47,537 research outputs found

    Revisão taxonómica do género Calendula L. (Asteraceae - Calenduleae) na Península Ibérica e Marrocos

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    The genus Calendula L. (Asteraceae - Calenduleae) includes, depending on the author, 10 to 25 species, distributed mainly in the Mediterranean basin. The taxonomy of this genus is considered to be extremely difficult, due to a great morphological variability, doubtfull relevance of some of the characters used to distinguish its species (e.g. the life form: annual or perennial; the habit: erect or diffuse, shape of the leaves, indumentum, relative size of the capitula and colour of disc or ray florets, achene morphology), but also due to the hybridization and polyploidization. Despite the numerous studies that have been published, no agreement on the classification and characters used to discriminate between taxa has been reached. A taxonomic study of the genus Calendula was conducted for the Iberian Peninsula and Morocco, aiming at (1) access the morphological variability between and within taxa, (2) confirm the chromosome numbers, (3) increase the nuclear DNA content estimations, (4) re-evaluate taxa delimitations and circumscription, and (5) reassess, and redefine, the descriptions and characters useful to distinguish taxa. In order to achieve a satisfying taxonomic core, extensive fieldwork, detailed morphometric analysis, chorological, karyological and genome size studies were conducted. For the Iberian Peninsula, four species were recognized, including nine subspecies (between these two new subspecies were described). For Morocco, including some taxa from Algeria and Tunisia 13 species were recognized (two new species and a nomenclatural change), including 15 subspecies (among these eight new subspecies were described). To corroborate the results obtained and to evaluate the evolutionary relationships among taxa, phylogenetic studies using molecular methods, such as ITS, microsatellites or other molecular markers, should be used.O g√©nero Calendula L. (Asteraceae - Calenduleae) inclui, dependendo do autor, 10 a 25 esp√©cies, distribu√≠das essencialmente na bacia do Mediterr√Ęneo. A taxonomia deste g√©nero √© considerada extremamente dif√≠cil, devido √† grande variabilidade morfol√≥gica, discutivel relev√Ęncia de alguns dos caracteres utilizados para distinguir suas esp√©cies (por exemplo, a forma de vida: anual ou perene, o h√°bito: erecto ou difuso, a forma das folhas, o indumento, o tamanho e a cor dos cap√≠tulos e a morfologia dos aqu√©nios), mas tamb√©m devido √† hibridiza√ß√£o e poliploidiza√ß√£o. Apesar dos in√ļmeros estudos que foram publicados, n√£o foi alcan√ßado um acordo sobre a classifica√ß√£o e os caracteres utilizados para discriminar as suas esp√©cies. Um estudo taxon√≥mico do g√©nero Calendula foi realizado para a Pen√≠nsula Ib√©rica e Marrocos, com o objectivo de (1) verificar a variabilidade morfol√≥gica, (2) confirmar o n√ļmero de cromossomas, (3) aumentar as estimativas de conte√ļdo em ADN, (4) reavaliar a delimita√ß√£o e a circunscri√ß√£o dos taxa, e (5) reavaliar e redefinir as descri√ß√Ķes e caracteres √ļteis para os distinguir. Para alcan√ßar uma robust√™s taxon√≥mica satisfat√≥ria, foram realizados extensos trabalhos de campo, an√°lise morfom√©trica detalhada, abordagens corol√≥gicas, cariol√≥gicas e quanto ao conte√ļdo em ADN. Para a Pen√≠nsula Ib√©rica, quatro esp√©cies foram reconhecidas, incluindo nove subesp√©cies (entre essas duas novas subesp√©cies foram descritas). Para Marrocos, incluindo alguns taxa da Argelia e Tunisia, foram reconhecidas 13 esp√©cies (duas novas e uma mudan√ßa nomenclatural), incluindo 15 subesp√©cies (entre essas oito novas subesp√©cies foram descritas). Para corroborar os resultados obtidos e avaliar as rela√ß√Ķes evolutivas e filogen√©ticas entre os taxa, estudos que utilizem diferentes m√©todos moleculares, tais como ITS, microsat√©lites ou outros marcadores moleculares, devem ser utilizados.Apoio financeiro do Laborat√≥rio Associado CESAM - Centro de Estudos do Ambiente e do Mar (AMB/50017) financiado por fundos nacionais atrav√©s da FCT/MCTES e cofinanciado pelo FEDER (POCI-01-0145-FEDER-007638), no √Ęmbito do Acordo de Parceria PT2020, e Compete 2020Programa Doutoral em Biologi

    Identification and analysis of the secretome of plant pathogenic fungi reveals lifestyle adaptation

