L’assemblage des espèces (leurs présences/absence) dans une communauté naturelle est la conséquence de plusieurs mécanismes de filtrage réalisés par l'environnement. Parmi ces filtres, le filtre abiotique sélectionne les espèces capables de tolérer les conditions environnementales locales. La variation de la disponibilité de l'eau dans le sol est l'un des principaux gradients environnementaux selon lesquels les espèces végétales sont différemment réparties. Considérant l’hypothèse que les traits fonctionnels et leurs relations sont hiérarchisées, les préférences d’habitat des espèces le long de gradients environnementaux devraient être déterminées par une combinaison de traits physiologiques et morpho-anatomiques hiérarchisés. Au cours de ce doctorat, mon objectif général est d'identifier les traits fonctionnels morphologiques, anatomiques et physiologiques de tolérance à la sécheresse qui peuvent prédire la présence des espèces le long d'un gradient d’hydrologie des sols. Plus spécifiquement, nous cherchons à savoir : (i) Quels sont les traits physiologiques qui reflètent le mieux la tolérance à la sécheresse ? (ii) Quelles sont les relations entre les traits morpho-anatomiques et les traits physiologiques de tolérance ? (iii) Quels sont les traits morpho-anatomiques en conditions optimales permettant de prédire la tolérance des espèces herbacées à la sécheresse ? (iv) Quelles formes ont les relations qui existe entre les traits morpho-anatomiques de tolérance en condition optimale et la présence des espèces en cas de sécheresse ? (v) Peut-on prédire les présences des espèces en cas de sécheresse à partir de leurs traits morpho-anatomiques? Nos résultats montrent (1) qu’il est possible de prédire la distribution des espèces sur un gradient d’hydrologie des sols à partir de cinq traits physiologiques de tolérance à la sécheresse. Ces cinq traits sont la photosynthèse nette maximale, la conductance stomatique maximale, le potentiel hydrique du sol au point de flétrissement, la conductance stomatique au point de flétrissement et l’efficacité d’utilisation de l’eau au point de flétrissement. Nous avons montré que (ii) les traits physiologiques de tolérance à la sécheresse sont prédits par les traits morpho-anatomiques en conditions optimales (surface spécifique foliaire, teneur en matière sèche des feuilles, teneur en azote foliaire, longueur spécifique racinaire et surface stomatique). (iii) Les traits morpho-anatomiques seuls ne sont pas de bons prédicteurs de l’hydrologie des espèces et (iv) que la séquence « traits morpho-anatomiques → traits physiologiques → hydrologie des espèces » donne les meilleures prédictions. Cependant, (v) le modèle ne donne pas de prédictions fiables si l’on utilise des traits morpho-anatomiques mesurés en conditions naturelles. Ces résultats confirment, au moins partiellement, l’hypothèse que la distribution des espèces sur un gradient hydrologiques peut être prédite à partir de leurs traits de tolérance à la sécheresse eux-mêmes prédits par leurs traits morpho-anatomiques. En résumé, nous avons utilisé une approche fonctionnelle en construisant un modèle causal prédictif qui nous a permis de nous intéresser aux mécanismes de filtrage environnementaux et plus précisément au rôle de la niche hydrologique des espèces dans l’assemblage des communautés végétales. / Abstract : Species assembly (their presence/absence) in a natural community is the consequence of several filtering mechanisms made by the environment. Among these filters, the abiotic filter selects species able to tolerate local environmental conditions. Variation in water availability in the soil is one of the main environmental gradients according to which plant species are differently distributed. Considering the hypothesis that functional traits and their relationships are hierarchical, habitat preferences of species along environmental gradients should be determined by a combination of hierarchical physiological and morpho-anatomical traits. During this PhD, my overall goal is to identify morphological, anatomical and physiological drought tolerance functional traits that can predict the presence of species along a soil hydrology gradient. More specifically : (i) What are the physiological traits that best reflect drought tolerance? (ii) What are the relationships between morpho-anatomical traits and physiological traits of tolerance? (iii) What are the optimal morpho-anatomical traits for predicting tolerance of herbaceous species to drought? (iv) What forms of relationships exist between optimal morpho-anatomical traits of tolerance and the presence of species in drought condition? (v) Can the presence of species in drought condition be predicted from their morpho-anatomical features? Our results show (1) that it is possible to predict the distribution of species on a soil hydrology gradient from five physiological traits of drought tolerance. These five traits are maximum net photosynthesis, maximum stomatal conductance, water potential of the soil at the wilting point, stomatal conductance at the wilting point, and efficiency of water use at the wilting point. We have shown that (ii) the physiological traits of drought tolerance are predicted by optimal morpho-anatomical traits (leaf area, leaf dry matter content, leaf nitrogen content, root length and stomatal surface). (iii) Morpho-anatomical features alone are not good predictors of species hydrology and (iv) the sequence “morpho-anatomical traits  physiological traits  species hydrology” gives the best predictions. However (v) the model does not provide reliable predictions using morpho-anatomical traits measured under natural conditions. These results confirm, at least partially, the hypothesis that the distribution of species on a hydrological gradient can be predicted from their drought tolerance traits themselves predicted by their morpho-anatomical features. In summary, we used a functional approach by constructing a predictive causal model that allowed us to focus on environmental filtering mechanisms and more specifically on the role of the species hydrological niche in assembling plant communities.

