Mejora genética de la remolacha azucarera

130 Pags.- 13 Figs. Premio AIMCRA de Investigación 25 Aniversario. Libro editado por AIMCRA que autoriza la divulgación en abierto de esta obra a través de Digital.CSIC para usos científicos referenciándose adecuadamente.Como resumen, pensamos que en un período de unos 10 años, los híbridos diploides F1, comenzarán a impactar el mercado de variedades de remolacha, y reemplazarán gradualmente a las actuales variedades triploides. Estos desarrollos serán el resultado del incremento de la eficacia en los métodos de mejora poblacional, lo que permitirá la obtención de lineas con un mínimo de recesivos deletereos y una clara mejora en sus resultados. Estas lineas deberán ser mejoradas posteriormente a través de la introducción de diversos caracteres cualitativos, vía transformación genética, y de introducción de genes cuantitativos de interés, vía selección asistida por marcadores. Al igual que en maíz, la mejora de los híbridos dependerá mas de la mejora del valor de las lineas puras, que de un mayor grado de heterosis. Lairitegración de los métodos tradicionales con las nuevas tecnologías, creará un potencial para el desarrollo de variedades de remolacha azucarera, que no sólo ofrecerán mayores producciones de azúcar blanco, sino que exigirán menores aportes de agroquímicos y estarán más adaptadas a sistemas de cultivo económicos y sostenibles.Peer reviewe

Expression analysis of vernalization and day-length response genes in barley (Hordeum vulgare L.) indicates that VRNH2 is a repressor of PPDH2 (HvFT3) under long days

38 Pag., 1 Tabl., 6 Fig.The response to vernalization and the expression of genes associated with responses to vernalization (VRNH1, VRNH2, and VRNH3) and photoperiod (PPDH1 and PPDH2) were analysed in four barley (Hordeum vulgare L.) lines: ‘Alexis’ (spring), ‘Plaisant’ (winter), SBCC058, and SBCC106 (Spanish inbred lines), grown under conditions of vernalization and short days (VSD) or no vernalization and long days (NVLD). The four genotypes differ in VRNH1. Their growth habits and responses to vernalization correlated with the level of expression of VRNH1 and the length of intron 1. ‘Alexis’ and ‘Plaisant’ behaved as expected. SBCC058 and SBCC106 showed an intermediate growth habit and flowered relatively late in the absence of vernalization. VRNH1 expression was induced by cold for all genotypes. Under VSD, VRNH1 expression was detected in the SBCC genotypes later than in ‘Alexis’ but earlier than in ‘Plaisant’. VRNH2 was repressed under short days while VRNH1 expression increased in parallel. VRNH3 was detected only in ‘Alexis’ under NVLD, whereas it was not expressed in plants with the active allele of VRNH2 (SBCC058 and ‘Plaisant’). Under VSD, PPDH2 was expressed in ‘Alexis’, SBCC058, and SBCC106, but it was only expressed weakly in ‘Alexis’ under NVLD. Further analysis of PPDH2 expression in two barley doubled haploid populations revealed that, under long days, HvFT3 and VRNH2 expression levels were related inversely. The timing of VRNH2 expression under a long photoperiod suggests that this gene might be involved in repression of PPDH2 and, indirectly, in the regulation of flowering time through an interaction with the day-length pathway.This study was funded by grants AGL2007-63625 and HH2008-0013 from the Spanish Ministry of Science and Technology and by the European Regional Development Fund. Germplasm from the SBCC is maintained with funding from project RFP2004-00015-00-00. MCC was supported by an I3P Predoctoral Fellowship from CSIC.Peer reviewe

Joint analysis for heading date QTL in small interconnected barley populations

42 Pag., 5 Tabl., 4 Fig. The definitive version is available at: http://www.springer.com/life+sciences/plant+sciences/journal/11032The purpose of the present work is to validate the effect of the main QTL determining heading date in a set of 281 doubled haploid lines of barley, derived from 17 small interconnected populations, whose parents are cultivars commonly used in the Spanish barley breeding program. We used 72 molecular markers distributed across the seven chromosomes, particularly in regions known to contain flowering time genes or QTL. A combined linkage map over the 17 populations was constructed. The lines were evaluated in four field trials: two autumn sowings and two winter sowings, and in two treatments at a greenhouse trial, under controlled conditions of photoperiod and temperature. We have found that it is possible to carry out QTL detection in a complex germplasm set, representative of the materials used in an active breeding programme. In most cases two alleles per QTL were detected, though polymorphism of flanking markers was notably higher. The results revealed that there is a set of QTL that accounts for an important percentage of the phenotypic variation, suitable for marker assisted selection. Also, the role of the regions carrying the photoperiod response genes Ppd-H1 and Ppd-H2, the vernalization response genes Vrn-H1 and Vrn-H2, and the earliness per se locus Eam6, of which allele-specific or closely linked markers were available, was confirmed. These results support the use of this kind of approach for the validation of QTL found in single cross population studies, or to survey allelic diversity in plant breeding sets of materials.This work was supported by the Spanish Ministry of Education and Research (Projects AGL2001-2289, including a scholarship granted to Mr. Alfonso Cuesta-Marcos, and AGL2004-05311) and by the European Regional Development Fund.Peer reviewe

