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[ES] El tomate es uno de los cultivos hortícolas más importantes del mundo. Su producción se ha basado en una sobrefertilización, especialmente nitrogenada, para maximizar las cosechas. Esto ha llevado a una contaminación de los suelos y los acuíferos, y ha contribuido al cambio climático. Los objetivos que se plantean para el desarrollo de una agricultura sostenible requieren una disminución del aporte de nitrógeno a los cultivos, evitando a su vez una reducción significativa de la producción. Además de mejoras en el manejo de los cultivos, en este contexto es de gran importancia la obtención de cultivares con mayor eficiencia en el uso del nitrógeno (NUE), especialmente en condiciones de aporte reducido de nitrógeno. El desarrollo de estos cultivares se ha de basar en un mejor conocimiento de los procesos fisiológicos implicados. La NUE está fundamentalmente definida por procesos de captación y asimilación de nitrógeno (N), así como de distribución y movilización de los compuestos nitrogenados al órgano cosechado, en este caso el fruto. Cabe destacar la estrecha relación del metabolismo del carbono (C), como fuente de esqueletos carbonados para su asimilación, con el de N. En este trabajo se pretende caracterizar la asimilación y partición de C y N en cultivares de tomate que en estudios previos han mostrado una NUE diferencial. Se determinará la captación de ambos elementos midiendo la tasa fotosintética, así como el contenido en C y N elementales en los diferentes órganos durante el desarrollo de la planta. Además, se medirá el contenido en carbohidratos metabolizables (azúcares y almidón), aminoácidos y proteínas totales. Dado que la NUE de las plantas depende del aporte de N, los estudios se realizarán en plantas fertilizadas tanto con niveles de nitrógeno suficientes como subóptimas. Este trabajo permitirá relacionar la capacidad de captación, asimilación y distribución de C/N con su NUE en distintas condiciones de disponibilidad de N., [EN] Tomato is one of the most important horticultural crops in the world. Intensive production systems have been based on an elevated use of fertilizers, especially nitrogenous, to maximize harvests. This has led to pollution of soils and aquifers and has contributed to climate change. The objectives set for the development of sustainable agriculture require a reduction in the nitrogen input to crops, while avoiding a significant reduction in production. In addition to improvements in crop management, in this context it is of great importance to obtain crops with greater nitrogen use efficiency (NUE), especially under conditions of reduced nitrogen supply. The development of these cultivars must be based on a better understanding of the physiological processes involved. The NUE is fundamentally defined by nitrogen (N) uptake and assimilation processes, as well as the distribution and mobilization of nitrogenous compounds to the harvested organ, in this case the fruit. It is worth highlighting the close relationship between the metabolism of carbon (C), as a source of carbon skeletons for their assimilation, with that of N. This work has characterized the assimilation and partition of C and N in tomato crops that in previous studies have shown a differential NUE. The uptake of both elements has been determined by measuring the photosynthetic rate, as well as the content of elemental C and N in the different organs during the development of the plant. In addition, the content of metabolizable carbohydrates (soluble sugars and starch) and free amino acids has been measured. Given that the NUE of the plants depends on the input of N, the studies will be carried out in fertilized plants with both sufficient and suboptimal levels. In this study, the capacity for uptake, assimilation and distribution of C / N has been related to its NUE in different genotypes under different conditions of availability of N. It has been determined that genotype CV70 is of particular intere

[EN] The development of high nitrogen use efficiency (NUE) cultivars under low N inputs is required for sustainable agriculture. To this end, in this study, we analyzed the impact of long-term suboptimal N conditions on the metabolome and transcriptome of tomato to identify specific molecular processes and regulators at the organ scale. Physiological and metabolic analysis revealed specific responses to maintain glutamate, asparagine, and sucrose synthesis in leaves for partition to sustain growth, while assimilated C surplus is stored in the roots. The transcriptomic analyses allowed us to identify root and leaf sets of genes whose expression depends on N availability. GO analyses of the identified genes revealed conserved biological functions involved in C and N metabolism and remobilization as well as other specifics such as the mitochondrial alternative respiration and chloroplastic cyclic electron flux. In addition, integrative analyses uncovered N regulated genes in root and leaf clusters, which are positively correlated with changes in the levels of different metabolites such as organic acids, amino acids, and formate. Interestingly, we identified transcription factors with high identity to TGA4, ARF8, HAT22, NF-YA5, and NLP9, which play key roles in N responses in Arabidopsis. Together, this study provides a set of nitrogen-responsive genes in tomato and new putative targets for tomato NUE and fruit quality improvement under limited N supply.

