143 resultados para estômatos
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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(Silicon location through backscattered electron imaging and X-ray microanalysis in leaves of Cyperus ligularis L. and Rhynchospora aberrans C. B. Clarke (Cyperaceae)). The Cyperaceae show the ability to incorporate silicon by depositing colloidal silica, which is recorded by the occurrence of projections in the form of cones, in inner tangential walls of some epidermal cells or "silica cells". Leaves of C. ligularis and R. aberrans were analyzed through the technique of electron backscatter. Cyperus ligularis accumulates silica, in addition to "silica cells", in some stomata, trichomes and the cell walls that surround the cavities of the aerenchyma. The silica in the latter occurs in various forms; however, the cells located near the vascular bundles have conical projections, similar to those of the epidermis. Rhynchospora aberrans presents "silica cells" whose projections have tapered "satellites". In this species, silica also occurs in stomata and certain epidermal cells adjacent to them. It appears that the silicon deposition occurs in combination with the wall (with no apparent structural changes), and structures of secretion, or projections of the wall. These structural changes in the species, and location, are probably related to functional and environmental factors, especially the soil, in addition to relation with taxonomic groups.
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The taxonomic delimitation at the species level in plants is not an easy task due to the large polymorphism of plants. In this project we aimed to evaluate three morphotypes (forms) of Cryptanthus zonatus (Vis.) Beer ( Bromeliaceae, Bromelioideae ) described in the literature using fl oral biology and phenology, as well as flo ral morphology and leaf anatomy . These studies were conducted in the Parque Estadual das Dunas de Natal, Rio Grande Norte (RN) and Private Reserve of Natural Patrimony Mata Estrela , in the municipality of Ba í a Form osa. The survey of the phenology of the morphotypes involved monthly specimen observation in the field, during one year. In each visit, we observed the status of flowering and fruiting phenophases of the population of the three forms of C. zonatus . For flo ral biology we sought to evaluate data like: observed floral visitors, nectar volume and concentration, time of anthesis and closing of flowers . Flowers of the three fo rms were collected in the field , analyzed by stereomicroscope, and measurements of the f loral pieces were made with the help of a caliper . Transversal and paradermal sections of the leaves of the three forms were stained and then examined under an optical microscope. Observations of the epidermis under scanning electron microscopy were also conducted. The three m orphotypes could not be sepated based on all evidence investigated. Thus, we conclude that there is not evidences to support the recognition of C. zonatus morphotypes as taxonomic entities, and also that the tools of phenology, anatomy, biology and floral morphology were not useful to delimit these three forms . Yet to characterize better the Flora of Bromeli aceae of RN, the leaf anatomy of Orthophytum disjunctum was also studied. Orthophytum is the sister genus to Cryptanthus and only recently documented in the semiarid of RN. The anatomical comparison between Cryptanthus and Orthophytum allowed the separatio n of both genera based on the arrangement of stomata and thickness of aquiferous parênquima . During the fieldwork, it was still possible to document the first occurrence of Aechmea muricata in RN, inside the Mata Estrela preserve, aiding the understanding of the distribution of the taxon that is currently threatened with extinction.
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v. 13, n. 2, p. 82-92, 2016.
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The identification of genotypes for drought tolerance has a great importance in breeding programs. The aim of this study was to characterize genotypes of beans in response to drought tolerance in different reproductive stages through physiologic, agronomic and molecular analysis. The experiment was conducted in greenhouse, using a randomized block design with four replicates; 10 cultivars: ANFC 9, ANFP 110, BRS Esplendor, BRSMG Realce, IPR Siriri, IPR Tangará, IPR Tuiuiu, IPR Uirapuru, IAC Imperador and IAC Milênio under two conditions of irrigation: plants irrigated during their entire life cycle, and plants under irrigation suppression in the reproductive stage (R7) until 16% of field capacity, when the irrigation was restored. In the last four days of stress, the gas exchanges were analyzed, and in the last day of stress was analyzed the percentage of closed stomata in the abaxial surface of the leaves, collected in different times of the day (9h, 12h, 15h and 18h). Additionally, plant samples were collected for the following analysis: fresh and dry mass of leaves, stems and legumes, and proline content in leaves and roots. The plants were harvested at the physiological maturity and the yield components and grain yield were determined. In addition, in order to identify polymorphisms in the sequences of promoters and genes related to drought, seven pairs of primers were tested on the group of genotypes. The drought susceptibility indexes (ISS) ranged from 0.65 to 1.10 in the group of genotypes, which the lowest values observed were for IAC Imperador (0.65) and BRS Esplendor (0.87), indicating the ability of these two genotypes to maintain grain yield under water stress condition. All genotypes showed reduction in yield components under water stress. IAC Imperador (43.4%) and BRS Esplendor (60.6%) had the lowest reductions in productivity and kept about 50% of the stomata closed during all the different times evaluated at last day of irrigation suppression. IAC Imperador showed greater water use efficiency and CO2 assimilation rate under drought stress. IPR Tuiuiú, IPR Tangará and IAC Imperador had the highest proline concentrations in the roots. Under water stress condition, there was a strong positive correlation (0.696) between the percentage of stomata closed with the number of grains per plant (0.696) and the fresh mass of leaves (0.731), the maximum percentage of stomata closed 73.71% in water stress. The accumulation of proline in the root was the character that most contributed to the divergence between the genotypes under water deficit, but not always the genotypes that have accumulated more proline were the most tolerant. The polymorphisms in DNA of coding and promoting sequences of transcription factors studied in this experiment did not discriminate tolerant genotypes from the sensitive ones to water stress.