Analysis of powdery mildew resistance in the Spanish barley core collection

24 Pag., 4 Tabl., 2 Fig. The definitive version is available at: www3.interscience.wiley.comThe Spanish Barley Core Collection, consisting of one hundred and fifty-nine landrace-derived inbred lines and sixteen cultivars, was characterized for resistance to powdery mildew (Blumeria graminis f. sp. hordei) using a set of 27 isolates with a wide spectra of virulences/avirulences on most of the genes expected to occur in Europe. No landrace-derived line and no cultivar were resistant to all the isolates but at least three landraces showed infection types below 2 for 23 isolates. Twenty-two landraces and one cultivar showed resistance against half of the isolates used. Eleven isolates were sufficient to separate the majority of resistance profiles. In total, thirty-four resistance spectra were detected and fourteen resistance genes/alleles were postulated alone or in combination: MlLa, Mlh, Mlg, Mla22, Mla7(Mlu), Mla7(Mlk), Mlk, Mla12, Mla9, Mla3, Mla6(Mla14), Mlra and Mla1. The majority of resistance spectra are composed only by one line. Resistance in twenty-one landrace-derived lines and four cultivars was based on either unidentified genes or combinations of known and unknown genes/alleles. Therefore, the SBCC may be a source for broadening the genetic base of powdery mildew resistance.This research was funded by projects AGL2004-05311 and AGL2007-63625, granted by the Spanish Ministry of Science and Innovation. C.S. holds an I3P-Doc contract from CSIC. C.S. was supported by mobility fellowships from DFG, CSIC and Fundación Caja Inmaculada.Peer reviewe

HvFT1 (VrnH3) drives latitudinal adaptation in Spanish barleys

29 Pag., 5 Tabl., 4 Fig. The definitive version is available at: http://www.springer.com/life+sciences/plant+sciences/journal/122Flowering time is an important factor in the adaptation of barley varieties to environmental conditions and maximizing yield potential (Boyd et al. 2003; Cockram et al. 2007a; Cuesta-Marcos et al. 2009), by synchronizing the plant cycle to the prevailing environmental conditions. Flowering time is a complex trait that shows an almost continuous variation in cereals. The investigation of the genetic control of flowering time in barley has benefited from the comparative use of floral pathways in Arabidopsis thaliana (Cockram et al. 2007a) and rice, via the identification of candidate genes through orthology. The variation in flowering time is mainly due to variations in genes regulated by day length (photoperiod) or long exposures to low temperature (vernalization) (Laurie et al. 1995; Trevaskis et al. 2003; Dubcovsky et al. 2005). In barley, three genes are responsible for the vernalization requirement: VrnH1 (isolated by map-based cloning in diploid wheat, Yan et al. 2003), VrnH2 (identified by positional cloning, Yan et al. 2004) and VrnH3 (identified by homology to a known gene from Arabidopsis thaliana, Yan et al. 2006). VrnH1 is induced by vernalization and promotes the transition from vegetative to reproductive development. VrnH2 is a floral repressor that delays flowering until the plants are vernalized. The VrnH3 gene seems to be orthologous to the A. thaliana floral pathway integrator FT (FLOWERING LOCUS T) gene (Yan et al. 2006; Faure et al. 2007; Turck et al. 2008; Kikuchi et al. 2009). In A. thaliana, FT expression increases in the leaves when plants are exposed to inductive day length. In barley, expression of orthologous HvFT1 (synonymous to VrnH3) is induced by long day conditions and promotes flowering (Hemming et al. 2008). The winter growth habit of barley requires the presence of a recessive VrnH1 allele, together with an active VrnH2 allele (Cockram et al. 2007b; Hemming et al. 2009). Vernalization induces VrnH1 under both short and long days, which then represses VrnH2. Distelfeld et al. (2009) reported that the interactions among the three vernalization genes generate a feedback regulatory loop that once started, leads to an irreversible induction of flowering. The function of HvFT1 has started to be unraveled only recently. There is now mounting evidence supporting the role of the FT protein in Arabidopsis (and corresponding proteins in other species) as an important part of the florigen (Corbesier et al. 2007; Tamaki et al. 2007). Kikuchi et al. (2009) presented strong evidence suggesting that HvFT1 plays a central role in promoting flowering, integrating the photoperiod and vernalization pathways. HvFT1 expression seems to be regulated by the major photoperiod response genes: PpdH1 under LD conditions and PpdH2 under SD conditions. There are evidences on the adaptive role played by VrnH1, VrnH2 and PpdH1 during the expansion of the crop, facilitating its adaptation to new agroecological niches (Cockram et al. 2007a; Jones et al. 2008). Does VrnH3-HvFT1 also have an adaptive role? We know that the phenotypic effect of HvFT1 on flowering time can be very large (Yan et al. 2006), and therefore may be an important factor for the final determination of barley flowering time. Other open questions on this gene are: to what environmental cue does VrnH3 respond, temperature or photoperiod? What effect does it have on flowering time under natural conditions? To address these questions, we analyzed the polymorphism and the phenotypic effect of this gene on a collection of Spanish barley landraces and its variation at the sequence level, and validated its effect on a segregating population.This work was supported by the Spanish Ministry of Science and Innovation (Projects AGL2007-63625 and RTA01-088-C3) and by the European Regional Development Fund. A Djemel was supported by a fellowship from IAMZ-CIHEAM. S Yahiaoui and L Ponce were supported by fellowships from AECID-Spanish Ministry of Foreign Affairs and Cooperation.Peer reviewe