Comment concilier productivité et réduction de l'usage des pesticides ? Le développement de l'oïdium, maladie majeure en viticulture, peut être limité (service de régulation de l'oïdium) par un faible niveau de développement végétatif de la vigne associé à une forte porosité du couvert. Or, de telles caractéristiques limitent également la quantité de rayonnement intercepté par la vigne, et donc la production de biomasse par photosynthèse, et finalement le rendement (service d'approvisionnement). Peut-on augmenter la régulation de l'oïdium sans diminuer le rendement de la vigne ? Autrement dit, existe-t-il une relation de compromis entre ces deux services ? Pour répondre à cette question, deux expérimentations ont été mobilisées : une expérimentation au champ réalisée près de Montpellier de 2010 à 2012 (Syrah), et un réseau de témoins non traités suivis par l'IFV dans la région de Bordeaux de 2007 à 2013. L'analyse des données issues de ces expérimentations a permis de montrer (i) que l'effet des stress hydrique et azoté sur la formation des inflorescences dans les bourgeons latents à la floraison de l'année n-1 détermine 65 à 70 \% du rendement de la vigne lors de l'année n ; (ii) que l'effet du développement végétatif de la vigne sur le développement de l'oïdium n'est significatif que dans le cas d'épidémies de précocité moyenne, dont les premiers symptômes ont été détectés sur feuilles entre la floraison et la fermeture de la grappe. Le développement végétatif de la vigne à la floraison est donc un indicateur pertinent du service de régulation de l'oïdium. Ces résultats ont ensuite permis de confirmer expérimentalement l'hypothèse de l'existence d'un compromis entre rendement de la vigne et régulation de l'oïdium et d'identifier le stress hydrique à la floraison comme un déterminant partagé de ces deux services. Ce dernier point a alors été transcrit dans un modèle simple dans lequel le rendement de la vigne de l'année n dépend principalement de l'année n-1, et le développement végétatif dépend seulement de l'année n. L'analyse des propriétés mathématiques de ce modèle a permis de montrer que la réalisation de compromis favorables entre ces deux services (i.e. un fort niveau des deux services) est possible mais déterminée par l'occurrence de séquences climatiques particulières (une année humide suivie d'une année sèche). Ainsi, les compromis favorables ne peuvent être atteints deux années consécutives et ne sont donc pas stables dans le temps. Les règles de décisions d'application des traitements phytosanitaires pourraient ainsi être adaptées en fonction de la variabilité climatique inter-annuelle et de ses conséquences sur les compromis entre le rendement de la vigne et la régulation des maladies cryptogamiques. / How to combine crop productivity and reduction in pesticide use ? A reduction in plant growth and an increase in crop canopy porosity has been shown to limit the development of the grapevine powdery mildew (powdery mildew regulation service), which is a major disease in viticulture. However, this could also limit grapevine yield through a reduction in light interception and biomass production through photosynthesis. Can regulation of powdery mildew be increased without grapevine yield impairment ? In other words, do these two services trade off ? To address this question, two experiments were used. A field experiment was conducted in Montpellier from 2010 to 2012 on Shiraz, and a network of non-sprayed vineyard plots was monitored by the French Institute of Vine and wine in the Bordeaux region from 2007 to 2013. Data analyses showed that: (i) 65 to 70 \% of grapevine yield in year n were determined by the effect of water and nitrogen stresses on inflorescence formation in the latent buds at flowering in year n-1; (ii) the effect of grapevine vegetative development on powdery mildew depended on epidemic earliness and was significant only when first symptoms were detected on leaves between flowering and bunch closure. Grapevine vegetative development at flowering was therefore a relevant indicator of the powdery mildew regulation service. Based on these results, the hypothesis of a trade-off between grapevine yield and powdery mildew regulation was experimentally confirmed and water stress at flowering was identified as a shared driver of these two services. Then, a simple model was built that accounted for the effect of water stress at flowering on the two services, where grapevine yield depended mostly on year n-1 and grapevine vegetative development depended only on year n conditions. Analysis of the model's mathematical properties showed that "win-win" scenarios (high level of both services) did exist and were reached when specific climatic sequences occured (a wet year followed by a dry year). The "win-win" scenarios could not be reached two consecutive years and were therefore temporally unstable. Decision rules for pesticides application may be adapted in function of the inter-annual climatic variability and its effect on the trade-off between grapevine yield and regulation powdery mildew.

Brassica napus est une des cultures oléagineuse majeure dans le monde. En raison de sa faible efficacité d’utilisation de l’azote (NUE) comparée aux autres grandes cultures, la gestion de cette ressource présente un objectif écologique et économique majeur pour cette culture. La remobilisation des nutriments des organes sources vers les organes puits est une composante de la NUE qui se déroule durant la sénescence et qui est associée aux processus de recyclages métaboliques et à des modifications de la structure foliaire. L’objectif de cette thèse était de comprendre et de quantifier ces modifications structurales afin d’évaluer à travers ces processus les capacités de remobilisation du colza en fonction de son génotype et de son statut nutritionnel (eau et azote). La structure foliaire a été étudiée grâce à la relaxométrie RMN qui donne accès au statut et à la distribution de l’eau au niveau cellulaire. Ces travaux de thèse ont mis en évidence que la distribution des temps de relaxation transversale (T2) dépend non seulement de la structure cellulaire, mais aussi de l’organisation tissulaire. Cette étude a aussi mis en évidence le processus d’élargissement cellulaire et d’hydratation pendant la sénescence, spécifiquement dans le parenchyme palissadique. Il a été également démontré que le signal RMN reflète la déstructuration progressive se déroulant durant la sénescence au niveau subcellulaire et est un marqueur de sénescence précis permettant de suivre le développement de la feuille. De plus, le statut nutritionnel de la plante modifié par les carences azotées ou le stress hydrique, impacte grandement la sénescence séquentielle et les conséquences en termes d’efficacité de la remobilisation peuvent être suivies par RMN. Ce travail a permis de renforcer les connaissances sur la structure et le fonctionnement de la feuille au niveau tissulaire et cellulaire. De plus, il a été démontré que le signal de relaxométrie RMN donne accès à des informations sur la structure foliaire inaccessible par des méthodes courantes. Une des principales applications de ce travail serait le phénotypage, particulièrement la sélection de génotypes caractérisés par une forte efficacité de remobilisation en particulier en cas de carence azoté ou de stress hydrique. / Brassica napus is one of the major oil crops of the world. Due to its low NUE (Nitrogen Use Efficiency) compared to other species, Nitrogen management presents a major economic and environmental goal for improvement of that crop production. As a component of NUE, nutrient remobilization from source to sink tissues takes place mainly during the leaf senescence and is associated to metabolic recycling processes and modification of the cellular organization and structure. The aim of this work was therefore to understand and estimate the amplitude of these structural modifications with the objective to appreciate through these processes remobilization performance according to oilseed rape genotypes and nutritional status in terms of nitrogen and water supply. The leaf structure was investigated through NMR relaxometry, providing access to cellular water status and distribution. The present work demonstrated that the transverse relaxation time (T2) distribution depends on both leaf tissue structure and cellular compartmentalization. The study revealed a process of cell enlargement and hydration during leaf senescence, specifically in the palisade parenchyma and showed that the T2 relaxation time was able to discriminate parenchyma tissues at an early phase of senescence induction. Moreover, the NMR relaxometry signal was shown to reflect specific chronological loss of sub-cellular structuring all along the senescence process progression and was demonstrated to be an accurate non-invasive monitoring method of leaf development. Finally, plant nutrition status experienced through nitrogen and water availability limitation has been demonstrated to strongly affect regular sequential leaf senescence. Consequences on remobilization efficiency by stress conditions have been also assessed through the NMR signal. This work has improved the understanding of leaf structure and functioning at the cell and tissue levels after the onset and during the progression of senescence. Moreover, it was demonstrated that NMR relaxometry provides access to leaf structural information that are not accessible with currently used techniques for plant structural investigations. One of the main applications would be for plant phenotyping, especially for selecting genotypes with higher nutrient remobilization efficiency especially under environmental stresses like nitrogen and water limitations for sustainable oil and protein production.

