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Brazilian Journal of Plant Physiology, Volume: 23, Número: 2, Publicado: 2011
  • Challenges in proteome analyses of tropical plants Mini Review

    Balbuena, Tiago S.; Dias, Leonardo L. C.; Martins, Mariana L. B.; Chiquieri, Tatiana B.; Santa-Catarina, Claudete; Floh, Eny I. S.; Silveira, Vanildo

    Resumo em Português:

    O sequenciamento dos genomas de diversos organismos tornou praticável a análise global da expressão gênica, fornecendo numerosas pistas quanto à função biológica e envolvimento de inúmeros genes nos processos biológicos estudados. A proteômica é um dos ramos da biologia molecular e da biotecnologia que passou por expressivo desenvolvimento na era pós-genômica. Apesar dos recentes avanços nas técnicas em proteômica, muito resta a ser aprimorado. Devido às particularidades do reino vegetal, várias abordagens devem ser adaptadas no sentido de aumentar a eficiência e a acurácia de resultados das análises proteômicas em plantas. Nesse sentido, os dados gerados pela proteômica podem contribuir substancialmente para a compreensão e acompanhamento de eventos fisiológicos e para o desenvolvimento de estratégias biotecnológicas. No que tange às espécies tropicais, as dificuldades são ainda maiores, devido ao fato de serem ricas em metabólitos secundários e ainda não terem seus genomas totalmente sequenciados. Esta revisão trata de tópicos atuais em estudos de proteômica de plantas, desafios e perspectivas, com ênfase em espécies tropicais.

    Resumo em Inglês:

    Genome sequencing of various organisms allow global analysis of gene expression, providing numerous clues on the biological function and involvement in the biological processes studied. Proteomics is a branch of molecular biology and biotechnology that has undergone considerable development in the post-genomic era. Despite the recent significant advancements in proteomics techniques, still there is much to be improved. Due to peculiarities to the plant kingdom, proteomics approaches require adaptations, so as to improve efficiency and accuracy of results in plants. Data generated by proteomics can substantially contribute to the understanding and monitoring of plant physiological events and development of biotechnological strategies. Especially for tropical species, challenges are even greater, in the light of the abundance of secondary metabolites, as well as of the lack of complete genome sequences. This review discusses current topics in proteomics concerning challenges and perspectives, with emphasis on the proteomics of tropical plant species.
  • Flowering and vegetative growth of olive tree submitted to pruning and paclobutrazol application Research Articles

    Cruz, Maria C. M.; Oliveira, Adelson F.; Oliveira, Dili L.; V. Neto, João

    Resumo em Português:

    Com o objetivo de avaliar o florescimento e o crescimento vegetativo da oliveira em plantas submetidas à poda e a aplicação do paclobutrazol foi conduzido um experimento em condições de campo com ocorrência de baixas temperaturas durante inverno. Plantas da variedade Grappolo 575, com dois anos de idade, foram submetidas a uma poda leve, retirando-se a dominância apical, antes da aplicação dos tratamentos, no mês de abril de 2009. Para a distribuição dos tratamentos, adotou-se o esquema fatorial 4×2, referente às quatro concentrações de paclobutrazol testadas e dois grupos de plantas, com e sem poda, em blocos casualizados com quatro repetições. As concentrações de paclobutrazol testadas não influenciaram no florescimento da oliveira. O crescimento vegetativo foi retardado até 60 dias após a aplicação do paclobutrazol. A poda estimulou a emissão de brotações vegetativas e reduziu o florescimento.

