Resumo em Português:
A despeito da importância da Artemisia annua L. como a única fonte da droga anti-parasitária artemisinina, muito pouco é sabido sobre o papel dessa molécula em plantas sob estresses biótico e abiótico. A deficiência hídrica é o principal fator limitante no crescimento vegetal, mas pode induzir a acumulação de metabólitos secundários, dependendo da intensidade e fase de desenvolvimento da planta. Plantas de A. annua cultivadas em câmaras de crescimento foram submetidas a cinco tratamentos (plantas irrigadas e com 14, 38, 62 e 86 horas sem irrigação). Deficiências hídricas de 38 e 62 horas (Yw = -1.39 e -2.51 MPa, respectivamente) aumentaram o conteúdo foliar de artemisinina, mas somente a deficiência hídrica de 38 horas induziu um aumento significativo da molécula em folhas (29%) e planta inteira, sem afetar o acúmulo de biomassa. Os outros tratamentos não afetaram significativamente o conteúdo de artemisinina. As plantas de A. annua apresentaram uma boa tolerância a deficiência hídrica, incluindo o tratamento mais severo (Yw -3.97 MPa ou 86 h sem irrigação) e recuperaram a pressão de turgor após a reidratação. Estes resultados sugerem que uma deficiência hídrica moderada imediatamente antes da colheita de A. annua pode não somente reduzir o tempo e os custos de secagem da cultura, mas também induzir ao acúmulo de artemisinina, condições que, conjuntamente, são benéficas para o cultivo commercial da espécie. Finalmente, estes resultados sugerem que a artemisinina pode ser parte do sistema químico de defesa da A. annua contra a deficiência hídrica.Resumo em Inglês:
Despite the importance of Artemisia annua L. as the only source of the anti-parasitic drug artemisinin, little is known on the effects of biotic and abiotic stress on artemisinin accumulation. Water deficit is the most limiting factor on plant growth, however it can trigger secondary metabolite accumulation, depending on the plant growth stage and intensity. A. annua cultivated in growth chambers was submitted to five water deficit treatments (watered, 14, 38, 62 e 86 hours without irrigation). Water deficits of 38 and 62 hours (Yw = -1.39 and -2.51 MPa, respectively) increased leaf artemisinin content, but only 38 hours led to a significant increase in both leaf and plant artemisinin (29%), with no detriment to plant biomass production. The other treatments had no effect on, or decreased artemisinin accumulation. A. annua plants tolerated well water deficit treatments, including the most severe water deficit applied (Yw -3.97 MPa or 86 hs without irrigation) and recovered their turgor pressure after rehydration. These results suggest that moderate water deficit prior to harvesting the crop may not only reduce time and costs in drying the crop, but can also induce artemisinin accumulation, both of which increase crop profit margins. Results also suggest that artemisinin could be part of A. annua chemical system of defense against water deficit.Resumo em Inglês:
In this study, proteins extracted from laticifer cells of three plants were examined by electrophoresis, mass spectrometry (MALDI-TOF) and characterized in respect of proteolytic, chitinolytic and anti-oxidative activities by means of zymography and colorimetric assays. Acidic proteins with molecular masses between 12.5 and 74.5 kDa predominated in laticifers of P. rubra. This profile was not found in laticifers of C. grandiflora and E. tirucalli. The later was poor in respect of proteins. Strong anti-oxidative activity of superoxide dismutase (E.C. 1.15.1.1) was detected in P. rubra and C. grandiflora latices, and to a lesser extent ascorbate peroxidase (E.C. 1.11.1.1) and isoforms of peroxidase were seen. Catalase (E.C. 1.11.1.6) was detected only in laticifer cells of C. grandiflora. Chitinase (E.C. 3.2.1.14) was the sole activity found in laticifer cells of E. tirucalli, but was also detected in the other latices. The strong proteolytic activity of C. grandiflora was shown to be shared by at least three distinct cysteine proteinases (E.C. 3.4.22.16). Serine, aspartic and metaloproteinases were not detected. In laticifer cells of P. rubra, four proteinases were detected, including cysteine and serine types. This study reports new protein data of laticifers from plants that have been poorly investigated in this respect and contributes to the understanding of biochemical and functional aspects of laticifers in plants.Resumo em Português:
O objetivo deste trabalho foi a caracterização dos perfis protéicos expressos durante o desenvolvimento da semente de O. catharinensis, uma espécie recalcitrante, via eletroforese bidimensional. A extração de proteínas foi realizada utilizando tampão uréia/tiouréia seguido de uma etapa de precipitação com TCA 10%. A análise comparativa durante o desenvolvimento da semente mostrou um grande número de proteínas exclusivas em cada estádio do desenvolvimento. O estádio cotiledonar, que representa a fase de transição entre a embriogênese e o começo do metabolismo relacionado a maturação, apresentou o maior número de proteínas estádio-específicas. Proteínas relacionadas ao metabolismo oxidativo e a síntese de reservas foram identificadas via MS/MS. Estes resultados contribuem para o melhor entendimento do metabolismo de proteínas durante o desenvolvimento de sementes recalcitrantes, além de prover informações no estabelecimento de parâmetros para protocolos de embriogênese somática.Resumo em Inglês:
The aim of the present work was to characterize changes in the protein profile throughout seed development in O. catharinensis, a recalcitrant species, by two-dimensional gel electrophoresis. Protein extraction was undertaken by using a thiourea/urea buffer, followed by a precipitation step with 10% TCA. Comparative analysis during seed development showed that a large number of proteins were exclusively detected in each developmental stage. The cotyledonary stage, which represents the transition phase between embryogenesis and the beginning of metabolism related to maturation, presents the highest number of stage-specific spots. Protein identification, through MS/MS analysis, resulted in the identification of proteins mainly related to oxidative metabolism and storage synthesis. These findings contribute to a better understanding of protein metabolism during seed development in recalcitrant seeds, besides providing information on established markers that could be useful in defining and improving somatic embryogenesis protocols, besides monitoring the development of somatic embryos in this species.Resumo em Inglês:
With Japonica rice BRS Firmeza and indica rice BRS Pelota (low and high grain yield, respectively) as materials, Chl content and Chl a fluorescence parameters in flag leaves from the heading to mature grain stage were investigated. The Chl content and the Chl a fluorescence were measured using a portable chlorophyll meter CL-01 and portables fluorometer Handy-PEA and FMS-2 (Hansatech, Kings Lynn, UK), respectively. All measurements were taken on middle part of the flag leaves (n = 10). The results showed that the Chl content and Chl a fluorescence parameters declined after full expansion of flag leaves in both rice cultivars. However, these biochemical and photochemical parameters did not show similar changing pattern and the behavior of flag leaves senescence showed some differences between BRS Pelota and BRS Firmeza rice cultivars. During the senescence of flag leaves, BRS Pelota, the rice cultivar with higher grain yield capacity, was characterized by significant reductions in Chl content, PI ABS,Total, TR0/ABS, ET0/ABS, ET0/TR0, RC/ABS compared to BRS Firmeza. On the other hand, DI0/RC, TR0/RC and ET0/RC were significantly higher in BRS Pelota. These results show that the decreased photosystem II activity, evaluated through chlorophyll fluorescence analysis, was resultant of leaves senescence process, which was much more expressive in BRS Pelota rice variety. We suggest that the higher productivity of BRS Pelota rice cultivar results from its higher assimilate mobilization ability or energy usage efficiency, in despite of its lower light absorption capacity.Resumo em Inglês:
Soil salinity is a major limitation to crops production in many areas of the world. The present study reports the impact of salt stress on seeds germination, plant growth parameters and leaf ions accumulation in three cowpea Vigna unguiculata (L.) Walp Indian cultivars: Akshay102, Gomti vu-89 and Pusa Falguni. The electrical conductivity (EC) of the soil was 0.75 dS m−1 and the NaCl treatments increased it to 2, 4, 6, 8 and 10 dS m−1. Germination percentage was recorded 10 days after sowing, while shoot and root dry weights were measured in 45 days old plants. Leaf ion concentrations for Na+, K+, Ca2+, Cl− and proline content were determined. The results showed that the germination percentage of seeds was highly affected by salinity in all cultivars in all salinity levels from 2 to 10 dS m−1. On the other