[ES] En el contexto actual de aumento de la población mundial y de cambio climático, se hace necesario del desarrollo de nuevos cultivares que permitan incrementar las cosechas bajo condiciones de producción sostenible. Esto es de especial relevancia en el caso del nitrógeno, ya que el sobreabonado realizado para maximizar las cosechas está provocando importantes problemas de contaminación de suelos y atmósfera. El tomate es el principal cultivo hortícola en España, con una producción cercana a los 5 millones de toneladas anuales. Desde su introducción, la mejora de esta especie se ha dirigido a la obtención de variedades tolerantes a enfermedades, con alto índice de cosecha, y más recientemente, con mejor calidad organoléptica. S. pimpinellifolium es una especie antecesora del tomate cultivado que se ha empleado en diversos trabajos de mejora para la introducción en tomate, mediante ILs, de caracteres relacionados con la resistencia a enfermedades y calidad del fruto. Estudios recientes en una colección de ILs de S. pimpinellifolium y tomate han mostrado algunos genotipos con mayor vigor de crecimiento. Además, resultados preliminares del grupo de investigación sugieren que esta especie muestra una menor reducción de crecimiento en condiciones de limitación en el suministro de nitrógeno. En este contexto, el objetivo principal del presente trabajo es la identificación de caracteres de S. pimpinellifolium relacionados con la producción en condiciones de limitación en el aporte de nitrógeno. Para ello, se estudiará el crecimiento, producción y calidad de fruto en una colección de ILs de esta especie silvestre en tomate comercial. Se seleccionarán para su estudio genético y fisiológico posterior aquellas líneas que muestren una mayor eficiencia en la acumulación de biomasa y partición de asimilados al fruto, manteniendo su calidad bajo aporte reducido de nitrógeno., [EN] In the current context of increasing world population and climate change, it is necessary to develop new cultivars that allow increasing yields under sustainable production conditions. This is specially relevant in the case of nitrogen due to over-fertilization carried out to maximize harvests, which is causing important problems of contamination of soils and atmosphere. Tomato is the main horticultural crop in Spain, with a production close to 5 million tons per year. Since its introduction, the improvements of this species has been aimed to obtain varieties that are tolerant to diseases, with a high harvest index and more recently with better organoleptic quality. S.pimpinellifolium is an ancestor species of the cultivated tomato that has been used in various breeding Works for the introduction into tomato by ILs of characters related to resistance to diseases and fruit quality. Recent studies in a collection of S.pimpinellifolium and tomato ILs have shown some genotypes with greater growth vigor. In addition, preliminary results from the research group suggest that this species shows a lower growth reduction under conditions of limited nitrogen supply. In this context, the main goal of this project is the identification os S.pimpinellifolium characters related to production under conditions of limited nitrogen suppley. Therefore, the growth production and quality of fruit will be studied in a collection of ILs of this wild species in commercial tomato. Those lines that show greater efficiency in the accumulation of biomass and partition of assimilates to the fruit will be selected for theis subsequent genetic and physiological study, keeping their quality under reduced nitrogen uptake.

[EN] Tomato is one of the most widely cultivated vegetable crops and a model for studying fruit biology. Although several genes involved in the traits of fruit quality, development and size have been identified, little is known about the regulatory genes controlling its growth. In this study, we characterized the role of the tomato SlCDF4 gene in fruit development, a cycling DOF-type transcription factor highly expressed in fruits. The targeted overexpression of SlCDF4 gene in the fruit induced an increased yield based on a higher amount of both water and dry matter accumulated in the fruits. Accordingly, transcript levels of genes involved in water transport and cell division and expansion during the fruit enlargement phase also increased. Furthermore, the larger amount of biomass partitioned to the fruit relied on the greater sink strength of the fruits induced by the increased activity of sucrose-metabolising enzymes. Additionally, our results suggest a positive role of SlCDF4 in the gibberellin-signalling pathway through the modulation of GA(4) biosynthesis. Finally, the overexpression of SlCDF4 also promoted changes in the profile of carbon and nitrogen compounds related to fruit quality. Overall, our results unveil SlCDF4 as a new key factor controlling tomato size and composition.

[EN] Cycling Dof Factor (CDF) transcription factors (TFs) are involved in multiple processes related to plant growth and development. A member of this family, CDF3, has recently been linked in Arabidopsis to the regulation of primary metabolism and abiotic stress responses, but its role in crop production under stress is still unknown. In this study, we characterized tomato plants overexpressing the CDF3 genes from Arabidopsis and tomato and analyzed their effects on growth and yield under salinity, additionally gaining deeper insights into the molecular function of these TFs. Our results provide evidence for higher biomass production and yield in the 35S::AtCDF3 and 35S::SICDF3 plants, likely due to a higher photosynthetic capacity resulting in increased sucrose availability. Transcriptome analysis revealed that CDF3 genes regulate a set of genes involved in redox homeostasis, photosynthesis performance and primary metabolism that lead to enhanced biomass production. Consistently, metabolomic profiling revealed that CDF3 evokes changes in the primary metabolism triggering enhanced nitrogen assimilation, and disclosed that the amount of some protective metabolites including sucrose, GABA and asparagine were higher in vegetative tissues of CDF3 overexpressing plants. Altogether these changes improved performance of 35S::AtCDF3 and 35S::SICDF3 plants under salinity conditions. Moreover, the overexpression of CDF3 genes modified organic acid and sugar content in fruits, improving variables related to flavor perception and fruit quality. Overall, our results associate the CDF3 IF with a role in the control of growth and C/N metabolism, and highlight that overexpression of CDF3 genes can substantially improve plant yield.