Salinity continues to be one of the world’s most serious environmental problems in agriculture. The increasing world population and urbanization are forcing farmers to utilize marginal lands as well as poor quality water. One of the strategies in dealing with salinity is growing salt tolerant plants and there has been increased need to understand the effects of salinity on crops. Owing to its high nutritive value and wide adaptability to diverse environments, amaranth is considered a promising crop for marginal lands and semiarid regions. The objective of the study was to investigate the response of amaranth to salinity stress and evaluate stress amelioration by calcium and seed priming. Salinity tolerance during germination and early seedling growth was examined for six genotypes of amaranth (Amaranthus species) at different salt concentrations ranging from 0 to 200 mM NaCl or Na2SO4. Enhancement of germination was observed at 25 mM, while increasing salt concentrations reduced the germination percentage as well as germination rate. A.tricolor and Accession ’83 were able to germinate in 200 mM NaCl while there was no germination at 200 mM Na2SO4 in all the genotypes. Overall, Accession ’83 was the most resistant and A. hybridus the most sensitive genotype, particularly at high salt concentrations. Inhibition of germination was greater in Na2SO4 than in NaCl salinity treatments. Amaranth was more salt tolerant at germination than at seedling growth. Seedling emergence, survival and growth were reduced by salinity and at much lower concentrations than at seed germination. Differences in salt tolerance were noted among the genotypes. Salinity stress was initiated at different growth stages (cotyledon stage, 2-leaf stage and 4-leaf stage) in order to determine whether tolerance of amaranth differs with the stage of development. The treatment either continued until termination of the experiment or for 14 days at each stage. Amaranth plants were less sensitive to salinity when the stress was initiated at the 4-leaf stage. Lower salt concentrations had less detrimental effects than higher concentrations when applied at the cotyledon stage. Application of low salt concentration at cotyledon stage for 14 days did not have any effect on plant growth. The results indicate that it is feasible to use saline water for growing amaranth with minimum yield losses if salt concentration, duration of exposure and time of salinization are carefully managed. Differences in salinity tolerance among amaranth genotypes were analyzed in terms of plant survival, growth, gas exchange, water use and leaf anatomical changes. A. hypochondriacus and A. cruentus showed greater tolerance to salinity since they survived in 200 mM NaCl treatment and the reduction in growth at 50 and 100 mM was lower than that of A. tricolor and Accession ’83. A. hypochondriacus and A. cruentus were more efficient water users and partitioned photosynthates towards shoot growth as opposed to the other two genotypes. Photosynthetic rate, stomatal conductance, stomatal density and apertures were reduced by salinity but were higher in A. tricolor than in A. cruentus. Salinity resulted in A. cruentus developing thicker leaves compared to A. tricolor. Productivity on saline soils can be increased by growing genotypes more tolerant to salinity. The interactive effect of salinity and water stress on amaranth plant growth was evaluated. It was found that the reduction in shoot growth was greater in plants submitted to water stress than in those submitted to salt or salt + water stress. Water use efficiency was increased while leaf water and osmotic potentials were reduced by the salinity stress treatments. In drying soil plants previously salinized had a greater degree of osmotic adjustment, so that plants were able to continue growth for a longer period compared to water stressed plants. The effect of calcium in ameliorating salt stress was investigated. Supplementary calcium, either as CaSO4 or CaCl2 ameliorated the negative effects of salinity on growth, gas exchange, membrane permeability and mineral uptake. In a separate experiment it was shown that it is feasible to mitigate the adverse effects of salinity on amaranth seed germination, seedling survival and growth by seed priming and that the positive effect of priming persisted to vegetative growth stage. Priming with CaSO4 + NaCl showed a greater positive response than priming with the individual salts. / Thesis (PhD (Plant Production andSoil Science))--University of Pretoria, 2007. / Plant Production and Soil Science / unrestricted

O amendoim (Arachis hypogaea L.) é um grão muito apreciado em todo o mundo, sendo cultivado em vários países desenvolvidos e em desenvolvimento. A planta é uma oleaginosa com alto valor nutricional e rica em compostos bioativos, cultivada largamente em zonas de clima semiárido, onde prevalece a seca, que pode afetar a produção e a composição dos grãos. O objetivo deste trabalho foi avaliar a composição química, atividade antioxidante, compostos fenólicos, tocoferóis e ácidos graxos de genótipos de amendoim contrastantes quanto à adaptação a ambientes com limitação hídrica, bem como definir quais atributos são capazes de caracterizar esses genótipos. Os genótipos utilizados foram oriundos do programa de melhoramento genético de amendoim da Embrapa Algodão (Campina Grande - PB), os quais são adaptados ao estresse hídrico. Foram analisados grãos com e sem película, uma vez que seu consumo pode ocorrer de ambas as formas. Para os grãos sem a película a caracterização da fração oleosa foi realizada por meio da identificação e quantificação dos ácidos graxos e tocoferóis, enquanto que a avaliação química da fração fenólica foi feita por espectrometria de massas de alta resolução (LC-ESI-LTQ-Orbitrap-MS). A atividade antioxidante foi determinada por meio da desativação de espécies reativas de oxigênio (superóxido, ácido hipocloroso e peroxila) e do método on-line (HPLC-ABTS). Os resultados da caracterização da fração oleosa e fenólica dos grãos despeliculados foram ainda avaliados por análise multivariada para se definir quais atributos eram capazes de caracterizar os diferentes genótipos de amendoim. Para os grãos com a película foi realizada a caracterização química dos polifenóis por LC-ESI-LTQ-Orbitrap-MS, e a avaliação da atividade antioxidante pelo sequestro dos radicais livres DPPH e ABTS, além da análise multivariada dos resultados. De maneira geral, os genótipos tolerantes à seca foram os que apresentaram maior capacidade antioxidante. Os genótipos de amendoim avaliados apresentaram de 36 a 58% de ácidos graxos monoinsaturados em sua constituição, e relação oleico/linoleico mais elavada para os genótipos rasteiros. Foram também encontradas quantidades significativas de tocoferóis nos materiais analisados. O ácido p-cumárico, ácido cafeíco e a rutina foram identificados e quantificados por cromatografia líquida de alta resolução. Foram identificados, por meio da técnica de espectrometria de massas de alta resolução, 26 compostos fenólicos nos genótipos de amendoim despeliculados. Os grãos com película apresentaram perfil fenólico mais complexo, sendo identificados 58 compostos pertencentes a cinco classes