    Resumo em Inglês:

    This work focuses on the evaluation of flowering and vegetative growth of olive tree submitted to pruning and paclobutrazol application under field conditions with low temperatures during the winter. Two-years-old olive plant variety Grappolo 575, were submitted to light pruning, removing apical dominance, before treatments application. The treatments were organized in a 4×2 factorial scheme, respective to four PBZ concentrations tested: 0, 200, 400 and 800 mg L-1 of PBZ and two plants groups, with and without pruning, in randomized block with four replications. Paclobutrazol concentrations tested did not affect the olive tree flowering. The plant vegetative growth was reduced until 60 days after paclobutrazol application. Pruning resulted in stimulation of emission of vegetative shoots and reduction of flowering.
  • Environmental drivers of leaf phenology in trees of the tropical species Ficus obtusifolia Research Articles

    Ballestrini, Caín; Tezara, Wilmer; Herrera, Ana

    Resumo em Inglês:

    Vegetative as well as reproductive phenology of tropical trees frequently occur synchronously at the end of the dry season. It has been repeatedly observed on two individuals of the tropical species Ficus obtusifolia growing in Caracas that they lose their entire foliage in a period of 48 h during the dry season and renew it within the next 72 h. In order to gain knowledge on the mechanisms that govern leaf exchange in F. obtusifolia, we followed in these two individuals the seasonal changes in leaf and fruit phenology, water relations and environmental variables, and in another 25, phenology only. Although foliar exchange was always observed before the rainy season, it also occurred near the end of the rainy season. An increase in leaf turgor potential of mature leaves and a low sap flow velocity coincided with leaf fall. Foliar exchange in all 27 individuals, growing in locations with different elevation and, possibly, access to underground water, was bi-modal and occurred in a period of approximately one month around both equinoxes. The presence of fruits was also bi-modal, occurring after leaf renewal. The sequence of phenological events repeated itself in all the individuals studied, although with inter-annual and individual variations in date of foliar exchange. Leaf fall was independent of leaf water status and significantly correlated with, in decreasing order, day length, minimum air temperature, rainfall, maximum air temperature and total radiation. We conclude that in F. obtusifolia high nocturnal temperature, increasing daytime temperature and radiation, and low cloud cover apparently drove foliar exchange. Day length showed a strong correlation with leaf renewal possibly to due to the significant relationships between day length and environmental variables. Direct effects of day length alone were not evidenced, as foliar exchange took place during a long time-span around the equinoxes.
  • Water relations and some aspects of leaf metabolism of Jatropha curcas young plants under two water deficit levels and recovery Research Articles

    Arcoverde, Gabriela B.; Rodrigues, Bruno M.; Pompelli, Marcelo F.; Santos, Mauro G.

    Resumo em Português:

    A condutância estomática (g s), transpiração (E), conteúdo relativo de água (RWC), a atividade da superóxido dismutase (SOD), conteúdo foliar de malondialdeído (MDA), carboidratos solúveis (LCS), aminoácidos livres (FAA) e proteína total (TP) foram mensurados sob estresse hídrico moderado, severo e na reidratação em plantas jovens envasadas de Jatropha curcas L. em casa de vegetação. As plantas foram mantidas por 12 dias, sob três diferentes regimes hídricos: controle (bem hidratada), 50% da irrigação do controle (estresse moderado) e 25% (estresse severo), após a reidratação foram mensuradas no segundo e no quarto dia. Tanto o déficit moderado quanto o severo reduziram g s e E, no entanto, apenas o estresse severo reduziu o conteúdo de LCS, FAA e TP e aumentou a atividade da SOD (70%) e conteúdo de MDA (60%) em comparação com o controle (plantas bem hidratadas). Além disso, sob seca severa, as plantas apresentaram senescência foliar acentuada. Estes resultados mostram que apenas a seca severa diminuiu o metabolismo foliar e RWC, em plantas envasadas. No entanto, 48 h sob um estresse moderado é o suficiente para que o rígido controle estomático seja a principal barreira contra a perda de água. No quarto dia após a reidratação, as plantas sob uma seca moderada e severa ainda apresentavam uma g s e E reduzidas em ambas as épocas de avaliação.