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    The secretory proteome plays an important role in the pathogenesis of phytopathogenic fungi. However, the relationship between the large-scale secretome of phytopathogenic fungi and their lifestyle is not fully understood. In the present study, the secretomes of 150 plant pathogenic fungi were predicted and the characteristics associated with different lifestyles were investigated. In total, 94,974 secreted proteins (SPs) were predicted from these fungi. The number of the SPs ranged from 64 to 1,662. Among these fungi, hemibiotrophic fungi had the highest number (average of 970) and proportion (7.1%) of SPs. Functional annotation showed that hemibiotrophic and necrotroph fungi, differ from biotrophic and symbiotic fungi, contained much more carbohydrate enzymes, especially polysaccharide lyases and carbohydrate esterases. Furthermore, the core and lifestyle-specific SPs orthogroups were identified. Twenty-seven core orthogroups contained 16% of the total SPs and their motif function annotation was represented by serine carboxypeptidase, carboxylesterase and asparaginase. In contrast, 97 lifestyle-specific orthogroups contained only 1% of the total SPs, with diverse functions such as PAN_AP in hemibiotroph-specific and flavin monooxygenases in necrotroph-specific. Moreover, obligate biotrophic fungi had the largest number of effectors (average of 150), followed by hemibiotrophic fungi (average of 120). Among these effectors, 4,155 had known functional annotation and pectin lyase had the highest proportion in the functionally annotated effectors. In addition, 32 sets of RNA-Seq data on pathogen-host interactions were collected and the expression levels of SPs were higher than that of non-SPs, and the expression level of effector genes was higher in biotrophic and hemibiotrophic fungi than in necrotrophic fungi, while secretase genes were highly expressed in necrotrophic fungi. Finally, the secretory activity of five predicted SPs from Setosphearia turcica was experimentally verified. In conclusion, our results provide a foundation for the study of pathogen-host interaction and help us to understand the fungal lifestyle adaptation

    Mechanisms of As, Cd, Pb, and Zn hyperaccumulation by plants and their effects on soil microbiome in the rhizosphere

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    Excess potentially toxic elements (PTEs), including arsenic (As), cadmium (Cd), lead (Pb), and zinc (Zn), above permissible limits in the environment, have detrimental effects on trophic levels. Hence, imperative to devise advertent measures to address this situation, especially in the soil ecosystem: the major reservoir of many PTEs. Using aerial plant parts (shoot) to accumulate As, Cd, Pb, and Zn - hyperaccumulators are considered a permanent approach to PTE removal from soils. This communication expatiated the principles that govern the hyperaccumulation of plants growing on As, Cd, Pb, and Zn-contaminated soils. The contribution of soil microbial communities during hyperaccumulation is well-elaborated to support the preference for this remediation approach. The study confirms a flow direction involving PTE uptake‚Äďtranslocation‚Äďtolerance‚Äďdetoxification by hyperaccumulators. Rhizosphere microbes exhibit a direct preference for specific hyperaccumulators, which is associated with root exudations, while the resultant formation of chelates and solubility of PTEs, with soil physicochemical properties, including pH and redox potential, promote uptake. Different compartments of plants possess specialized transporter proteins and gene expressions capable of influx and efflux of PTEs by hyperaccumulators. After PTE uptake, many hyperaccumulators undergo cellular secretion of chelates supported by enzymatic catalysis and high transport systems with the ability to form complexes as tolerance and detoxification mechanisms. The benefits of combining hyperaccumulators with beneficial microbes such as endophytes and other rhizosphere microbes for PTE removal from soils are vital in enhancing plant survival and growth, minimizing metal toxicity, and supplying nutrients. Inoculation of suitable rhizosphere microbes can promote efficient cleaning of PTEs contaminated sites utilizing hyperaccumulator plants

    Implementation of Bayesian inference MCMC algorithm in phylogenetic analysis of Dipterocarpaceae family

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    Dipterocarpaceae is one of the most prominent plant families, with more than 500 members of species. This family mostly used timber plants for housing, making ships, decking, and primary materials for making furniture. In Indonesia, many Dipterocarpaceae species have morphological similarities and are challenging to recognize in the field. As a result, the classification process becomes difficult and even results are inconsistent when viewed only from the morphology. This research will analyze the phylogenetic tree of Dipterocarpaceae based on the chloroplast matK gene. The aim of the research is to classify the phylogenetics tree of Dipterocarpaceae family using Bayesian inference algorithm. This research used the chloroplast gene instead of morphological characters which has more accurate. The analysis steps are collecting data, modifying the structure sequence name, sequence alignment, constructing tree by using Markov Chain Monte Carlo (MCMC) from Bayesian Inference, and evaluating and analyzing the phylogenetic tree. The results showed that the tree constructed based on the gene is different from the tree based on morphology. Based on the morphological, Dipterocarpus should be in the Dipterocarpeae tribe but based on the similarity of its genes, Dipterocarpus is more similar to the Shoreae tribe.  

    A chromosome-scale genome assembly of Castanopsis hystrix provides new insights into the evolution and adaptation of Fagaceae species

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    Fagaceae species dominate forests and shrublands throughout the Northern Hemisphere, and have been used as models to investigate the processes and mechanisms of adaptation and speciation. Compared with the well-studied genus Quercus, genomic data is limited for the tropical-subtropical genus Castanopsis. Castanopsis hystrix is an ecologically and economically valuable species with a wide distribution in the evergreen broad-leaved forests of tropical-subtropical Asia. Here, we present a high-quality chromosome-scale reference genome of C. hystrix, obtained using a combination of Illumina and PacBio HiFi reads with Hi-C technology. The assembled genome size is 882.6 Mb with a contig N50 of 40.9 Mb and a BUSCO estimate of 99.5%, which are higher than those of recently published Fagaceae species. Genome annotation identified 37,750 protein-coding genes, of which 97.91% were functionally annotated. Repeat sequences constituted 50.95% of the genome and LTRs were the most abundant repetitive elements. Comparative genomic analysis revealed high genome synteny between C. hystrix and other Fagaceae species, despite the long divergence time between them. Considerable gene family expansion and contraction were detected in Castanopsis species. These expanded genes were involved in multiple important biological processes and molecular functions, which may have contributed to the adaptation of the genus to a tropical-subtropical climate. In summary, the genome assembly of C. hystrix provides important genomic resources for Fagaceae genomic research communities, and improves understanding of the adaptation and evolution of forest trees