distintas. Os isômeros do ácido coutárico foram os principais polifenóis, seguidos pela isorhamnetina-3-O-rutinosideo e os isômeros de ácido cumárico. De acordo com os resultados obtidos e a literatura, foram identificados 9 compostos nunca relatados em amendoim. As variáveis analisadas neste estudo mostraram ser possível o agrupamento dos genótipos de amendoim contrastantes quanto à adaptação aos ambientes com restrição hídrica. / Peanuts (Arachis hypogaea L.) are a widely appreciated grains throughout the world and it has been grown both in developed and developing countries. The plant is an oleaginous with high nutritional value and rich in bioactive compounds that has been cultivated in semi-arid zones - where drought prevails and it affects grain yield and composition. Thus, the aim of this work was in evaluating the chemical composition, antioxidant activity, phenolic compounds, tocopherols and fatty acids of contrasting peanut genotypes in relation to the adaptation to water limitation environments, as well as defining which attributes are able to characterize these genotypes. The adapted peanuts to water stress used here came from the breeding program of Embrapa Algodão (Campina Grande - PB). Grains with and without skin were analyzed, since their consumption can occur in both forms. In relation to the grains without the skin, the characterization of the oily fraction was made through the identification and quantification of the fatty acids and tocoferols, whereas the chemical evaluation of the phenolic fraction was performed by high-resolution mass spectrometry (LC-ESI-LTQ-Orbitrap-MS). The antioxidant activity was determined by reactive oxygen species deactivation (superoxide, hypochlorous acid and peroxyl) and on-line method (HPLC-ABTS). The results obtained through characterization of the oily and phenolic fraction of the grains without skin were further evaluated by multivariate analysis to determine which attributes were able to characterize the different peanut genotypes. In relation to the grains with skin, it was made the chemical characterization of the polyphenols by LC-ESI-LTQ-Orbitrap-MS and the evaluation of the antioxidant activity by the sequestration of the radicals DPPH and ABTS; besides, it was made the multivariate analysis of the results. In general, the samples tolerant to drought were the ones that presented greater antioxidant capacity than the others. The evaluated peanut genotypes presented 36 to 58% of monounsaturated fatty acids in relation to the total lipids in its constitution and showed oleic/linoleic ratio classified in normal and mid-oleic, which is a higher ratio for non-drought tolerant genotypes. Significant amounts of tocopherols were also found in the analyzed materials. p-coumaric acid, caffeic acid and rutin were identified and quantified by high-performance liquid chromatography. Twenty-six phenolic compounds were also identified in peanuts without skin using the high-resolution mass spectrometry technique. The peanuts with skin showed a more complex phenolic characteristc by being identified 58 compounds belonging to five different classes. The isomers of coutaric acid were the major polyphenols, followed by isorhamnetin-3-O-rutinoside and the isomers of coumaric acid. According to the results obtained and the literature, it is been identified 9 new compounds which were never found in peanuts. The variables analyzed in this study showed that it is possible to group contrasting genotypes peanuts as to drought tolerance.

Submitted by Luis Ricardo Andrade da Silva (lrasilva@uefs.br) on 2015-12-02T20:10:10Z No. of bitstreams: 1 v.final DISSERTA??O B?RBARA PAULA DOS SANTOS BORGES DOS SANTOS BORGES.pdf: 1253496 bytes, checksum: b385afcd4779d54bd2a324ab4f1f5b5f (MD5) / Made available in DSpace on 2015-12-02T20:10:10Z (GMT). No. of bitstreams: 1 v.final DISSERTA??O B?RBARA PAULA DOS SANTOS BORGES DOS SANTOS BORGES.pdf: 1253496 bytes, checksum: b385afcd4779d54bd2a324ab4f1f5b5f (MD5) Previous issue date: 2015-08-26 / Funda??o de Amparo ? Pesquisa do Estado da Bahia - FAPEB / Vellozia sincorana Ayensu & SMITHis endemic of Rupestres Fields of Chapada Diamantina, popularly known as Candomb?. This species has a highly flammable resin, and the stem used to ignite wood stoves and roots to produce incense. Candomb? presents few studies in the literature, there are no studies of propagation of the species. This study aimed to develop in vitro multiplication protocol of V. sincorana, analyzing the behavior of in vitro shoots subjected to stress, and its influence on multiplication. They were used as explants in vitro shoots obtained, inoculated with concentrations of BAP (0.0; 2.22; 4.44 ?M), CIN (0.0; 2.32; 4.64 ?M) and IBA (0.0; 1.48 ?M) in MS ? medium supplemented with 87.64 mM sucrose, 1g.L-1activated carbon, and 0.7% agar (basic medium). Subsequently, it tested concentrations of cytokinins BAP or KIN (0.0; 5.0; 10.0; 15.0; 20.0 ?M). In experiments with thermal stress, flame shoots were exposed for different periods (0.0; 2.0; 4.0; 6.0; 8.0; 10 seconds), and the next tested whether the periods (0.0; 4.5; 6.0; 7.5; 9.0 min) exposure of the shoots 105 ? 1 ? C in sterilize. For drought stress basic medium was agar supplemented with different concentrations (7.0; 14.0; 21.0; 28.0 g) and the following experiment different sucrose concentrations (87.64; 175.28; 262. 92; 350.56 mM). The KIN showed greater efficacy in the multiplication in relation to BAP. The highest average for number of shoots and responsive% explants were in the periods 6, 8 or 10 seconds, being observed tolerance to water and thermal stress. / Vellozia sincorana AYENSU & SMITH ? end?mica dos Campos Rupestres da Chapada Diamantina, conhecida popularmente como Candomb?. Essa esp?cie possui resina altamente inflam?vel, sendo o caule utilizado para acender fog?es a lenha e as ra?zes para produzir incenso. O Candomb? apresenta poucos trabalhos na literatura, n?o havendo estudos de propaga??o da esp?cie. Esse trabalho teve como objetivo desenvolver protocolo de multiplica??o in vitro de V. sincorana, analisando o comportamento dos brotos in vitro submetidos ao estresse, e sua influ?ncia na multiplica??o. Foram utilizados como explantes brotos obtidos in vitro, inoculados em concentra??es de BAP (0,0; 2,22; 4,44 ?M), CIN (0,0; 2,32; 4,64 ?M) e AIB (0,0; 1,48 ?M) em meio MS ?suplementado com 87,64mM de sacarose, 1g.L-1 de carv?o ativado, e0,7% de ?gar (meio b?sico).No experimento seguinte, testou-se concentra??es das citocininas BAP ou CIN (0,0; 5,0; 10,0; 15,0; 20,0 ?M). Nos experimentos com estresse t?rmico, os brotos foram expostos a flambagem por diferentes per?odos (0, 2, 4, 6, 8; 10 segundos), e no seguinte testou-se os per?odos (0,0, 4,5, 6,0, 7,5; 9,0 min.) de exposi??o dos brotos a 105?1?C, em estufa. Para estresse h?drico o meio b?sico foi suplementado com diferentes concentra??es de ?gar (7,0, 14,0, 21,0, 28,0 g) e no experimento seguinte diversas concentra??es de sacarose (87,64, 175,28, 262,92; 350,56 mM).O CIN apresentou maior efic?cia na multiplica??o, em rela??o ao BAP. As maiores m?dias para n?mero de brotos e % explantes responsivos foram nos per?odos 6, 8 e 10 segundos, sendo observada toler?ncia aos estresses h?drico e t?rmico.