Crocins, the glucosides of crocetin, are present at high concentrations in saffron stigmas and accumulate in the vacuole. However, the biogenesis of the saffron chromoplast, the changes during the development of the stigma and the transport of crocins to the vacuole, are processes that remain poorly understood. We studied the process of chromoplast differentiation in saffron throughout stigma development by means of transmission electron microscopy. Our results provided an overview of a massive transport of crocins to the vacuole in the later developmental stages, when electron dense drops of a much greater size than plastoglobules (here defined crocinoplast ) were observed in the chromoplast, connected to the vacuole with a subsequent transfer of these large globules inside the vacuole. A proteome analysis of chromoplasts from saffron stigma allowed the identification of several well-known plastid proteins and new candidates involved in crocetin metabolism. Furthermore, expressions throughout five developmental stages of candidate genes responsible for carotenoid and apocarotenoid biogenesis, crocins transport to the vacuole and starch metabolism were analyzed. Correlation matrices and networks were exploited to identify a series of transcripts highly associated to crocetin (such as 1-Deoxy-D-xylulose 5-phosphate synthase (DXS), 1-Deoxy-D-xylulose 5-phosphate reductoisomerase (DXR), carotenoid isomerase (CRTISO), Crocetin glucosyltransferase 2 (UGT2), etc.) and crocin (e.g., -carotene desaturase (ZDS) and plastid-lipid-associated proteins (PLAP2)) accumulation; in addition, candidate aldehyde dehydrogenase (ADH) genes were highlighted.

[EN] The genus Crocus belonging to the family Iridaceae, is known for its cultivated species, saffron (Crocus sativus L.). The genus includes about 100 species, many of which are of interest as ornamentals for their products or secondary metabolism, and others are exclusively wild. On the whole, they are a source of genetic variability of enormous interest. The rapid disappearance of the culture of saffron in Europe due to the significant amount of manpower required, has led to significant genetic erosion. In order to slow down and improve this situation, several national and European programs for the collection, multiplication, and characterization of germplasm of saffron and related species were initiated. In this context, this Thesis aims to complete the existing collections and characterize the available germplasm of the Spanish wild species of the genus Crocus, conserved in the Plant Germplasm Bank of the Center for Research in Agroforestry in Albaladejito (Cuenca). Seven wild species of this genus can be found in Spain, which are both autumn flowering species (C. serotinus, C. clusii, C. nudiflorus and C. cambessedesii) and spring flowering species (C. nevadensis, C. carpetanus and C. vernus), and in this work a morphological, physiological, biochemical and molecular characterization of them has been carried out. After a thorough review of the locations of these species in Spain, we have collected accessions from different locations in which their presence was described. We have developed location maps, and the description of the ecosystems these species inhabit. Of this set of accessions, a maximum of 60, which form a representation of the observed variability, were characterized morphologically. It should be noted that a microscopic characterization of the anatomy of the leaves and seed coat also identifies most species. A total of 115 accessions, representing different populations of each species collected, have been characterized phenologically. In additio, [ES] El género Crocus perteneciente a la familia de las Iridáceas, es conocido por su especie cultivada, el azafrán (Crocus sativus L.). El género incluye aproximadamente 100 especies, muchas de las cuales tienen interés como ornamentales o por sus productos de metabolismo secundario, y otras son exclusivamente silvestres. En su conjunto, constituyen una fuente de variabilidad genética de enorme interés. La rápida desaparición del cultivo del azafrán en Europa, debido a la importante cantidad de mano de obra que requiere, ha conducido a una importante erosión genética. Con el fin de frenar y mejorar esta situación, se han iniciado varios programas de ámbito nacional y europeo para la recolección, multiplicación, y caracterización de germoplasma de azafrán y especies afines. En ese contexto, se enmarca esta Tesis que tiene como objetivo completar las colecciones existentes y caracterizar el germoplasma disponible de especies silvestres españolas del género Crocus, del Banco de Germoplasma Vegetal del Centro de Investigación Agroforestal de Albaladejito (Cuenca). En España pueden encontrarse 7 especies silvestres de este género, que son tanto de floración otoñal (C. serotinus, C. clusii, C. nudiflorus y C. cambessedesii) como primaveral (C. nevadensis, C. carpetanus y C. vernus), y en este trabajo se ha llevado a cabo una caracterización morfológica, fisiológica, bioquímica y molecular de las mismas. Tras una revisión minuciosa de las citas sobre la localización de estas especies en España, se han conseguido entradas de distintas áreas de las zonas en las que se ha descrito su presencia. Se han elaborado mapas de localización, así como la descripción de los ecosistemas que habitan estas especies. De este conjunto de entradas, un máximo de 60, que configuran una representación de la variabilidad observada, fueron caracterizadas morfológicamente. Hay que destacar una caracterización microscópica de la anatomía de las hojas y de la cubierta de las semillas que permite ta, [CA] El gènere Crocus pertanyent a la família de les Iridaceae, és conegut per la seua espècie conreada, el safrà (Crocus sativus L.). El gènere inclou aproximadament 100 espècies, moltes de les quals tenen interès com a ornamentals o pels seus productes de metabolisme secundari, i altres són exclusivament silvestres. El seu conjunt, constitueix una font de variabilitat genètica d'enorme interès. La ràpida desaparició del cultiu del safrà a Europa, a causa de la important quantitat de mà d'obra que requereix, ha conduït a una important erosió genètica. Per tal de frenar i millorar aquesta situació, s'han iniciat diversos programes d'àmbit nacional i europeu per a la recol·lecció, multiplicació, i caracterització de germoplasma de safrà i espècies afins. En aquest context, s'emmarca aquesta Tesi que té com a objectiu completar les col·leccions existents i caracteritzar el germoplasma disponible d'espècies silvestres espanyoles del gènere Crocus, del Banco de Germoplasma Vegetal del Centro de Investigación Agroforestal de Albaladejito (Cuenca). A Espanya es poden trobar 7 espècies silvestres d'aquest gènere, que són tant de floració tardoral (C. serotinus, C. clusii, C. nudiflorus i C. cambessedesii) com primaveral (C. nevadensis, C. carpetanus i C. vernus), i en aquest treball s'ha dut a terme una caracterització morfològica, fisiològica, bioquímica i molecular de les mateixes. Després d'una revisió minuciosa de les cites sobre la localització d'aquestes espècies a Espanya, s'han aconseguit entrades de diferents àrees de les zones en què s'ha descrit la seua presència. S'han elaborat mapes de localització, així com la descripció dels ecosistemes que habiten aquestes espècies atenent: tipus de sòl, altitud, clima, comunitat vegetal i els estressos abiòtics o biòtics més freqüents. D'aquest conjunt d'entrades, un màxim de 60, que configuren una representació de la variabilitat observada, van ser caracteritzades morfològicament. Cal destacar una caracterització microscò