    The phenolic constituents and antimicrobial activity of Xanthium spinosum (Asteraceae) extracts

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    Xanthium spinosum is a cosmopolitan annual herb used in traditional medicine worldwide. Although known from ethnobotanical studies, the species is scarcely investigated from the aspects of phytochemistry and biological activity. Therefore, the phenolic composition and biological activity of X. spinosum were examined. Plant specialised metabolites (phenolics) extracted from the roots, leaves and fruits with dichloromethane:methanol (1:1) were analysed by liquid chromatography mass spectrometry (LC-MS). In total 10 phenolic compounds were identified and quantified. Six compounds were common to all the extracts. Chlorogenic acid was the most abundant constituent in all the extracts (4.262 mg/g in the fruit extract, 0.820 mg/g in the leaf extract, and 0.540 mg/g in the root extract). The biological activity (antimicrobial and antibiofilm) of the extracts was tested against 12 microfungi and 12 bacterial strains by the microdilution method. All the extracts exhibited moderate antimicrobial and antibiofilm activity and inhibited the growth of most of the examined microorganisms. The obtained results indicate the potential role of the tested extracts in pharmacy and medicine

    Caracterización funcional de la subunidad EAF6 del complejo NuA4 en la regulación del tiempo de floración en Arabidopsis thaliana