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A seringueira é uma planta de fácil reconhecimento por ser lenhosa, de porte mediano a grande, que apresenta um padrão característico de desfolha e reenfolhamento e, sobretudo, pela produção de látex. O objetivo do trabalho foi efetuar um estudo anatômico e morfológico foliar, comparando os clones RRIM 600 e GT 1 de seringueira &91;Hevea brasiliensis (Wild. ex Adr. de Juss.) Muell.- Arg&93;, desenvolvidos sob as mesmas condições edáficas e climáticas, para obtenção de informações que possam fornecer subsídios para correlações com dados fisiológicos e também diferenciar os clones em relação ao conteúdo de fibras, espessamento de tecidos do parênquima paliçádico e do parênquima lacunoso, caracterização anatômica do pecíolo, número e tamanho de estômatos e fornecer dados referentes a morfologia foliolar. Foram realizadas secções transversais na região do mesófilo, nervura central e pecíolo, seguindo-se os métodos usuais de preparação de lâminas permanentes. Foram realizadas análises biométricas de extensões de tecidos dos parênquimas paliçádico e lacunoso e contagem do número de células do parênquima lacunoso. Paralelamente foram realizadas análises biométricas para aferições de estômatos. Não houve diferenças para a altura das células epidérmicas, altura e número de camadas do parênquima lacunoso e para o comprimento e para a maior largura do limbo foliolar. Porém houve variação para a espessura das células do parênquima paliçádico, sendo que GT 1 apresentou maior espessura em relação a RRIM 600. GT1 apresentou maior número de estômatos em relação a RRIM 600, porém com menor tamanho. GT1 apresentou maior diâmetro da nervura central da folha e do pecíolo e maior quantidade de fibras de esclerênquima que RRIM 600.
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A família Annonaceae possui 112 gêneros, dentre os quais encontra-se Annona, cuja espécie mais comum é a Annona muricata, conhecida popularmente como graviola. Possui fruto comestível de valor comercial e é rica em compostos bioativos que apresentam atividades antitumorais, antifúngicas, entre outros, tanto nos frutos como nas sementes, folhas e caule. Dentre os principais metabólitos encontrados estão os compostos fenólicos, óleos essenciais e as acetogeninas, citada como uma alternativa para o desenvolvimento de drogas antitumorais. Este trabalho visou à caracterização de aspectos morfoanatômicos das folhas de Annona muricata, a fim de investigar caracteres de secreção e ou armazenamento de substâncias lipídicas indicadas como uma das responsáveis pela ação farmacológica da espécie empiricamente. As amostras foram coletadas na área de plantio da Embrapa Amazônia Oriental, Belém-Pará. As folhas foram divididas em ápice, meio e base e confeccionados cortes histológicos semipermanentes, a mão livre, seguindo metodologia específica para detecção de substâncias lipídicas. Os testes deram positivos nos tecidos das células-guardas e subsidiárias dos estômatos, nos tricomas, epiderme abaxial, parênquima paliçádico e nervura central. Considerando que as acetogeninas são derivadas de ácidos graxos, pode-se inferir que estão presentes na maioria dos tecidos foliares de A. muricata. A análise qualitativa pode orientar a determinação de novas metodologias de extração do princípio ativo