Para que ocorra a indução floral em citros, as plantas necessitam passar por algum tipo de estresse hídrico ou térmico (baixas temperaturas). Apesar do estresse hídrico ser importante para o florescimento, condições extremas deste tipo de estresse podem prejudicar o desenvolvimento e a fixação dos frutos na planta posteriormente ao período de florescimento. Neste sentido, a redução da fração de área molhada do solo pode também ser uma fonte de estresses hídrico nas plantas. Dessa forma, o presente trabalho tem como objetivo estudar o efeito do estresse hídrico e da fração de área molhada (100% e 12,5%) nas relações hídricas da laranjeira Valência, sob dois tipos solo e dois porta-enxertos. O experimento foi conduzido na área de pesquisa do Departamento de Engenharia de Biossistemas na Escola Superior de Agricultura Luiz de Queiroz (ESALQ/USP) em ambiente protegido. Foi utilizado o delineamento em esquema fatorial 2 x 2 x 2 x 2 com os tratamentos dispostos em faixas, totalizando 16 tratamentos, constituídos da combinação de dois tipos de solos (argiloso e franco-arenoso), dois porta-enxertos (limoeiro Cravo e citrumelo Swingle), duas frações de área molhada (100% e 12,5%) e dois níveis de deficiência hídrica: 1) Estresse Hídrico Contínuo (suspensão da irrigação por 30 dias) 2) Estresse Hídrico Intermitente (sub-lâmina) - aplicação de 30% da ET0. As plantas foram conduzidas em caixas de 500 L internamente divididas em compartimentos. O inicio do experimento de estresse hídrico consistiu em realizar a irrigação do volume total do solo, elevando-o a capacidade de campo, sendo suspensas as irrigações durante o período de avaliação, sendo após realizado o acompanhamento diário do consumo hídrico em cada compartimento das caixas. Amostrou-se o sistema radicular das plantas, para cada compartimento existente para averiguar a existência de adaptação radicular em função da restrição de área molhada. Determinou-se simultaneamente a transpiração de todas as plantas através de sondas de dissipação térmica, o conteúdo de água no solo, o crescimento das plantas (área foliar e diâmetro de caule), o potencial de água na folha e a temperatura foliar. A extração de água no solo após 6 meses de irrigação localizada indica que o sistema radicular na zona irrigada consegue redistribuir parte da água absorvida, pelo sistema radicular da planta que se encontra na área seca, mantendo-o vivo. Observa-se que no solo argiloso as plantas apresentaram um maior comprimento total de raízes do que no solo arenoso. A média do módulo do potencial da água na folha das plantas sob condição simulada de irrigação por gotejamento, foi 31,5% maior quando comparado às plantas com 100% de solo molhado (-1,085 MPa e -0,7435 MPa). Em termos de área foliar, o estresse contínuo promoveu uma maior desfolha das plantas, sendo significativa a diferença entre os tipos de solo, as condições de estresses e a interação tipo de solo e porta-enxertos. Treze dias após a imposição dos estresses, a temperatura foliar, nos períodos de maior demanda atmosférica (14:00hs) tende a ser maior do que a temperatura do ar. Independente do tipo de estresse, para solo arenoso a transpiração diminui quanto se impõe a redução de área molhada (gotejamento). Esperava-se que os tipos de estresse hídrico impostos apresentassem uma diferenciação de consumo hídrico nas plantas, no período de retomada da irrigação, sendo o estresse intermitente o que deveria apresentar o maior consumo hídrico; nos resultados obtidos não ficou muito clara e estabilizada esta tendência, apesar do nível de desfolha e o potencial de água nas folhas confirmaram as hipóteses inicialmente formuladas. Existe a possibilidade de que o método de dissipação térmica tenha sofrido influência significativa da desfolha no gradiente térmico natural, o que pode ter ocasionado imprecisão nos dados coletados e resultado inconsistência nos fluxos de seiva calculados neste período de baixo índice de área foliar. / In order to present floral induction, citrus plants need to undergo some type of thermal (low temperature) or water stresses. However, despite a certain level of water stress is important for the flowering, excessive water stress can impair the development and fruit set in the plant. In this sense, to reduce the fraction of wetted area of the soil can also be a source of water stress in plants. This paper aims to study the effect of water stress and the fraction of wetted area (100% and 12.5%) in Valencia orange tree transpiration under two soil types and two rootstocks. The experiment was conducted at the Department of Biosystems Engineering at the School of Agriculture \"Luiz de Queiroz\" (ESALQ / USP) in a protected environment. It was used a randomized design in a factorial 2 x 2 x 2 x 2 with treatments arranged in strips, totaling 16 treatments combinations, consisting of two soil types (clay and sandy loam), two-door grafts (Rangpur lime and citrumelo \'Swingle\'), two fractions of wetted area (100% and 12,5%) and two levels of water stress: 1) Continuous Stress (suspension of irrigation for 30 days) 2) Intermittent Stress (deficit irrigation: 30% ET0). The plants were conducted in 500 L boxes divided into compartments inside. At the beginning of the water stress experiment, soil moisture was set to field capacity. Irrigation was suspended during the evaluation period, and it was monitoring every day the water consumption in each compartment boxes. Root systems of plants were sampled for each compartment to determine total length of roots in the soil. It were determined the individual transpiration of each plant using thermal dissipation probes (sap flow / Granier), the water content in soil, the plant growth (leaf area and stem diameter), the leaf water potential and leaf temperature. The extraction of water in the soil after 6 months of drip irrigation indicates that the root system in the irrigated area redistribute some of the absorbed water to the root system that is in the dry area, keeping it alive waiting for the raining period. It was observed for the clay soil a greater total length of roots compared to the sandy soil. The mean of leaf water potential for plants under simulated drip irrigation conditions (12.5 % wetted area) was 31,5% higher compared to plants with 100% of wetted area (-1,085 MPa and -0,7435 MPa). In terms of leaf area, the continuous stress promoted a greater leaf loss of plants, with a significant difference between soil types, stress types and the interaction of soil type and rootstock. Thirteen days after the imposition of the water stresses, leaf temperature at around 2:00 pm tends to be higher than air temperature. For sandy soil, independent of the water stress type, transpiration decreases as the wetted area is reduced (drip). It was expected for the water stress types imposed, a differentiation of plants water consumption after resuming irrigation for fruit set, being the intermittent stress the greatest water consumption treatment. The results obtained are unclear and non-stabilized for this trend, although leaf losses and leaf water potential confirmed the hypothesis initially formulated. There is a possibility that thermal dissipation probles suffered significant influence of leaf losses on the natural thermal gradient, which may have caused inaccuracies in the collected data, resulting inconsistent values of sap flow calculated for this period of low leaf area index.