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    Las plantas, como organismos s√©siles, han desarrollado mecanismos complejos de adaptaci√≥n que les permiten responder a las condiciones cambiantes del medio que les rodea, modulando su desarrollo para maximizar el √©xito reproductivo y la supervivencia. A lo largo de su desarrollo las plantas atraviesan diferentes fases, y el momento en que tiene lugar el paso de la etapa de crecimiento vegetativo al reproductivo, o transici√≥n floral, es crucial en el ciclo vital de estas, ya que de √©l depende su capacidad de transferir los genes a la siguiente generaci√≥n. Por ello, el tiempo de floraci√≥n se encuentra muy finamente regulado. La remodelaci√≥n de la cromatina desempe√Īa un papel clave en el establecimiento y mantenimiento de los patrones espacio‚Äďtemporales de expresi√≥n g√©nica que regulan las transiciones de fase del desarrollo vegetal, y particularmente en el control de la expresi√≥n de genes maestros de la transici√≥n floral. Las modificaciones post-traduccionales de las histonas, incluida la acetilaci√≥n, se encuentran entre los mecanismos de remodelaci√≥n de la cromatina m√°s relevantes que operan en las c√©lulas eucariotas. La acetilaci√≥n de residuos de lisina en las histonas est√° muy conservada evolutivamente y est√° implicada en multitud de procesos celulares y de desarrollo. Por ello, los niveles de acetilaci√≥n de las histonas son finamente modulados por la acci√≥n antag√≥nica de las acetiltransferasas (HATs) y las deacetilasas de histonas. En plantas se han descrito diferentes familias de HATs entre las que se encuentra la familia MYST, que comprende hom√≥logos de la subunidad catal√≠tica del complejo NuA4 (NuA4-C) de levaduras. Este complejo remodelador de la cromatina media la acetilaci√≥n de los extremos amino terminales de las histonas H4, H2A y H2A.Z, y est√° implicado en procesos de transcripci√≥n y reparaci√≥n del DNA, silenciamiento g√©nico, progresi√≥n del ciclo celular y estabilidad de los cromosomas. La existencia y composici√≥n de un posible NuA4-C en plantas sigue siendo a√ļn una cuesti√≥n sin resolver. En plantas se han identificado hom√≥logos para casi todas las subunidades de NuA4-C de levaduras, incluida la subunidad catal√≠tica, lo que sugiere que este complejo tambi√©n podr√≠a estar presente en organismos vegetales. Sin embargo, el conocimiento sobre la funci√≥n del posible NuA4-C de plantas es muy limitado. En los √ļltimos a√Īos el estudio de mutantes de Arabidopsis deficientes en subunidades de este complejo ha comenzado a revelar funciones para estos hom√≥logos en varios procesos biol√≥gicos como el inicio de la floraci√≥n, el desarrollo de los gametofitos, la proliferaci√≥n celular, el estr√©s, el crecimiento y las respuestas hormonales entre otros. A lo largo de esta Tesis Doctoral se ha profundizado en la caracterizaci√≥n funcional del posible NuA4-C de Arabidopsis y su implicaci√≥n en el control de la transici√≥n floral y otros procesos de desarrollo de plantas. Para ello nos hemos centrado en la caracterizaci√≥n gen√©tica, molecular y funcional de la subunidad EAF6 de Arabidopsis. No se conoce la funci√≥n que desempe√Īa a nivel bioqu√≠mico esta prote√≠na en ning√ļn organismo eucari√≥tico, mientras que en plantas no se hab√≠a abordado su caracterizaci√≥n hasta el momento. Las aproximaciones experimentales que hemos llevado a cabo en este trabajo nos han permitido desvelar que la prote√≠na EAF6 de Arabidopsis interviene en el control de diferentes procesos de desarrollo, entre los que destaca un papel crucial en la inducci√≥n de la floraci√≥n en condiciones de fotoperiodo no inductivas y en una correcta respuesta de floraci√≥n a cambios en la temperatura ambiental. Los an√°lisis transcript√≥micos realizados han revelado que EAF6 juega un papel central en el control de la expresi√≥n g√©nica a nivel global, y est√° implicado en la regulaci√≥n de genes que participan en la modulaci√≥n del tiempo de floraci√≥n tales como FLC, MAF4, MAF5 y AGL19, que podr√≠an mediar el efecto de esta posible subunidad de NuA4-C sobre el inicio de la transici√≥n floral en Arabidopsis. Adem√°s, los an√°lisis de inmunoprecipitaci√≥n de cromatina que hemos llevado a cabo confirman que esta regulaci√≥n podr√≠a tener lugar a trav√©s de procesos de regulaci√≥n epigen√©tica, ya que los mutantes eaf6 muestran alteraciones en los niveles de la marca represora H3K27me3 en determinados genes de floraci√≥n. Por otro lado, nuestros resultados muestran que EAF6 est√° tambi√©n implicado en otros procesos de desarrollo vegetal tales como el crecimiento de la planta y las hojas, la biog√©nesis de cloroplastos, y podr√≠a participar en el desarrollo del polen. Adem√°s, los resultados obtenidos en aproximaciones gen√©ticas y bioqu√≠micas llevadas a cabo en este trabajo indican que el complejo Piccolo-NuA4 de levaduras puede estar conservado en plantas. Este subm√≥dulo de NuA4-C est√° constituido por las subunidades Esa1, Epl1, Yng2 y Eaf6, y es responsable de la acetilaci√≥n inespec√≠fica de la cromatina y de la interacci√≥n de NuA4-C con los nucleosomas. En este trabajo hemos demostrado que EAF6 interacciona