Métodos de mejora en plantas alógamas. Métodos de selección

13 Pags.- Figs.El empleo o no de la selección masal para un cierto carácter en una población particular debe ser juzgada a la vista de: a) El punto al que la población ha sufrÍdo ya selección y está bien adaptada. b) La heterogenidad genética de la población. c) La proporción de varianza aditiva para el carácter en selección. d) La pasibilidad de controlar la varianza ambiental. e) Las posibles interferencias a causar por la competencia intergenotípica. f) La posibilidad de aplicar selección estrictamente sin caer en consanguinidad. g) Las posibles correlaciones negativas entre el carácter en selección y otros carácteres importantes. h) La utilidad práctica y económica de otros métodos alternativos.Peer reviewe

Estudios sobre el espigado de la remolacha azucarera, Beta vulgaris L.

192 Pag.En el presente trabajo doctoral se incluyen tres estudios realizados sobre el espigado de la remolacha azucarera. En el primero se trabaja sobre la aparición de espigado en los cultivos otoñales del Sur de España. En el segundo estudio, basado en trabajos realizados en diez zonas, para multiplicación de semilla de remolacha, se investigan las condiciones óptimas que dichas zonas deben reunir en lo que respecta al espigado, para obtener una correcta multiplicación sin pérdidas de resistencia en los materiales multiplicados. El tercer estudio se ha basado en algunos de los factores que rigen el forzamiento de espigado en ambiente controlado.Peer reviewe

Obtención de variedades híbridas monogérmenes de remolacha azucarera, adaptadas a las condiciones de cultivo españolas

127 Pags.- Figs.Se presenta un programa de investigación sobre mejora de remolacha azucarera, encaminado a la obtención de hí­bridos monogérmenes adaptados a las condiciones de cultivo españolas. Tras un análisis de las características de cultivo en España, y de las características genéticas de los objeti­vos, se programan la realización de trabajos a medio y largo plazo, dentro de un esquema continuo de mejora vegetal. Se examinan los resultados ya obtenidos así como las novedades que el programa presentará para el cultivo remo­lachero español.Peer reviewe

Caracterización agronómica, fenológica, cualitativa y molecular de la colección nuclear de cebadas españolas

El presente proyecto planteaba el paso siguiente a la construcción, por nosotros mismos, de la Colección Nuclear de Cebadas Españolas, que es una representación esquemática de la variabilidad genética de las cebadas ancestralmente cultivadas en nuestro país. Para la explotación completa de estos materiales autóctonos en el Programa Nacional de Mejora de Cebadas, que estamos llevando a cabo los grupos integrantes de este proyecto, se realizó el mismo, que ha comprendido los objetivos siguientes: - Caracterización agronómica, mediante ensayos de campo en ambientes contrastantes y representativos, incluyendo la evaluación de respuestas a factores productores de estreses bióticos y abióticos. - Caracterización fenológica, mediante ensayos en invernadero con protocolos desarrollados por nosotros, para identificar la respuesta de estos genotipos a la vernalización y el fotoperiodo. - Caracterización maltero-cervecera/pienso, mediante análisis de cebada y malta. - Caracterización molecular, mediante el uso de marcadores SSRs y STS