Tesis por compendio / [EN] Pepper is a vegetable of extraordinary economic and social importance in our country. Unfortunately, the persistent exploitation of the land, the monoculture and the intensification of production processes, lead to the development of soil diseases. This coupled with the abiotic stress, mainly the salinity of waters and soil, suboptimal temperatures and water stress, can induce the appearance of physiological disorders in peppers as the Blossom-end rot (BER) and cracking or cracked, induce plant senescence and decrease not only production, but also the quality of the product. Salinity and water shortages are two among the biggest environmental problems that crops have to face in the Mediterranean area. A way to overcome the stresses under the prism of an ecological or integrated crop management, is the use of grafted plants as adaptation strategy. Although there has been remarkable progress in this technique (mainly in tomato, melon, watermelon), in the cultivation of pepper use remains rare. In this Doctoral thesis several pepper genotypes have been selected through different physiological parameters which indicate tolerance to salt and water stress. Commercial cultivars were grafted onto the selected genotypes and were grown under water stress, salinity and control conditions studying several physiological, agronomic responses and the interaction rootstock/scion. The results obtained concluded that genotypes selected and used as rootstocks improved commercial varieties to salt and water stress tolerance, both in terms of performance (commercial production) compared to other commercial characters and variety without grafting. Different physiological mechanisms explain the tolerance to stress, such as the ability to maintain the water potential through an osmotic adjustment, stimulation of the antioxidant system, exclusion or retention of toxic ions (Na+ and Cl-) in saline in the roots and the maintenance of photosynthesis which allows to maintain the metabolic functions of grafted plants and production. / [ES] El pimiento es una hortaliza de extraordinaria importancia económica y social en nuestro país. Lamentablemente, la persistente explotación del suelo, el monocultivo y la intensificación de los procesos de producción, conducen al desarrollo de enfermedades del suelo. Esto unido a los estreses abióticos, principalmente la salinidad de las aguas y del suelo, temperaturas subóptimas y estrés hídrico, puede inducir la aparición de fisiopatias en el pimiento como el Blossom-end rot (BER) y cracking o rajado, inducir senescencia vegetal y disminuir no solo la producción, sino también la calidad del producto. La salinidad y la escasez de agua son unos los mayores problemas medio ambientales a los que tienen que hacer frente los cultivos en el área Mediterránea. Un modo de sortear los estreses bajo el prisma de un manejo integrado o ecológico del cultivo, es la utilización de plantas injertadas como estrategia de adaptación. Aunque se ha producido un notable avance en esta técnica (principalmente en tomate, melón, sandía), en el cultivo del pimiento su utilización es poco frecuente aun. En esta Tesis Doctoral se han seleccionado mediante parámetros fisiológicos diferentes genotipos de pimiento tolerantes al estrés salino e hídrico. Los genotipos seleccionados fueron validados como patrones tolerantes a condiciones de estrés hídrico y salino injertados sobre una variedad comercial mediante el estudio de las respuestas fisiológicas, agronómicas y de la interacción patrón/variedad en ambas condiciones de estrés. De los resultados obtenidos se concluye que los genotipos seleccionados y utilizados como patrones mejoraron la tolerancia de las variedades comerciales a la salinidad, en términos de rendimiento (producción comercial) de frutos comparando con otros patrones comerciales y la variedad sin injertar. Diferentes mecanismos fisiológicos explican la tolerancia al estrés, como la capacidad de mantener el potencial hídrico mediante un ajuste osmótico, estimulación del sistema antioxidante, exclusión o retención de los iones tóxicos salinos (Na+ y Cl-) en las raíces y el mantenimiento de la fotosíntesis que permite mantener las funciones metabólicas de las plantas injertadas y la producción. / [CA] El pimentó és una hortalissa d'extraordinària importància econòmica i social al nostre país. Lamentablement, la persistent explotació del sòl, el monocultiu i la intensificació dels processos de producció, conduïxen al desenrotllament de malalties del sòl. Açò unit als estressos abiòtics, principalment la salinitat de les aigües i del sòl, temperatures subòptimes i estrés hídric, pot induir l'aparició de fisiopaties en el pimentó com el Blossom-end rot (BER) i cracking, induir senescència vegetal i disminuir no sols la producció, sinó també la qualitat del producte. La salinitat i l'escassetat d'aigua són uns els majors problemes mitjà ambientals als que han de fer front els cultius en l'àrea Mediterrània. Una manera de sortejar els estressos davall el prisma d'un maneig integrat o ecològic del cultiu, és la utilització de plantes empeltades com a estratègia d'adaptació. Encara que s'ha produït un notable avanç en esta técnica (principalment en tomaca, meló, meló d'alger), en el cultiu del pimentó la seua utilització és poc freqüent. En esta Tesi Doctoral s'han seleccionat per mitjà de paràmetres fisiològics diferents genotips de pimentó tolerants a l'estrés salí i hídric. Els genotips seleccionats van ser validats com a patrons tolerants a condicions d'estrés hídric i salí empeltats sobre una varietat comercial per mitjà de l'estudi de les respostes fisiològiques, agronòmiques i de la interacció patrón/variedad en ambdós condicions d'estrés. Dels resultats obtinguts es conclou que els genotips seleccionats i utilitzats com a patrons van millorar la tolerància de les varietats comercials a la salinitat, tant en termes de rendiment (producció comercial) de fruits comparant amb altres patrons comercials i la varietat sense empeltar. Diferents mecanismes fisiològics expliquen la tolerància a l'estrés, com la capacitat de mantindre el potencial hídric per mitjà d'un ajust osmòtic, estimulació del sistema antioxidant, exclusió o retenció dels ions tòxics salins (Na+ i Cl-) en les arrels i el manteniment de la fotosíntesi que permet mantindre les funcions metabòliques de les plantes empeltades i la producció. / Penella Casañ, C. (2015). SCREENING PEPPER GENOTYPES TO OBTAIN TOLERANT ROOTSTOCKS TO SALT AND WATER STRESS: PHYSIOLOGICAL AND AGRONOMICAL RESPONSES OF THE GRAFTED PLANTS [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58767 / Premios Extraordinarios de tesis doctorales / Compendio

