del ma铆z dulce (Zea mays L.) a las condiciones espa帽olas debe ser mejorada y esto se puede realizar mediante la incorporaci贸n de factores de adaptaci贸n de las poblaciones locales. El objetivo del presente estudio fue evaluar el resultado de las poblaciones de ma铆z dulce sugary1 (su1), sugary enhancer (su1 se1), y shrunken2 (sh2) derivadas de las poblaciones de ma铆z grano Lazcano, Oroso y Rastrojero. Las tres poblaciones originales junto con las su1, su1 se1 y sh2 convertidas y las tres poblaciones utilizadas como donantes de los genes su1, su1 se1, y sh2, fueron evaluadas para comportamiento agron贸mico, utilizando varios h铆bridos como testigos. Los ensayos se realizaron en dos localidades espa帽olas (Zaragoza y Pontevedra) durante dos a帽os. La capacidad de las poblaciones de ma铆z grano para mejorar el ma铆z dulce no se vio en gran medida afectada por el tipo de mutante incorporado. Las poblaciones de ma铆z grano utilizadas como donantes dependen de las condiciones de crecimiento, siendo Oroso la m谩s favorable para el Norte de Espa帽a. Las poblaciones de ma铆z dulce derivadas de Rastrojero parecen ser las m谩s convenientes para la Espa帽a interior, no obstante pueden explorarse otro tipo de poblaciones de ma铆z grano
Construction of a potato transcriptome map based on the cDNA-AFLP technique
The cDNA驴AFLP technique can be used to monitor differential gene expression, but also for linkage mapping. Extending previous works, we have now constructed an integrated linkage map of the potato transcriptome based on the said technique that has a length of around 800 cM and contains nearly 700 transcriptome derived fragments (TDFs). At the same time, most of these markers are anchored to the bins of a highly saturated reference map in potato, combining in this way the information provided by different marker types. Moreover, we detected and confirmed an elevated degree of allelic fragments with this marker type, which was present in nearly half of all primer combinations and involved around 20% of all fragments. These properties were particularly useful to establish anchor points for integrating the individual parental linkage maps. Comparative expression profiling in different plant materials revealed that only a few additional TDFs were obtained which were specific for mature leaves or tubers compared to the TDFs present in whole in vitro plants. Since TDF markers are derived from coding regions, they generally also represent sequences with a biological function. In four case studies, co-migrating TDFs in different Solanum wild species always represented potential alleles based on elevated homologies among them. Two resistance gene homologs were identified by analysing TDFs, which were co-located with known QTLs
Identification of candidate genes involved in the response to different abiotic stresses in potato (Solanum tuberosumL.)
Plants growing in natural habitats are exposed to multiple environmental stresses resulting from abiotic factors such as heat, drought, and cold, which have a significant impact on cultivated potato. We have evaluated in two Solanum tuberosumvarieties, Soprano and Kondor, the adaptation to different abiotic stresses as heat, cold, and drought. For this purpose plants of both varieties were stressed, and when they showed symptoms, RNA extraction was carried out and a cDNA library for each sample was constructed. The objective of this study was to detect and analyse the genes involved in the responses to abiotic stresses in potato.The assay generated transcriptome sequences from both varieties, and a total of 5.579.655 reads and 8420 putative candidate genes were generated. 4.027 of the candidate genes were polymorphic and presented a different number of patterns defined by a varying number of SNPs. Many of the generated candidate genes showed differential expression, since the candidate gene was present in the stressed plant, but not in the control plant. The application of this methodology allows us to detect numerous candidate genes or specific alleles/allele combinations, which are differentially expressed in specific samples after the application of different abiotic stresses. This will be useful to identify superior alleles which can be used in Marker Assisted Selection for resistance and tolerance to abiotic stressesLas plantas que crecen en h谩bitats naturales est谩n expuestas a m煤ltiples