[ES] Durante el siglo XX, la mejora de la producción de los cultivo se basó en la optimización de las prácticas de cultivo, incluyendo fertilizantes, pesticidas, riego, y la selección de cultivares. Actualmente, la creciente demanda de producción, junto con la limitación en la disponibilidad de tierras y agua de riego de calidad, hace necesario el desarrollo de nuevas variedades con una capacidad mayor de producción de biomasa y tolerancia a estreses ambientales. Además, en el contexto de una agricultura sostenible y menos agresiva con el medio ambiente, es necesario reducir el uso de fertilizantes. En este sentido, estas variedades deben presentar una mejor eficiencia en el uso del nitrógeno, uno de los principales macronutrientes requeridos por la planta y responsable de la contaminación de acuíferos. La generación de plantas transgénicas con mayor capacidad de producción de biomasa por sobreexpresión de genes individuales relacionados con la fijación fotosintética de carbono o la asimilación de nitrógeno ha dado resultados limitados, ya que se trata de caracteres multigénicos. En este sentido, la utilización de factores de transcripción, que regulan la expresión de múltiples genes simultáneamente, parece una estrategia prometedora. La sobreexpresión de genes de una familia de factores de transcripción específicos de plantas, los genes Dof (DNA-binding with one finger), han incrementado la producción en plantas de maíz o mijo. En el presente trabajo se ha caracterizado el papel del gen Dof21 de Arabidopsis thaliana en el metabolismo de carbono y nitrógeno en tomate. Para ello se han cultivado plantas en condiciones de invernadero, con tres niveles de aporte de nitrógeno (100, 60 y 30% del aporte completo), y se ha determinado la producción de biomasa, la capacidad fotosintética, el contenido en carbohidratos metabolizables, el contenido total en C y N, así como la actividad enzimática de la enzima nitrato reductasa y la expresión del gen PEP carboxilasa y la quina, [EN] During the 20th century, the improvement in the crop production was based on the optimization of the growing techniques, including fertilisers, pesticides, irrigation and cultivars selection. Currently, the increasing demand in production along with the limitation of land and irrigation water availability makes it necessary the development of new varieties with a greater capacity of biomass production and environmental stress tolerance. Furthermore, in the context of a sustainable and less aggressive agriculture, it is essential to reduce the fertilisers used. Accordingly, these new varieties should be more efficiency regarding the use of nitrogen, which is one of the principal macronutrients required by the plant and responsible of the aquifer contamination. The generation of transgenic plants with an increased biomass production capacity through the overexpression of genes related to the photosynthetic fixation of carbon or the nitrogen assimilation has provided limited results, due to the fact that these are multigenic characters. In this regard, the utilization of transcription factors, which regulate the expression of multiple genes simultaneously, could be a promising strategy. The overexpression of a specific plant family of transcription factors, the Dof (DNA-binding with one finger), has increased the production in maize, millet plants. In the present study, it has been characterized the role of the Arabidopsis thaliana gen Dof21 in the carbon and nitrogen metabolism in tomato. For this purpose, tomato plants have been cultivated in greenhouse conditions with three levels of nitrogen input (100, 60 and 30% of the full input). Finally, it has been determinated the biomass production, the photosynthetic capacity, the metabolizable carbohydrates content, the carbon and nitrogen content, the activity of the nitrate reductase enzyme and the expression of PEP carboxylase and the kinase SnRK1. The Dof21 overexpression increases the photosynthetic rate, the av

[EN] The present state of knowledge concerning developmental processes and the secondary metabolism of saffron, Crocus sativus L. (Iridaceae), along with the genes involved in these processes so far known, is reviewed. Flowers and corms constitute the most valuable parts of saffron. Corm and flower development are two key aspects to be studied in saffron to increase the yield and quality of the spice, to raise its reproductive rate, and to implement new production systems. Important knowledge about the physiology of flowering and vegetative growth has been acquired in recent years, but there is still only limited information on molecular mechanisms controlling these processes. Although some genes involved in flower formation and meristem transition in other species have been isolated in saffron, the role of these genes in this species awaits further progress. Also, genes related with the synthesis pathway of abscisic acid and strigolactones, growth regulators related with bud endodormancy and apical dominance (paradormancy), have been isolated. However, the in-depth understanding of these processes as well as of corm development is far from being achieved. By contrast, saffron phytochemicals have been widely studied. The different flower tissues and the corm have been proved to be an important source of phytochemicals with pharmacological properties. The biotechnological prospects for saffron are here reviewed on the basis of the discovery of the enzymes involved in key aspects of saffron secondary metabolism, and we also analyze the possibility of transferring current knowledge about flowering and vegetative propagation in model species to the Crocus genus.