f√≠sicamente con las prote√≠nas EPL1A/B e ING2, y el gen que codifica esta prote√≠na interacciona gen√©ticamente con los loci HAM1, EPL1B e ING1/2 en el control de diferentes aspectos del desarrollo, incluida la transici√≥n floral. En conjunto, todos estos resultados apoyan el papel de un posible NuA4-C de plantas en la regulaci√≥n de la transici√≥n floral en Arabidopsis. ----------ABSTRACT---------- Plants, as sessile organisms, have developed complex adaptation mechanisms that allow them to respond to environmental changing conditions, modulating their development to maximize their fitness and survival. Along their development plants go through different growth phases, and the timing of the transition from the vegetative to the reproductive stage, known as floral transition, is critical in the life cycle of plants since their reproductive success depends on it. Therefore, flowering time is a very fine-tuned process. Chromatin remodeling is key for the establishment and maintenance of the spatial and temporal gene expression patterns that modulate the phase transitions along plant development, and particularly the expression of master genes involved in regulation of the floral transition. Post-translational histone modifications, including acetylation, are one of the most relevant chromatin remodeling mechanisms operating in eukaryotic cells. The acetylation of lysine residues in histones is evolutionarily conserved and is involved in a plethora of cellular and developmental processes. Therefore, the acetylation levels of lysine residues in the amino terminal tails of histones are tightly modulated by the antagonistic action of histone acetyltransferases (HATs) and deacetylases. In plants, different families of HATs have been described, including the MYST family that comprises homologs of the catalytic subunit of the yeast NuA4 complex (NuA4-C). This chromatin remodeling complex mediates the acetylation of histones H4, H2A, and H2A.Z, and is involved in DNA transcription and repair, gene silencing, cell cycle progression, and chromosome stability. The existence and composition of a NuA4-like-C in plants remains an open question nowadays. In plants, homologs for almost all yeast NuA4-C subunits have been identified, including the catalytic subunit, suggesting that this complex could also be present in plant species. However, the knowledge about the role of the possible plant NuA4-C is very limited. Over the last few years the study of Arabidopsis mutants deficient in subunits of this complex has started to reveal functions for these homologs in various biological processes such as the floral transition, gametophyte development, cell proliferation, stress responses, growth, and hormonal responses among others. In this Doctoral Thesis we have addressed the functional characterization of the possible Arabidopsis NuA4-C and its involvement in the control of the floral transition and additional plant development processes. With this aim, we have focused on the genetic, molecular, and functional characterization of the Arabidopsis EAF6 subunit. The biochemical function of this protein remains unknown in any eukaryotic organism while in plants no EAF6 protein had been studied. Experimental approaches tackled in this work have allowed us to reveal that AtEAF6 participates in the control of different developmental processes in Arabidopsis, including a crucial role in flowering promotion under non-inductive photoperiods as well as in the flowering response to changes in ambient temperature. The transcriptomic analyses performed have revealed that EAF6 is involved in genome wide transcriptional control and is required for the regulation of flowering-related genes such as FLC, MAF4, MAF5 and AGL19 that could mediate the effect of this putative NuA4-C subunit on the timing of the floral transition in Arabidopsis. Moreover, chromatin immunoprecipitation assays carried out have confirmed that this regulation could take place through changes in the organization of chromatin since eaf6 mutants display alterations in the levels of the repressive mark H3K27me3 in specific flowering loci. Additionally, our results show that EAF6 could be also involved in other developmental processes such as plant and leaf growth, chloroplast biogenesis, and could participate in pollen development. In addition, results obtained in genetic and biochemical approaches carried out in this work indicate that the yeast Piccolo-NuA4 complex can be conserved in plants. The Piccolo-NuA4 complex is a sub-module of NuA4-C formed by the Esa1, Epl1, Yng2, and Eaf6 subunits, and is responsible for the non-specific chromatin acetylation and the interaction of NuA4-C with nucleosomes. In this work, we have shown that EAF6 physically interacts with the EPL1A/B and ING2 proteins, while the gene encoding this putative NuA4-C subunit genetically interacts with HAM1, EPL1B, and ING1/2 loci in the regulation of different developmental processes, including the floral transition. Taken together, all these results support a role for a possible EAF6-containing NuA4-C in the regulation of the floral transition in Arabidopsis