Tesis por compendio / [ES] El pimiento es un cultivo muy importante a nivel mundial, pero es sensible a la falta de agua y a la salinidad. No obstante, se puede mejorar la tolerancia mediante la técnica del injerto. El Instituto Valenciano de Investigaciones Agrarias y la Universidad Politécnica de Valencia han realizado estudios previos para seleccionar accesiones de pimiento tolerantes a ambos estreses, utilizando después una selección de ellos como portainjertos para estudiar los mecanismos fisiológicos de tolerancia y aumentar la rentabilidad de su producción. Sin embargo, después de todos estos estudios, la información disponible es limitada. En este sentido, los objetivos que se han planteado en esta tesis doctoral fueron: i) seleccionar nuevas accesiones tolerantes de pimiento a la salinidad y escasez de agua, para aumentar la disponibilidad de genotipos tolerantes y usarlos en futuros programas de mejora, con el objetivo final de obtener nuevos portainjertos con una tolerancia mejorada; ii) identificar a corto plazo los mecanismos fisiológicos de tolerancia al estrés hídrico de una accesión tolerante (A25) usada como portainjerto; iii) identificar a corto plazo los mecanismos fisiológicos de tolerancia a la salinidad de un nuevo portainjerto híbrido tolerante (NIBER®); iv) encontrar los principales mecanismos moleculares de tolerancia a la salinidad de una accesión tolerante (A25) respecto a una sensible (A6) desde el punto de vista transcriptómico. Una vez realizados estos ensayos, en primer lugar, pudimos relacionar positivamente la capacidad fotosintética y el mantenimiento del crecimiento en plantas tolerantes a estrés hídrico y salino, tanto sin injertar como injertadas; de hecho, basándonos principalmente en esta relación, seleccionamos las accesiones A34 y A31 como tolerantes a estrés salino e hídrico, respectivamente. Además, demostramos que el papel principal de la prolina en los estreses estudiados no está ligado a la bajada de potencial osmótico; sin embargo, se identificaron funciones protectoras de este aminoácido que, junto a otras moléculas antioxidantes como los fenoles, contribuyen en el pimiento a aumentar la tolerancia. Igualmente importante es el peróxido de hidrógeno, que se relacionó con la capacidad antioxidante en pimiento, funcionando como molécula señalizadora en estrés salino. Asimismo, la bajada de ácido abscísico y la modificación de la expresión de genes relacionados han sido también relevantes en condiciones de estrés salino para mantener la apertura estomática y, por consiguiente, el crecimiento en plantas sin injertar e injertadas sobre portainjertos tolerantes. Se demostró también que la limitación del transporte de Na+ a hojas, así como el transporte y acumulación eficiente de K+ en raíces y hojas, son esenciales para alcanzar la homeostasis iónica y por tanto la tolerancia en pimientos injertados sobre portainjertos tolerantes. Para finalizar, el estudio de las rutas moleculares fue una herramienta útil para confirmar el comportamiento fisiológico y agronómico de una accesión de pimiento previamente clasificada como tolerante a la salinidad, descubriendo además nuevos mecanismos no referenciados hasta el momento. Los genes diferencialmente expresados encontrados estaban relacionados con la señalización hormonal, el crecimiento y desarrollo de las plantas, la fotoprotección, la regulación de los transportadores de iones y la detoxificación de ROS. / [CA] El pimentó és un cultiu molt important mundialment, però és sensible a la falta d'aigua i la salinitat. No obstant això, es pot millorar la tolerància mitjançant la tècnica de l'empelt. L'Institut Valencià d'Investigacions Agràries i la Universitat Politècnica de València han fet estudis previs per a seleccionar accessions de pimentó tolerants a tots dos estressos i a continuació, una selecció d'entre elles es va utilitzar per a estudiar els mecanismes fisiològics de tolerància i augmentar la rendibilitat de la seua producció. No obstant això, després de tots aquests experiments, la informació encara és limitada. En aquest sentit, els objectius que s'han plantejat en aquesta tesi doctoral van ser: i) seleccionar noves accessions tolerants de pimentó a la salinitat i la falta d'aigua, per a augmentar la disponibilitat de genotips tolerants i usar-los en futurs programes de millora, amb l'objectiu final d'obtindre nous portaempelts amb una tolerància millorada; ii) identificar a curt termini els mecanismes fisiològics de tolerància a l'estrès hídric d'una accessió tolerant (A25) usada com portaempelt; iii) identificar a curt termini els mecanismes fisiològics de tolerància a la salinitat d'un nou portaempelt híbrid tolerant (NIBER®); iv) trobar els principals mecanismes moleculars de tolerància a la salinitat d'una accessió tolerant (A25) respecte a una sensible (A6) des d'un punt de vista de la transcriptòmica. Després de realitzar aquests assajos, en primer lloc, vam poder relacionar positivament la capacitat fotosintètica i el manteniment del creixement en plantes tolerants a l'estrès hídric i salí, tant sense empeltar com empeltades; de fet, basant-nos principalment en aquesta relació, vam seleccionar les accessions A34 i A31 com tolerants a l'estrès salí i hídric, respectivament. A més a més, vam demostrar que el paper principal de la prolina en els estressos estudiats no està lligat a la baixada de potencial osmòtic; en canvi, es van identificar diferents funcions protectores d'aquest aminoàcid, que, junt a altres molècules antioxidants com els fenols, contribueixen en el pimentó a combatre'ls. Igualment important és el peròxid d'hidrogen, que es va relacionar amb la capacitat antioxidant del pimentó, funcionant com a molècula senyalitzadora a l'estrès salí. Així mateix, la baixada d'àcid abscísic i la modificació de l'expressió de gens relacionats de la seua senyalització han sigut també rellevants en condicions d'estrès salí per a mantindre l'obertura estomàtica i per tant el creixement en plantes sense empeltar i empeltades amb portaempelts tolerants. Es va demostrar també que la limitació del transport de Na+ a les fulles, així com el transport i l'acumulació eficient de K+ a les arrels i les fulles, són essencials per a aconseguir l'homeòstasi iònica i per tant la tolerància en pimentons empeltats damunt portaempelts tolerants. Per concloure, l'estudi de les rutes moleculars va ser un instrument útil per a confirmar el comportament fisiològic i agronòmic d'una accessió de pimentó prèviament classificada com a tolerant, descobrint a més nous mecanismes no trobats fins ara. Els gens diferencialment expressats trobats estaven relacionats amb la senyalització hormonal, el creixement i el desenvolupament de les plantes, la fotoprotecció, la regulació dels transportadors de ions i la detoxificació de ROS. / [EN] Pepper culture is economically very important worldwide, although it is very sensitive to suboptimal conditions of water and high salinity. However, the tolerance to these stresses can be improved by the grafting technique. Previous studies of the Valencian Institute for Agricultural Research and the Polytechnic University of Valencia have been conducted to select pepper accessions that showed tolerance to both stresses, after which a further selection of them was used as rootstocks to find physiological mechanisms of tolerance and to increase its agronomic profit. However, after all these studies, the available information in this regard is still scarce. Therefore, the objectives of this thesis were to: i) screen new tolerant pepper accessions under high salt concentrations and suboptimal water conditions, to increase the availability of tolerant genotypes to be used in future breeding programmes, with the final aim of obtaining new and improved tolerant rootstocks; ii) identify the short-term physiological mechanisms of water stress tolerance of a tolerant accession (A25) used as a rootstock; iii) identify the physiological mechanisms of short-term tolerance to salinity of a new tolerant hybrid rootstock (NIBER®); and iv) find the main molecular pathways of salinity tolerance of a tolerant accession (A25) compared to a sensitive one (A6) by a transcriptomic approach. After conducting these studies, we firstly found a positive relationship between photosynthetic capacity and growth maintenance in plants that were tolerant to water or salt stress, both grafted or ungrafted; indeed, based mainly on this relationship, we selected accessions A34 and A31 as tolerant to salt and water stress, respectively. In addition, we were able to demonstrate that the main role of proline under salinity and water scarcity is not linked herein to the drop in osmotic potential; on the contrary, we identified different protective