[EN] In this work we have done a research study about the annual variation in production of photoassimilates and mobilizing them into sinks in the alternate bearing 'Salustiana' sweet orange (Citrus sinensis (L.) Osb.), and its relation to the reproductive behavior. The alternate bearing of this variety is due to the low intensity of flowering obtained after a year of a high yield, and not to the decreased of fruit set. The photosynthetic rate does not show major seasonal variations, being the changing environmental conditions among the different days in a month the main source of variation. No significant differences were observed in AN among trees on and off, although in the same on tree, the leaves of shoots that bear fruits have a slightly lower photosynthetic rate (10%) than shoots without fruit. The photosynthetic capacity remains stable throughout the first year of life of the leave, and decreases by 20% for the second-one. Soluble sugars in leaves of 'Salustiana' maintain a fairly constant level throughout the year, whereas the excess of fixed carbon is used for the production of starch, which is the carbohydrate with greater variations. The variation in carbohydrates meets the changing demand of the various sinks. In off trees, the starch content is higher than in on trees between March and August, and the maximum difference occurs at the end of fruit drop, in June. From September until March, no differences in carbohydrate content among trees on and off are observed. At the time of full blossom (April), the concentration of carbohydrates in on tree leaves decreases dramatically. Most of the stocks during the off year seem destined to the formation of surplus flowers, with a cost of dry matter of about 6 kg. From these observations it can be concluded that the reserves of carbohydrates in leaves do not have a regulatory role in the floral induction which takes place between November and February, also in flower development, which starts between February and, [ES] En este trabajo se ha estudiado la variación anual de la producción de fotoasimilados y la movilización de los mismos hacia sumideros en la variedad alternante de naranjo dulce 'Salustiana' (Citrus sinensis (L.) Osb.), y su relación con el comportamiento reproductivo. Las observaciones indican que el comportamiento alternante de esta variedad, es debido a la baja intensidad de floración que se obtiene tras un año de elevada cosecha, y no a una disminución del cuajado. La tasa fotosintética no manifiesta grandes variaciones estacionales, siendo las condiciones ambientales cambiantes entre los diferentes días de un mes la principal fuente de variación. No se observan diferencias significativas en AN entre árboles on y off, pero en un mismo árbol on, en las hojas de brotes con fruto es menor (10%). La capacidad fotosintética permanece estable a lo largo del primer año de vida de la hoja, y disminuye un 20% durante el segundo. Los azúcares solubles en hojas mantienen un nivel prácticamente constante durante todo el año, mientras que el exceso de carbono fijado se destina a la producción de almidón, que es el carbohidrato que presenta mayores variaciones. En los árboles off, el contenido de almidón en hojas es superior que en los árboles on entre marzo y agosto, presentando la diferencia máxima al final de la caída de fruto, en junio. Desde septiembre hasta marzo, no se observan diferencias en el contenido en carbohidratos entre árboles on y off. En el momento de plena floración (abril), la concentración de carbohidratos en árboles on disminuye considerablemente, con lo que la mayor parte de las reservas almacenadas durante el año off parecen destinadas a la formación de flores excedentes, cuyo coste es de unos 6 kg de materia seca. Por tanto, las reservas de carbohidratos en hojas no tienen un papel regulador ni durante la inducción floral por bajas temperaturas, que tiene lugar entre noviembre y febrero, ni en el desarrollo de las flores, que se inicia entre febre, [CA] En aquest treball s'ha estudiat la variació anual de la producció de fotoassimilats i la mobilització dels mateixos cap a embornals en la varietat alternant de taronger dolç 'Salustiana' (Citrus sinensis (L.) Osb.), i la seva relació amb el comportament reproductiu. El comportament alternant d'aquesta varietat és a causa de la baixa intensitat de floració que s'obté després d'un any d'elevada collita, i no a una disminució del quallat. La taxa fotosintètica no mostra grans variacions estacionals, sent les condicions ambientals canviants entre els diferents dies d'un mes la principal font de variació. No s'observen diferències significatives en AN entre arbres on i off, però en un mateix arbre on, les fulles de brots amb fruit presenten una taxa fotosintètica lleugerament menor (10%) que les de brots sense fruit. La capacitat fotosintètica roman estable al llarg del primer any de vida de la fulla, i disminueix un 20% durant el segon. Els sucres solubles en fulles de 'Salustiana' mantenen un nivell pràcticament constant durant tot l'any, mentre que l'excés de carboni fixat es destina a la producció de midó, que és el carbohidrat que presenta majors variacions. La variació en carbohidrats s'ajusta als canvis en la demanda dels diferents embornals. En els arbres off, el contingut de midó és superior que en arbres on entre març i agost, sent la diferència màxima al final de la caiguda de fruit, en juny. Des de setembre fins a març, no s'observen diferències en el contingut en carbohidrats entre arbres on i off. En el moment de plena floració (abril), la concentració de carbohidrats en les fulles dels arbres on disminueix considerablement, amb el que la major part de les reserves emmagatzemades durant l'any off semblen destinades a la formació de flors excedents, el cost de les quals és d'uns 6 kg de matèria seca. Per tant, les reserves de carbohidrats en fulles no tenen un paper regulador ni durant la inducció floral per baixes temperatures, que té lloc entre novemb