    H. portulacoides and J. maritimus em sapal contaminado por merc√ļrio: acumula√ß√£o de metal, padr√Ķes bioqu√≠micos e lipid√≥micos

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    Mestrado em Biologia Molecular e CelularThe salt marshes, one of the most productive ecosystems, serves as the sink for contaminants, namely metals from industries, reducing in this way the contamination of surrounding ecosystems. Although, as levels of contaminants, the ability of salt marshes to incorporate wastes can be impaired. In the aquatic environment, high mercury (Hg) pollution is mainly due to metal discharge of effluents from chloralki plants containing high concentrations of this metal. Mercury has been recognized as heavy metal and extremely toxic to plants interfering with several crucial cellular processes. This study evidenced the importance to understand the analysis that plants under environmental exposed to Hg and to evaluate impact of Hg toxicity in plants salt marsh communities. Better knowledge on these accumulation aspects will evaluate the stress imposed by Hg on primary production in salt marsh plants and adaptation of mobility of the metal in the ecosystem. As well as the molecular mechanisms mercury tolerance, which are important to clean efficiently Hg contaminated systems in order to an effective restoration is achieved. In this way, the work focused on two species of halophytes, Halimione portulacoides and Juncus maritimus collected at two sites of the Ria de Aveiro contaminated by mercury, considered s1 as less contaminated site and s2 as the most contaminated site. Thus, this work was designed to (1) evaluate how Hg distribution in plants would avoid high Hg concentrations (2) which way plants would retain Hg toxicity by triggering antioxidant responses. Indeed, most of biochemical parameters determinate the evidence of different responses by different concentration of Hg in the sediment (s1 and s2) and (3) plants can or not modify their lipid composition by Hg toxicity through the UPLC-MS methodology. This study demonstrated that both plant species restricted Hg uptake. However, the process was more efficient in H. portulacoides. Was observed differences in the amount of Hg accumulated by both species. Allocation patterns also differs between species. H. portulacoides showed different levels of Hg between leaves, stems and roots, while J. maritimus accumulated the higher levels of Hg in roots. The conjugation of both process, absorption and translocation resulted in similar Hg concentrations in stems and leaves and much higher Hg levels in J. maritimus roots. The results obtained demonstrate that Hg generated oxidative damage in the roots of both species and in leaves of H. portulacoides. Differences in LPO between species obtaining for each specie reflects not only the level of Hg accumulated and Hg distribution but also the ability to trigger the defense mechanisms. J. maritimus was able to increase the protein levels and DHAR activity in roots and rhizomes and GSTs in rhizomes. H. portulacoides was not able to induce the antioxidant enzymatic responses. Although in leaves antioxidant molecules such carotenoids and őĪ-tocopherol were enhanced. In lipidome study, species also showed differences. In H. portulacoides, phospholipids decreased in all the organs analyzed, which can subject an alteration of membrane permeability. In addition, galactolipids decreased, reducing the efficiency on photosynthesis. However, őĪ-tocopherol increased, and so better protection to chloroplast membranes and maintenance of photosynthetic activity provided. In J. maritimus, lipid changes were only detected in roots and rhizomes, increasing lipid permeability and explaining the higher bioaccumulation at high Hg concentrations. Phyto sterols decreased significantly in roots and lead to alterations of permeability membrane. őĪ-tocopherol was detected in both organs of J. maritimus, a decrease that demonstrate an ineffective Hg contamination. This study may be a starting point for further work, namely in other marshes, in other species and with other metals. Understanding the mechanisms inherent to in heavy metal tolerance in marsh plants and the changes in lipid composition are important to detect the impact of metals in these ecosystems.Os sapais, considerados um dos ecossistemas mais produtivos, servem como reservat√≥rio para contaminantes, nomeadamente metais provenientes de industrias, reduzindo desta forma a contamina√ß√£o dos ecossistemas circundantes. Em ambiente aqu√°tico, a polui√ß√£o por merc√ļrio (Hg) √© principalmente devido a descargas de efluentes de industrias contendo concentra√ß√Ķes elevadas deste metal. O merc√ļrio √© reconhecido como sendo um metal pesado e extremamente t√≥xico para as plantas, interferindo desta forma em v√°rios processos celulares cruciais. Este estudo evidenciou a import√Ęncia de compreender o processo aquando da exposi√ß√£o das plantas ao merc√ļrio e desta forma avaliar o impacto da toxicidade do Hg nas comunidades de sapais. Uma melhor compreens√£o sobre estes aspetos de acumula√ß√£o avaliar√° o stress imposto pelo Hg sobre a produ√ß√£o prim√°ria em plantas de sapal e a adapta√ß√£o das plantas no ecossistema. Adicionalmente este estudo permite tamb√©m a interpreta√ß√£o dos mecanismos moleculares da toler√Ęncia ao merc√ļrio das plantas uma vez que estas s√£o importantes para uma limpeza eficiente dos sistemas contaminados por Hg para uma restaura√ß√£o efetiva. Desta forma, o trabalho incidiu em duas esp√©cies de plantas hal√≥fitas, Halimione portulacoides e Juncus maritimus recolhidas em dois locais da Ria de Aveiro contaminados por merc√ļrio, s1 considerado como o local menos contaminado e s2 como o local mais contaminado. Este estudo foi projetado para (1) avaliar como a distribui√ß√£o de Hg em plantas (2) de que forma as plantas iram reter a toxicidade do Hg desencadeando respostas antioxidantes. De fato, a maioria dos par√Ęmetros bioqu√≠micos determinaram a evid√™ncia de respostas diferentes por concentra√ß√Ķes diferentes de Hg no sedimento (s1 e s2) e (3) as plantas poderiam ou n√£o modificar sua composi√ß√£o lip√≠dica por toxicidade de Hg atrav√©s da metodologia UPLC-MS. Este estudo demonstrou que ambas as esp√©cies de plantas restringiam a absor√ß√£o de Hg. No entanto, o processo foi mais eficiente em H. portulacoides. Foram observadas diferen√ßas na quantidade de Hg acumulada por ambas as esp√©cies. Os padr√Ķes de aloca√ß√£o tamb√©m diferem entre as esp√©cies. H. portulacoides apresentou diferentes n√≠veis de Hg entre folhas, caules e ra√≠zes, enquanto J. maritimus acumulou os n√≠veis mais elevados de Hg nas ra√≠zes. A conjuga√ß√£o dos processos, absor√ß√£o e transloca√ß√£o resultou em concentra√ß√Ķes semelhantes de Hg em caules e folhas e n√≠veis de Hg muito elevados em ra√≠zes de J. maritimus. Os resultados obtidos demonstram que o Hg gerou danos oxidativos nas ra√≠zes de ambas as esp√©cies e nas folhas de H. portulacoides. As diferen√ßas na LPO entre esp√©cies que se obteve refletem n√£o apenas o n√≠vel de Hg acumulado e distribui√ß√£o de Hg, mas tamb√©m a capacidade de desencadear mecanismos de defesa. J. maritimus foi capaz de aumentar os n√≠veis proteicos e atividade DHAR em ra√≠zes e rizomas e GSTs em rizomas. H. portulacoides n√£o conseguiu induzir respostas enzim√°ticas antioxidantes. Contudo, nas folhas as mol√©culas antioxidantes como carotenoides e őĪ-tocoferol foram aumentadas. No estudo do lipidoma, as esp√©cies tamb√©m apresentaram diferen√ßas. Em H. portulacoides, os fosfol√≠pidos diminu√≠ram em todos os √≥rg√£os analisados, o que pode sugerir a altera√ß√£o da permeabilidade da membrana. Al√©m disso, os galactol√≠pidos diminu√≠ram a efici√™ncia na fotoss√≠ntese. No entanto, o őĪ-tocoferol aumentou, proporcionando assim uma melhor prote√ß√£o √†s membranas de cloroplastos e manuten√ß√£o da atividade fotossint√©tica. Em J. maritimus, as altera√ß√Ķes lip√≠dicas s√≥ foram detetadas em ra√≠zes e rizomas, aumentando a permeabilidade lip√≠dica e explicando a maior bioacumula√ß√£o de concentra√ß√Ķes elevadas de Hg. Os fito-ester√≥is diminu√≠ram significativamente nas ra√≠zes e levaram a altera√ß√Ķes da membrana de permeabilidade. O őĪ-tocoferol diminuiu em ambos os √≥rg√£os de J. maritimus, demonstrando a inefici√™ncia para a contamina√ß√£o por Hg. Este estudo pode ser um ponto de partida para novos trabalhos, nomeadamente em outros sapais, em outras esp√©cies e com outros metais. Compreender os mecanismos inerentes √† toler√Ęncia de metais pesados em plantas de sapais e as mudan√ßas na composi√ß√£o lip√≠dica s√£o importantes para detetar o impacto dos metais nestes ecossistemas

    Rice responses to silicon addition at different Fe status and growth pH. Evaluation of ploidy changes