estreses ambientales resultantes de factores abi贸ticos como el calor, la sequ铆a y el fr铆o, que tienen un impacto significativo en la papa cultivada. Se ha evaluado en dos variedades de Solanum tuberosumL. Soprano y Kondor, la adaptaci贸n a diferentesestreses abi贸ticos como calor, fr铆o y sequ铆a. Para ello, las plantas de ambas variedades fueron estresadas y cuando mostraron s铆ntomas se llev贸 a cabo la extracci贸n de ARN y se construy贸 una biblioteca de ADNc para cada muestra. El objetivo de este estudio fue detectar y analizar los genes involucrados en las respuestas al estr茅s abi贸tico en papa. El ensayo gener贸 secuencias de transcriptomas de ambas variedades, con un total de 5579655 lecturas y 8420 genes candidatos posibles. 4027 de los genes candidatos fueron polim贸rficos y presentaron un n煤mero diferente de patrones definidos por un n煤mero variable de SNPs. Muchos de los genes candidatos generados mostraron una expresi贸n diferencial, ya que el gen candidato estaba presente en la planta estresada, pero no en la control. La aplicaci贸n de esta metodolog铆a nos permite detectar numerosos genes candidatos o combinaciones espec铆ficas de alelos, que se expresan diferencialmente despu茅s de la aplicaci贸n de diferentes estreses abi贸ticos. Esto ser谩 煤til para identificar alelos superiores que se pueden usar en la Selecci贸n Asistida por Marcadores para la resistencia y tolerancia a estreses abi贸tico
Ampliando la frontera agr铆cola de la papa (Solanum tuberosum L.) para disminuir los efectos del cambio clim谩tico
A temporary immersion system was tested to accelerate the procurement of pre-basic seed category of two varieties for agroindustry, Superchola and Diacol-Capiro (Solanum tuberosum L.) in addition to the autotrophic hydroponic system. The results of the proposed system presented several advantages compared to in vitro produced seed and semi-hyroponic seedlings. The vegetative part was increased in the total number of node segments obtained by the bioreactor, 322 and 264 for Superchola and Diacol-Capiro respectively. These values corresponded to the production of 81 test tubes (1,8 x 14 cm), which occupied an area of 2041,2 cm2. The production cycle was also shorter than the traditional in vitro agar culture system in fifteen days. The multiplication rates for Superchola and Diacol-Capiro were 1:9 and 1:8. The production rate per area was > 366 minitubers per m2 in Superchola and 225 minituber per m2 in Diacol-Capiro. The average yield of 3.75 kg. m-2 is higher than those obtained in vitro and semi-hydroponic seedlings. Superchola achieved the best response with superior yields (tuber quantity) 20% over Diacol-Capiro. The cost/profit ratio of 1.27 defined Superchola as the most profitable under the proposed seed production system with a return of 0.27 USD per invested dollar. This system can be adapted for commercial in vitro potato seed propagationLa mayor铆a de los cultivares tradicionales de papa no est谩n adaptadas a las condiciones del cultivo provocadas por el cambio clim谩tico, que hacen disminuir dr谩sticamente los rendimientos e incluso perder completamente la cosecha en muchos lugares desfavorecidos. En pa铆ses en v铆as de desarrollo, como en Latinoam茅rica, esta situaci贸n afecta a la base alimentaria de las comunidades, y al sostenimiento econ贸mico y social; los agricultores optan por migrar en b煤squeda de otros medios de subsistencia. Ante esta problem谩tica, se estableci贸 un consorcio de ocho instituciones reconocidas de siete pa铆ses para identificar y desarrollar cultivares de papa adaptados al cambio clim谩tico y desarrollar metodolog铆as y herramientas moleculares eficientes que aceleren este proceso. El proyecto logr贸 cultivares con mejor adaptaci贸n a condiciones ambientales adversas en zonas productoras y zonas desfavorecidas. Se mejor贸 la competitividad del cultivo de la papa, que aument贸 la superficie de su cultivo, y se diversific贸 la producci贸n agraria, asegurando el suministro de alimentos en zonas deprimidas. Los agricultores cuentan con cultivares, con buena adaptaci贸n a los cambios en temperatura, precipitaci贸n, y mayor resistencia al tiz贸n tard铆o (Phytophthora infestans). Los investigadores disponen de metodolog铆as adecuadas para la evaluaci贸n de resistencias a estreses bi贸ticos y abi贸ticos y disponen de marcadores moleculares 煤tiles para predecir el comportamiento agron贸mico y la adaptaci贸