[EN] DNA binding with One Finger (DOF) transcription factors are involved in multiple aspects of plant growth and development but their precise roles in abiotic stress tolerance are largely unknown. Here we report a group of five tomato DOF genes, homologous to Arabidopsis Cycling DOF Factors (CDFs), that function as transcriptional regulators involved in responses to drought and salt stress and flowering-time control in a gene-specific manner. SlCDF15 are nuclear proteins that display specific binding with different affinities to canonical DNA target sequences and present diverse transcriptional activation capacities in vivo. SlCDF15 genes exhibited distinct diurnal expression patterns and were differentially induced in response to osmotic, salt, heat, and low-temperature stresses. Arabidopsis plants overexpressing SlCDF1 or SlCDF3 showed increased drought and salt tolerance. In addition, the expression of various stress-responsive genes, such as COR15, RD29A, and RD10, were differentially activated in the overexpressing lines. Interestingly, overexpression in Arabidopsis of SlCDF3 but not SlCDF1 promotes late flowering through modulation of the expression of flowering control genes such as CO and FT. Overall, our data connect SlCDFs to undescribed functions related to abiotic stress tolerance and flowering time through the regulation of specific target genes and an increase in particular metabolites.

[EN] Tomato is one of the most important horticultural crops worldwide, and is cultivated in semi-arid regions in which soil and groundwater salinity is an increasing limitation to yield. The assessment of the responses of new cultivars to salt and the comparisons among cultivars and wild species are of great interest in tomato breeding. This assay provides a reproducible and reliable method for screening tomato responses to NaCl salinity under hydroponic conditions in growth chambers. Although NaCl is the most commonly used salt in salinity studies, other salts such as Na2SO4, MgCl2 or MgSO4, usually found in saline soils, can also be assayed (Nebauer et al., 2013). Plants can be maintained for 30-45 days under the described conditions, although significant effects on growth can be observed after 10 days, depending on the salt and concentration used.

[EN] Salinity is an important environmental constraint to crop productivity in arid and semiarid regions of the world. The evaluation of the responses to salinity of different Arabidopsis ecotypes or transgenic lines is important to identify and investigate the role of different key genes. These new characterized genes involved in the response to salinity stress are of great interest to be incorporated in crops breeding programs. Here we provide a reproducible method to evaluate the performance of Arabidopsis lines to salinity stress by analysing primary and lateral root growth and fresh weight of plants grown under in vitro conditions in growth chambers. Even though NaCl is the most frequent used salinity tests, other salts (e.g. KCl, MgCl2) can be also evaluated by this method. Arabidopsis plants can be maintained for 15-20 days in these conditions, although effects on growth and biomass can be observed, depending on the used salt and concentration, within the first 10 days.

[EN] Background: In saffron (Crocus sativus), new corms develop at the base of every shoot developed from the maternal corm, a globular underground storage stem. Since the degree of bud sprouts influences the number and size of new corms, and strigolactones (SLs) suppress growth of pre-formed axillary bud, it was considered appropriate to investigate SL involvement in physiology and molecular biology in saffron. We focused on two of the genes within the SL pathway, CCD7 and CCD8, encoding carotenoid cleavage enzymes required for the production of SLs. Results: The CsCCD7 and CsCCD8 genes are the first ones isolated and characterized from a non-grass monocotyledonous plant. CsCCD7 and CsCCD8 expression showed some overlapping, although they were not identical. CsCCD8 was highly expressed in quiescent axillary buds and decapitation dramatically reduced its expression levels, suggesting its involvement in the suppression of axillary bud outgrowth. Furthermore, in vitro experiments showed also the involvement of auxin, cytokinin and jasmonic acid on the sprouting of axillary buds from corms in which the apical bud was removed. In addition, CsCCD8 expression, but not CsCCD7, was higher in the newly developed vascular tissue of axillary buds compared to the vascular tissue of the apical bud. Conclusions: We showed that production and transport of auxin in saffron corms could act synergistically with SLs to arrest the outgrowth of the axillary buds, similar to the control of above-ground shoot branching. In addition, jasmonic acid seems to play a prominent role in bud dormancy in saffron. While cytokinins from roots promote bud outgrowth. In addition the expression results of CsCCD8 suggest that SLs could positively regulate procambial activity and the development of new vascular tissues connecting leaves with the mother corm.