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    It has been described in rice that Si only plays a physical barrier that does not allow Fe to enter cell apoplast, causing Fe deficiency responses even under Fe sufficiency growth conditions. Most of the conclusions were attained at acidic pH, but rice is also grown at calcareous conditions, which especially induce Fe deficiency in the plants. In this study, we assay the effect of Si in rice suffering both Fe deficiency and sufficiency in hydroponics at two pHs (5.5 and 7.5). Plant biometric parameters, ROS concentration, enzymatic activities, and total phenolic compounds, as well as ploidy levels, have been determined. In general, both pHs promoted similar rice responses under Fe sufficiency and deficiency status, but at pH 7.5, stress was favored. Flow cytometry studies revealed that Fe deficiency increased the percentage of cells in higher ploidy levels. Moreover, under this Fe status, Si addition enhanced this effect. This increase contributed to maintaining chloroplast structure which may have preserved antioxidant activities, and fortified cell walls, diminishing Fe uptake. The first is considered a beneficial effect as plants presented acceptable SPAD values, well chloroplast structure, and qualitatively high fluorescence observed by confocal microscopy, even under Fe deficiency. But contributes to intensify the Fe shortage, by decreasing apoplast Fe pools. In summary, Si addition to rice plants may not only behave as an apoplastic barrier but may also protect plant chloroplast and alter the plant endoreplication cycle, giving a memory effect to cope with present and future stressesThis research was funded by FEDER/Spanish Ministry of Science, Innovation, and Universities Project: RTI2018-096268-B-I00 and BES2014-070900 and partially supported by Comunidad de Madrid (Spain) and Structural Funds 2014‚Äď2020 (ERDF and ESF) (project AGRISOST-CM S2018/BAA-4330

    Exploration of Ulva-holobiont diversity in Portugal: any lesson to learn for cultivation and use?