hand, height and weight of all cultivars were less affected by the salt stress. Only at 10 dS m−1 EC, significant reduction in plant height and root length could be found for all three cultivars. Salinity induced a significant increase in Na+, Cl− and proline concentrations, while reduced the accumulation of K+ and Ca2+ in leaves of all the cultivars. Moreover, the tolerance difference between the cultivars was better observed at the lowest levels of salt stress, as reveled in the measurements of K+/Na+ ratio and proline content. In conclusion, this study characterizes Akshay102 as the most tolerant cultivar and establishes the measurements of germination capacity, K+/Na+ ratio and proline accumulation as an important features to be explored in programs for selection and/or development of tolerant cultivars which make possible the utilization of waste saline water as well as the cultivation of vast areas of the tropical world affected by salinity.Resumo em Português:
As adaptações ecofisiológicas de aguapé (hiperacumuladora de metais) sob condições ambientais adversas ainda não estão totalmente elucidadas. Este trabalho avaliou pigmentos fotossintéticos e fluorescência da clorofila a em aguapé coletados em diferentes regiões (alto, médio e baixo) do rio Paraíba do Sul (RPS) e no rio Imbé, Brasil. Adicionalmente Mn, Fe, Zn, Cu, Pb e Ni foram quantificados na parte área e raízes. Ferro e Mn foram os elementos detectados em maiores concentrações em todas as amostras. Zinco e Cu foram detectados em maiores concentrações nas raízes de plantas do médio e alto RPS, locais de grande atividade antropogênica. As mais elevadas concentrações de quase todos os metais foram verificadas nas plantas do médio RPS. Com relação às adaptações fotossintéticas, plantas do médio e alto RPS mostraram as maiores concentrações de pigmentos fotossintéticos, assim como os mais elevados valores de Fv/Fm e Fv/F0. As avaliações fotossintéticas destas plantas sugerem que elas não estejam sob condições de estresse, mesmo nas regiões de grande atividade antropogênica. Correlação positiva foi observada entre quenching não-fotoquímico e carotenóides, sugerindo que a dissipação de energia na forma de calor seja uma estratégia para manter o funcionamento fotossintético fotoquímico estável, confirmado pelos valores de Fv/Fm. É possível que esta estratégia adaptativa seja eficiente como resposta de longo prazo, uma vez que na literatura esta não parece ser a via preferencial de adaptação a estresses de curto prazo, avaliados sob condições controladas.Resumo em Inglês:
The ecophysiological adaptations of water hyacinth (metal hyperaccumulator) under adverse environmental conditions are not yet clearly elucidated. This work evaluated photosynthetic pigments and chlorophyll a fluorescence in water hyacinth plants sampled in different regions (upper, middle and lower) of Paraíba do Sul river (PSR) and Imbé river, Brazil. Additionally Mn, Fe, Zn, Cu, Cr, Pb and Ni were quantified on the shoots and roots. Roots were the preferential site of metal accumulation. Cromium was not detected in the shoots. Iron and Mn were the elements detected in higher concentrations in all samples. Zinc and Cu were detected in higher concentrations in roots of plants from middle and upper PSR, sites of higher anthropogenic activity. The highest concentrations of almost all metals were verified in plants from middle PSR. Regarding photosynthetic adaptations, plants from middle and upper PSR showed the highest concentrations of photosynthetic pigments, as well as the highest values of Fv/Fm and Fv/F0. The photosynthetic performance of plants suggests that they are not under stress conditions, even in regions of higher anthropogenic activity. Positive correlation was observed among nonphotochemical quenching and carotenoids, suggesting dissipation of energy in the form of heat as an strategy to keep the stable photochemical photosynthesis functioning, confirmed by values of the Fv/Fm. It is possible that such adaptative strategy is efficient as a long term response to stress factors, once literature data suggest that this is not a preferential path for photosynthesis in stress circumstances under short time controlled conditions.Resumo em Português:
Monitoramento do final da fase in vitro de plântulas de Anthurium andraeanum. O estímulo à autotrofia em plântulas in vitro pode ser alcançado através de mudanças no meio de cultura, ou pela troca de tampas herméticas por tampas que permitam a troca de gases entre a cultura e o ambiente. Além disso, o uso de lâmpadas com distintos espectros de irradição tem propiciado bons resultados. Este trabalho foi conduzido com o objetivo de avaliar a ação isolada ou em conjunto de fatores que podem induzir a autotrofia em plântulas de A. andraeanum vc. Eidibel in vitro. 3 concentrações de sacarose foram usadas: 0, 15 e 60 mM e para cada concentração foram empregados frascos com ventilação (0,038 L.h-1) ou sem ventilação. Os frascos foram mantidos sob lâmpada fluorescente fria ou gro-lux. O final dos experimentos mostrou que o maior acumulo de massa seca da parte aérea ocorreu a 60 mM, sob ventilação e gro-lux, e os tratamento que acumularam menor massa seca de raízes foram 0 mM com ventilação e sob luz fria e 15 mM sem ventilação e luz fria. Em média, os tratamentos com o maior teor de sacarose no meio, 60 mM, sob lâmpada gro-lux, apresentaram as maiores concentrações de clorofila a, b e total, do que sob luz fria. Os níveis de açúcares solúveis totais (sacarose e açúcares redutores) mostraram passos do metabolismo de carboidratos nessas plantas, realçando os momentos em que a exigência por nutrientes foi maior, destacando-se o papel de dreno das plântulas.Resumo em Inglês:
Estimulation of autotrophy in in vitro plantlets could be achieved through changes in the culture medium, or by changing the traditional hermetic caps by one that could allow gas exchanges between the culture and the environment. Besides that, the use of lamps with distinct emission spectrum irradiaction has propitiated successful results. This work was carried out aiming to evaluate the either the combined or the single action of some factors that can induce autotrophy on in vitro A. andraeanum cv. Eidibel plantlets. 3 sucrose concentrations were used: 0, 15 and 60 mM and for each one, to kinds of flasks according to the cap ventilation: under (0.038 L.h-1) and without ventilation. Flasks were kept under cold light fluorescent lamps or under gro-lux lamps. At the end of the experiment showing the highest shoot dry mass treatment was 60 mM, under ventilation and gro-lux, and the treatment which accumulate root dry mass to a lesser extent were 0 mM with ventilation and cold light and 15 mM without ventilation and cold light. In average, treatments with higher sucrose content in the culture medium, that is, 60 mM, under gro-lux lamps, presented the highest chlorophyll a, b and total contents, than those under cold lamp. Steps of carbohydrates metabolism could be associated with the total soluble sugars (sucrose and reducing sugars) levels, highlighting the steps where nutrient requirements were higher, showing the role of the plantlets sink.Resumo em Português:
O presente trabalho analisa as mudanças na composição de ácidos graxos de vesículas de tonoplato de hipocótilos de Vigna unguiculata (L.) Walp induzida por estresse causado por baixas temperaturas. Plântulas em condição controle desenvolveram-se por 7 dias à temperatura de 25°C e as plântulas tratadas foram submetidas a 10 ou 4°C por 4 dias, 3 dias após a germinação a 25°C. O frio (10 ou 4°C) induziu um efeito inibitório no desenvolvimento das plântulas e esse efeito foi mais pronunciado a 4°C. Além disso, o grau de insaturação dos ácidos graxos nas vesículas de tonoplasto aumentou sob o efeito do frio, o que pode indicar um aumento da permeabilidade das vesículas da membrana vacuolar. Nossos resultados sugerem que plantas de V. unguiculata aumentaram o seu conteúdo de ácidos graxos insaturados bem como a razão entre ácidos graxos insaturados/saturados, como mecanismo de adaptação ao frio numa tentativa de manter a fluidez da membrana vacuolar.Resumo em Inglês:
The present study was undertaken to investigate the changes induced by chilling on fatty acid composition of tonoplast vesicles from hypocotyls of Vigna unguiculata (L.) Walp. The 7 day-old control seedlings were grown at 25°C while treated seedlings were submitted to low temperatures (10°C and 4°C) for 4 days after 3 days germination. The chilling stress resulted in a differential inhibition of plant growth at 10°C and 4°C. Following chilling at 10°C and 4°C, the rate of unsaturated to saturated fatty acids increased under chilling stress. Our results suggest that the increase of unsaturated fatty acids content as well as the higher rate unsaturated/saturate fatty acidsmight be used by V. unguiculata plants as an adaptation mechanism likely to maintain the vacuolar membrane fluidity under low temperatures.