[EN] The fruit is the main sink organ in Citrus and captures almost all available photoassimilates during its development. Consequently, carbohydrate partitioning and starch content depend on the crop load of Citrus trees. Nevertheless, little is known about the mechanisms controlling the starch metabolism at the tree level in relation to presence of fruit. The aim of this study was to find the relation between the seasonal variation of expression and activity of the genes involved in carbon metabolism and the partition and allocation of carbohydrates in 'Salustiana' sweet orange trees with different crop loads. Metabolisable carbohydrates, and the expression and activity of the enzymes involved in sucrose and starch metabolism, including sucrose transport, were determined during the year in the roots and leaves of 40-year-old trees bearing heavy crop loads ('on' trees) and trees with almost no fruits ('off' trees). Fruit altered photoassimilate partitioning in trees. Sucrose content tended to be constant in roots and leaves, and surplus fixed carbon is channeled to starch production. Differences between 'on' and 'off' trees in starch content can be explained by differences in ADP-glucose pyrophosphorylase (AGPP) expression/activity and alpha-amylase activity which varies depending on crop load. The observed relation of AGPP and UGPP (UDP-glucose pyrophosphorylase) is noteworthy and indicates a direct link between sucrose and starch synthesis. Furthermore, different roles for sucrose transporter SUT1 and SUT2 have been proposed. Variation in soluble sugars content cannot explain the differences in gene expression between the 'on' and 'off' trees. A still unknown signal from fruit should be responsible for this control.

Saffron is a triploid sterile crop with a low vegetative propagation rate, which prevents the widespread use of selected genotypes. Despite efficient in vitro propagation via direct organogenesis being very interesting, high contamination levels and low propagation rates preclude the commercial use of this technique. In order to obtain a source of explants for the in vitro multiplication of saffron that allows low contamination levels and efficient propagation, daughter corms were produced by storing non-planted mother corms at low temperatures (1-3 degrees C) for 9 months. This method avoids field cultivation and yields more corms than field production (8 vs. 3 corms per mother corm). Corms produced under cold storage conditions were in vitro sprouted on media with a high level of cytokinins (5 mg l(-1) 6-benzylaminopurine or 1 mg l(-1) thidiazuron) and 0.5 mg l(-1) naphthalene acetic acid, and sprouted buds were cultivated on the same media. After 8 weeks of culture, multiple shoot primordia emerged from the base of the sprouted buds with no callus formation, and up to 400 shoot primordia were produced from one initial mother corm. These shoot primordia can be elongated and 90% produce corms. The high multiplication rate, lack of contamination, and the fact that multiplication occurs through direct organogenesis make the method suitable for the propagation of selected genotypes. Otherwise shoot clusters can be maintained for 6-7 months. However for longer maintenance periods, shoot proliferation capacity by direct organogenesis diminishes, and the emergence of somaclonal variation cannot be ruled out.

[EN] The objective of this work was to study the influence of fruit load on CO2 assimilation in the leaves of citrus trees presenting alternate bearing habits, and the importance of this factor on photosynthetic rate variability throughout the year and under regular cropping conditions. The photosynthetic rate was measured on 60 days throughout the year on field-grown sweet orange plants under natural conditions in the Valencian Community, the most important citrus-producing area of Spain. The experiments were performed on the 'on' (high crop) and 'off' (low crop) bearing 40-year-old Salustiana sweet orange trees growing in the same orchard. Gas exchange and fluorescence parameters were measured during the year in young and old leaves on sun-exposed branches with and without fruit in the 'on' trees, and in fruitless branches of the 'off' trees. In non-manipulated Citrus trees, fruit load has no significant effect in any season on the photosynthetic rate in the leaves from branches without fruit. However, in high crop trees, the leaves of branches bearing fruit present a slightly lower photosynthetic rates (approx. 10%) than those of fruitless branches. Variations in mineral content (N, K and P) might explain not only these differences, but also the lower photosynthesis rate observed in old leaves (13-24 month-old leaves). Environmental conditions were the main factor for the variation of the photosynthetic rate, with variability of the monthly mean photosynthetic rate being much lower than that between days in the same month.

A major constraint limiting saffron cultivation is the difficulty of obtaining high quality corms for propagation. There is limited knowledge about the physiology of vegetative development of saffron. The aim of this work was to analyse the relative contribution of different carbon sources (leaf photosynthetic activity and mother corm reserves) to the growth of vegetative organs and to analyse the influence of internal and external factors on the photosynthetic processes sustaining corm growth. The photosynthetic rate and changes in biomass were measured over the course of the vegetative growing season. The influence of the size of the mother corm, the cultivation method used (greenhouse versus field) and water availability on saffron production was assessed. Most of the remaining mother corm reserves after flowering were depleted during root and leaf development. After these organs reached their maximum size, the growth of replacement corms was initiated, and this development primarily relied on photosynthesis. Saffron mother corm reserves only contributed 10% to the biomass during vegetative development. The photosynthetic rate was consistently very high (26 mu mol m(-2) s(-1)) throughout the year but was reduced in plants from the largest corms. A sink capacity limitation arose during growth of replacement corms since the increase of biomass was limited before total leaf senescence. Saffron grown under greenhouse conditions exhibited traits characteristic of plants grown under low-irradiance, even after the saffron plants were transferred to the field. This fact limits the production of replacement corms in this environment. A decrease in the photosynthetic rate was observed under water stress, but the supply of water to the leaves from the corms and roots was found to maintain a still high photosynthetic rate (12 mu mol m(-2) s(-1)) even at highly negative soil water potentials.