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    Nesta era do Antropoceno, entre desafios relacionados com a sobrepopula√ß√£o e altera√ß√Ķes clim√°ticas, a necessidade de substituir os m√©todos tradicionais de explora√ß√£o de recursos do nosso planeta por alternativas sustent√°veis √© cada vez mais urgente. Uma alternativa promissora para contrapor os efeitos adversos de pr√°ticas convencionais de agricultura √© a aquacultura de macroalgas. Al√©m do seu papel crucial como produtoras prim√°rias, criadoras de habitat e biorremediadoras, as macroalgas podem ajudar com a sequestra√ß√£o de carbono. Estas representam tamb√©m uma fonte sustent√°vel e valiosa do ponto de vista comercial enquanto alimento para humanos ou para animais, e podem ser aplicadas a outras √°reas como higiene pessoal, medica√ß√£o, e produ√ß√£o de biocombust√≠veis. At√© ao momento t√™m sido sobretudo pa√≠ses asi√°ticos a utilizar uma grande variedade de macroalgas, enquanto que na Europa a potencial diversidade que pode ser utilizada para cultivo ainda n√£o foi devidamente explorada. O g√©nero de algas verdes Ulva √© particularmente interessante para a ind√ļstria alimentar devido ao seu elevado valor nutricional. Adicionalmente, tem sido alvo de uma crescente aten√ß√£o cient√≠fica devido √† sua recente aplica√ß√£o enquanto modelo para o estudo de intera√ß√Ķes entre macroalgas e bact√©rias. Comunidades bacterianas associadas a macroalgas (microbiomas) t√™m sido reconhecidas por influenciar processos metab√≥licos essenciais entre o sistema alga-bact√©ria (holobionte). Certos tipos de bact√©rias providenciam ao hospedeiro vitaminas e fito-hormonas para crescimento e morfog√©nese, enquanto outros aparentam facilitar a adapta√ß√£o a stressores ambientais. Contudo, a quest√£o de como √© determinada a composi√ß√£o do microbioma continua a ser um debate controverso e existem diferentes teorias para explicar este fen√≥meno. A teoria da lotaria baseia a composi√ß√£o do microbioma em processos estoc√°sticos, a especificidade ao hospedeiro prop√Ķe que a esp√©cie hospedeira determina que bact√©rias s√£o ‚Äúrecrutadas‚ÄĚ, enquanto a especificidade funcional ao hospedeiro indica que as bact√©rias se juntam de acordo com as suas fun√ß√Ķes e n√£o √† sua taxonomia. Finalmente, fatores ambientais tamb√©m mostraram ser importantes na composi√ß√£o do microbioma. Embora todos os fatores indicados mostrarem ter import√Ęncia, pouco se sabe sobre o fator principal que determina a composi√ß√£o de microbioma no g√©nero Ulva. Assim, neste estudo, diferentes esp√©cies de Ulva foram recolhidas ao longo da costa sul e sudoeste de Portugal em diferentes ambientes e identificadas atrav√©s do gene de alongamento do cloroplasto (tufA), e os seus microbiomas associados foram analisados atrav√©s da determina√ß√£o do perfil do gene de ARNr 16S. Numa etapa mais avan√ßada, os dados filogen√©ticos foram combinados com os dados metagen√≥micos para avaliar o n√≠vel de especificidade ao hospedeiro e/ou regi√£o. Foi dada aten√ß√£o especial a abund√Ęncias de grupos particulares de bact√©rias: taxa produtores de vitamina B12 (ben√©ficos) e ‚Äúambivalentes‚ÄĚ (potencialmente prejudiciais). Em conclus√£o, estes aspectos foram analisados de forma a perceber que li√ß√Ķes podem ser tiradas para o cultivo futuro e uso de diferentes holobiontes Ulva. Seis esp√©cies diferentes do g√©nero Ulva foram identificadas com sucesso com o uso do gene marcador tufA: U. rigida, U. compressa, U. californica/flexuosa, U. australis, Ulva sp.1, Ulva sp.2. A esp√©cie n√£o-ind√≠gena U. australis foi registada pela primeira vez em Portugal, assim como duas novas entidades. A suposi√ß√£o que U. californica e U. flexuosa formam um complexo (i.e. U. californica/flexuosa) foi verificada, e a distin√ß√£o gen√©tica da U. rigida relativamente √†s suas parentes U. laetevirens e U. lacutca foi desenvolvida. Os microbiomas examinados neste estudo diferenciaram-se na sua composi√ß√£o e diversidade entre esp√©cies Ulva e foram dominados maioritariamente pelas ordens Flavobact√©rias, Rhodobact√©rias, Caulobact√©rias, e Pirellulales. A √ļltima destas, j√° identificada como detentora de um conjunto de genes relacionados com resposta a stresses ambientais (i.e. Rhodopirellula), foi especialmente caracter√≠stica da U. compressa. Foi identificada especificidade ao hospedeiro clara e not√°vel para U. rigida e U. compressa, respectivamente, com sinais de especificidade secund√°ria √† regi√£o a um n√≠vel intrahospedeiro, predominantemente para U. compressa. A possibilidade de determinar a composi√ß√£o do microbioma com base unicamente em processos estoc√°sticos (lotaria) ou apenas em fatores ambientais p√īde ser descartada. A √ļnica excep√ß√£o foi o microbioma de U. californica/flexuosa de uma bacia artificial onde as condi√ß√Ķes ambientais distintivas aparentam ter tido um elevado impacto na composi√ß√£o e levaram a uma elevada abund√Ęncia de bact√©rias ben√©ficas (Flavobacteriales). Seguindo o racioc√≠nio acima utilizado, as esp√©cies U. compressa, U. rigida e U. californica/flexuosa foram propostas para ser de interesse especial para uso comercial. Com base numa elevada quantidade de Rhodopirellula e uma boa representa√ß√£o de Dinoroseobacter, U. compressa √© assim recomendada para ser cultivada para consumo humano, conforme sugerido por estudos pr√©vios. Devido √† sua especificidade ao hospedeiro, a U. rigida poder√° ser uma candidata apropriada para usos industriais para fornecer uma quantidade est√°vel de compostos provenientes de bact√©rias espec√≠ficas. A U. californica/ flexuosa poder√° ser uma candidata adequada para a produ√ß√£o de vitamina B12 devido √† possibilidade da sua capacidade de elevar a quantidade de Flavobact√©rias sob certas condi√ß√Ķes ambientais. No seu todo, estas descobertas t√™m importantes implica√ß√Ķes pois a especificidade ao hospedeiro permite o uso de microbiomas como uma ferramenta de delimita√ß√£o de esp√©cies, traceamento de esp√©cies n√£o-ind√≠genas (e. g. U. australis) e usos industriais para obter compostos espec√≠ficos derivados de bact√©rias em Ulva cultivada.In the context of the ever-growing interest in seaweed aquaculture as sustainable alternative to traditional farming practices, here, the potential of the green seaweed genus Ulva for cultivation and use was assessed. Ulva is particularly interesting for science and industry owing to its high nutritional value, variety of applications, and use as model organism to study seaweed-bacterial interactions. Seaweed associated bacterial communities (microbiomes) have been recognized to influence essential metabolic processes within the alga-bacteria system (holobiont). How the microbiome composition is determined remains a controversial debate and different theories exist to explain the process (i.e. lottery, host-specificity, "functional host-specificity", and environmental factors). Hence, this study aimed to assess the importance of the host and/or region for the determination of the microbiome by means of combining phylogenetic data based on DNA barcoding of the chloroplast elongation factor (tufA) gene of various species of Ulva from Portugal with metagenomic data of their respective microbiomes, analysed via 16S rRNA gene profiling. Special attention was paid to particular bacterial groups, vitamin B12 producers (beneficial) and "the ambivalent" (potentially harmful). The different aspects were viewed under the collective question of what lessons could be learned for future cultivation and use of these holobionts. Six different Ulva species (U. rigida, U. compressa, U. californica/flexuosa, U. australis, Ulva sp.1, Ulva sp.2) were identified, among them the non-indigenous species (NIS) U. australis, recorded for the first time in Portugal, and two potentially new entities. Host-specificity emerged as primary factor in at least two species with signs of secondary region-specificity on a within-host level, whereas a determination purely based on lottery or environmental factors could be ruled out. Additionally, microbiomes were unobtrusive in the abundance of the ambivalent bacteria and diverse in common vitamin B12 producers, suggesting Ulva once more suitable for consumption. Altogether, these findings have important implications for using the microbiome as additional species-delimitation tool, tracing of NIS and industrial strategies to increase specific bacterial-derived target compounds in farmed Ulva
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