roles that, together with other antioxidant protective molecules such as phenols, contribute to the tolerance of pepper plants to these environmental stresses. Moreover, hydrogen peroxide, a reactive oxygen species, was found to play important roles in the antioxidant capacity of pepper, working as a signalling molecule under salinity stress. Furthermore, the drop in abscisic acid concentration and its signalling deregulation were also shown to maintain stomatal aperture and thus the growth of the scion when grafted onto tolerant rootstocks and ungrafted accessions under high salt concentration conditions. It was also demonstrated that a limitation of Na+ transport to leaves, as well as a more efficient transport and accumulation of K+ in roots and leaves, are essential to reach ion homeostasis and, thus, tolerance in pepper plants grafted onto tolerant rootstocks. Finally, the study of the molecular pathways of tolerance was a useful tool to confirm the physiological and agronomical behaviour of a pepper accession previously classified as tolerant, although new mechanisms were also found. The differentially expressed genes found were linked to hormonal signalling, plant growth and development, photoprotection, regulation of ion transporters and ROS detoxification. / Quiero agradecer al Instituto Valenciano de Investigaciones Agrarias (IVIA), al Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA) y al Ministerio de Ciencia, Innovación y Universidades por darme la oportunidad de disfrutar de la beca predoctoral FPI-INIA (proyectos RTA2013-00022-C02-1 y RTA2017-00030-C02-00) con la que he realizado esta tesis doctoral y he podido aprender tanto todos estos años, asistir a los congresos y realizar las estancias de investigación en el extranjero. / López Serrano, L. (2021). Unravelling the Physiological and Genetic Adaptation of Grafted Pepper under Saline and Hydric Stresses [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/162875 / Compendio

Tesis por compendio / [ES] La sequía y la salinidad son los factores ambientales que más afectan a las plantas, aunque en general, las plantas mediterráneas están bien adaptadas a las condiciones adversas. Las previsiones estiman que debido al calentamiento global las condiciones ambientales se volverán más estresantes, especialmente en las zonas semi-áridas y áridas como muchas áreas de la Península Ibérica. Estas condiciones pueden afectar a la presencia de muchas especies silvestres, en especial, de las que ya de por si están amenazadas, son raras o endémicas. Tanto la sequía como el estrés salino provocan la activación de una serie de mecanismos de defensa o respuesta de las plantas, que incluyen entre otros, el control del transporte iónico, la acumulación de solutos compatibles u osmolitos, y la activación de sistemas antioxidantes. Para contribuir a la conservación y/o reintroducción de las especies de interés en hábitats prioritarios se ha realizado un estudio multidisciplinar abarcando los parámetros que pueden afectar sus poblaciones, como el clima, el suelo, y la vegetación acompañante, junto a estudios comparativos sobre las respuestas a la sequía y a la salinidad. Para entender mejor los mecanismos de tolerancia se han incluido en el estudio además de los taxones de interés conservacionista, especies relacionadas genéticamente con diferentes niveles de tolerancia. El estudio presenta dos objetivos principales: i) establecer la tolerancia relativa al estrés hídrico y salino de las especies en base a su distribución en la naturaleza y en los análisis realizados en campo y, en función de la inhibición relativa de su crecimiento bajo condiciones provocadas de estrés; y, ii) evaluar los cambios bioquímicos inducidos por el estrés analizando diferentes mecanismos de respuesta (inhibición de la fotosíntesis, transporte iónico, acumulación de osmolitos, mecanismos antioxidantes). / [CA] La sequera i la salinitat són els factors ambientals que més afecten les plantes, encara que en general, les plantes mediterrànies estan ben adaptades a les condicions adverses. Les previsions estimen que a causa del calfament global les condicions ambientals es tornaran més estressants, especialment en les zones semi-àrides i àrides com moltes àrees de la Península Ibèrica. Aquestes condicions poden afectar la presència de moltes espècies silvestres, especialment, de les que ja de per si estan amenaçades, són rares o endèmiques. Tant la sequera com l'estrès salí provoquen l'activació d'una sèrie de mecanismes de defensa o resposta de les plantes, que inclouen entre altres, el control del transport iònic, l'acumulació de soluts compatibles u osmolits, i l'activació de sistemes antioxidants. Per a contribuir a la conservació i/o reintroducció de les espècies d'interès en hàbitats prioritaris s'ha realitzat un estudi multidisciplinari abastant els paràmetres que poden afectar les seues poblacions, com el clima, el sòl, i la vegetació acompanyant, al costat d'estudis comparatius sobre les respostes a la sequera i a la salinitat. Per a entendre millor els mecanismes de tolerància s'han inclòs en l'estudi a més dels tàxons d'interès conservacionista, espècies relacionades genèticament amb diferents nivells de tolerància. L'estudi presenta dos objectius principals: i) establir la tolerància relativa a l'estrès hídric i salí de les espècies sobre la base de la seua distribució en la naturalesa i en les anàlisis realitzades en camp i, en funció de la inhibició relativa del seu creixement sota condicions provocades d'estrès; i, ii) avaluar els canvis bioquímics induïts per l'estrès analitzant diferents mecanismes de resposta (inhibició de la fotosíntesi, transport iònic, acumulació de osmolits, mecanismes antioxidants). / [EN] Drought and salinity are the environmental factors that most affect plants, although in general Mediterranean plants are well adapted to adverse conditions. Predictions estimate that, due to global warming, environmental conditions will become more stressful, especially in semi-arid and arid areas, such as many areas of the Iberian Peninsula. These conditions may affect the presence of many wild species, especially those that are already threatened, rare or endemic. Both drought and salt stress cause the activation of a series of defence or response mechanisms in plants, which include, among others, the control of ionic transport, the accumulation of compatible solutes or osmolytes, and the activation of antioxidant systems. To contribute to the conservation and/or reintroduction of species of interest in priority habitats, a multidisciplinary study has been carried out covering parameters that may affect their populations, such as climate, soil and accompanying vegetation, together with comparative studies on responses to drought and salinity. To better understand tolerance mechanisms, genetically related species with different levels of tolerance have been included in the study, in addition to taxa of conservation interest. The study has two main objectives: i) to establish the relative tolerance to water and salt stress of the species according to their distribution in nature and based on field analyses and, according to the relative inhibition of their growth under stress-induced conditions; and, ii) to evaluate stress-induced biochemical changes by analysing different mechanisms (inhibition of photosynthesis, ionic transport, osmolyte accumulation, antioxidant mechanisms). / This research was partially funded by Project AICO/2017/039 from the Generalitat Valenciana. / González Orenga, S. (2021). Mecanismos de tolerancia a estrés salino e hídrico en plantas endémicas, raras o amenazadas [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/168443 / Compendio