[EN] Since 2007, the European Commission AGRI GEN RES 018 "CROCUSBANK" action has permitted the creation of the alleged World Saffron and Crocus Collection (WSCC), a unique collection which contains a representation of the genetic variability present in saffron crop and wild relatives at global scale. At present the germplasm collection, housed at the Bank of Plant Germplasm of Cuenca (BGV-CU, Spain), consists of 572 preserved accessions representing 47 different Crocus species (including saffron Crocus) and is expected to increase up to more than 600 accessions by the end of CROCUSBANK action (May 2011). The preserved biodiversity of saffron (Crocus sativus L.) covers a wide range of the genetic variability of the crop and currently consists of 220 accessions from 15 countries: 169 of these come from European cultivation countries, 18 from commercial areas in non EU countries, 26 from regions of minimal or relict production and/or from abandoned fields and 7 from commercial nurseries. The non-saffron Crocus collection currently comprises 352 accessions: 179 collected from the wild in 12 countries of natural distribution, 24 from donations of public and private institutions, 91 from commercial nurseries and 58 acquired from BGV-CU collection management. Here we provide a record of collections, activities concerns and current strategies for documentation, conservation, characterisation, and management of the collection as important tools for researchers with interest in these valuable genetic resources.

Photosynthesis down-regulation due to an imbalance between sources and sinks in Citrus leaves could be mediated by excessive accumulation of carbohydrates. However, there is limited understanding of the physiological role of soluble and insoluble carbohydrates in photosynthesis regulation and the elements triggering the down-regulation process. In this work, the role of non-structural carbohydrates in the regulation of photosynthesis under a broad spectrum of source-sink relationships has been investigated in the Salustiana sweet orange. Soluble sugar and starch accumulation in leaves, induced by girdling experiments, did not induce down-regulation of the photosynthetic rate in the presence of sinks (fruits). The leaf-to-fruit ratio did not modulate photosynthesis but allocation of photoassimilates to the fruits. The lack of strong sink activity led to a decrease in the photosynthetic rate and starch accumulation in leaves. However, photosynthesis down-regulation due to an excess of total soluble sugars or starch was discarded because photosynthesis and stomatal conductance reduction occurred prior to any significant accumulation of these carbohydrates. Gas exchange and fluorescence parameters suggested biochemical limitations to photosynthesis. In addition, the expression of carbon metabolism-related genes was altered within 24 h when strong sinks were removed. Sucrose synthesis and export genes were inhibited, whereas the expression of ADP-glucose pyrophosphorylase was increased to cope with the excess of assimilates. In conclusion, changes in starch and soluble sugar turnover, but not sugar content per se, could provide the signal for photosynthesis regulation. In these conditions, non-stomatal limitations strongly inhibited the photosynthetic rate prior to any significant increase in carbohydrate levels. © The Author 2011. Published by Oxford University Press. All rights reserved.

En el presente trabajo se han ensayado 62 accesiones de azafrán procedente de diferentes países (Azerbaiyán, Francia, India, Irán, Italia, Marruecos, Nueva Zelanda, España y Turquía), de las que 48 son españolas y 14 pertenecen a países principalmente mediterráneos. Todas ellas fueron seleccionadas según su disponibilidad en el Banco de Germoplasma de Albadalejito (Cuenca) y según su representatividad en cuanto al origen, procediendo de zonas de producción actual o donde su presencia es relíctica. El ensayo fue llevado a cabo en la parcela experimental del Banco de Germoplasma de Albadalejito siguiendo un diseño de bloques al azar con tres réplicas por accesión y diez cormos por replica. Se evaluaron caracteres relacionados con: la fenología (precocidad y periodo de floración), la morfología floral (ancho y largo de tépalos externos e internos, patrón de venación y longitud de anteras, del filamento del estambre y del estigma), la producción (número de flores por cormo y peso seco de especia por flor), el desarrollo vegetativo (número de brotes formados por cormo, número de hojas formadas por cormo y por brote principal, longitud máxima de la hoja adulta y anchura de la misma) y también se caracterizó la tasa fotosintética. Los resultados indican que todos los caracteres estudiados presentan variabilidad entre las entradas ensayadas a excepción de la anchura de hoja. La máxima variabilidad se presenta para los caracteres relacionados con el tamaño floral y con el peso seco de especia. Tiene interés la variabilidad observada para la precocidad y el número de hojas por cormo, como también la tasa fotosintética. Todos estos caracteres son de gran utilidad para la mejora genética del azafrán, ya que permitiría mejorar el manejo del cultivo, aumentar la producción de especia y obtener nuevas variedades de interés ornamental entre otros aspectos.

[EN] The aim of this work was to assess the relation between carbohydrate levels and flower and fruit production, as well as the role of carbohydrates on CO(2) fixation activity, by analysis of leaves, twigs and roots from the alternate bearing 'Salustiana' cultivar of sweet orange (Citrus sinensis [L.] Osbeck). A heavy crop load (on year) did not affect photosynthesis activity when compared to non-fruiting trees (off year). Fruiting trees accumulated most of the fixed carbon in mature fruits, whilst no accumulation was observed in roots before harvest. Non-fruiting trees transported part of the fixed carbon to the roots and mobilize it for growth processes and, at the end of the season (December), store it as reserves. Reserve carbohydrates accumulation in leaves started by early December for both tree types, showing the same levels in on and off trees until spring bud sprouting. A heavy flowering after an off year caused the rapid mobilization of the stored reserves, which were exhausted at full bloom. We found no evidence on carbon fixation regulation by either fruit demand or carbohydrate levels in leaves. Carbohydrate reserves played little or no role over fruit set, which actually relied on current photosynthesis