    Resumo em Inglês:

    Stomatal conductance (g s), transpiration (E), relative water content (RWC), superoxide dismutase activity (SOD), malondialdehyde (MDA), leaf carbohydrate soluble (LCS), free amino acids (FAA) and total protein (TP) content were measured under mild and severe drought stress in young potted Jatropha curcas L. in the greenhouse. The plants were kept for 12 days under three different water regimes, control (well hydrated), 50% irrigation control (mild stress) and 25% (severe stress), after rehydration were measured on the second and fourth day. Both mild and severe stress decreased g s and E; however, only severe stress reduced LCS, FAA and TP content and increased SOD activity (70%) and MDA content (60%) compared with the control. Moreover, under these conditions the plants showed severe leaf senescence. These results show that only severe drought stress decrease foliar metabolism in potted plants. These results show that severe drought decreased metabolism and leaf RWC, in potted plants. However, 48 h under a moderate stress is enough to drive the stomatal control is the main barrier against water loss. Finally, in the fourth day after rehydration the plants under a moderate and severe drought even had a g s and E reduced in both evaluation periods.
  • Cadmium-induced oxidative stress and antioxidative enzyme response in water hyacinth and salvinia Research Articles

    Vestena, Silvane; Cambraia, Jose; Ribeiro, Cleberson; Oliveira, Juraci A.; Oliva, Marco A.

    Resumo em Inglês:

    The reactive oxygen species generation, lipid peroxidation and antioxidative enzyme response of water hyacinth and salvinia to Cd were evaluated. Cadmium was absorbed/accumulated mainly in the roots, but significant amounts also translocated to the leaves. No Cd effect on dry weight was detected, although toxicity symptoms were visible. Superoxide and H2O2 concentrations increased, in addition to lipid peroxidation in both species, especially in the leaves of salvinia. In general, antioxidative enzyme activities were reduced in both species following Cd treatment, especially in salvinia. Glutathione peroxidase (GPX, EC 1.11.1.9) activity decreased in water hyacinth but increased in salvinia. Glutathione S-transferase (GST, EC 2.5.1.18) activity increased in the leaves but decreased in the roots of both species. So, Cd induced ROS generation/accumulation, but the antioxidative enzymes were not able to combat the Cd-induced oxidative injury in these two species. Nevertheless, water hyacinth consistently showed a higher tolerance to Cd than salvinia.
  • Evaluation of hydration indexes in kale leaves Research Articles

    Calbo, Adonai G.; Ferreira, Marcos D.

    Resumo em Inglês:

    Hydration indexes are practical variables for quantifying plant water stress and can be useful for agronomic purposes. Three adapted hydration indexes based on relative water content, volumetric hydration, and leaf turgor pressure were evaluated in kale (Brassica oleracea var. acephala) leaf segments. Relative water content and volumetric hydration were measured in leaf segments after a water infiltration procedure with the aim of filling its large intercellular volumes (@18%v/v). The infiltration was done using a hydrostatic weighing procedure and with the aid of vacuum to fully hydrate the leaf segments. These two relative indexes were proportional to the transpiration-induced leaf water loss. The third index, turgor pressure, was measured with a Wiltmeter® instrument. Similarly, the turgor pressure was proportional to the leaf water loss, and it decreased from @310kPa in recently harvested leaves to zero in dehydrated leaves, after a total water loss of @23%. Turgor pressure was correlated with the other two hydration indexes using approximations of leaf volumetric elastic modules. Similar estimates were obtained because the decline between turgor pressure and the natural logarithm of these relative leaf hydration indexes was numerically similar (@900kPa). However, the volumetric hydration index seemed to be more suitable as a model, not only for being more concise but also because it showed a clearer biomechanical representation of the leaf water deficit effects.
  • The influence of processing and long-term storage on the antioxidant metabolism of acerola (Malpighia emarginata) purée Research Articles

    Oliveira, Luciana S.; Rufino, Maria S. M.; Moura, Carlos F. H.; Cavalcanti, Fabio R.; Alves, Ricardo E.; Miranda, Maria R. A.

    Resumo em Português:

    Este trabalho avaliou o efeito do processamento e do tempo de armazenamento sobre o potencial antioxidante e atividade de enzimas antioxidantes de polpa congelada de frutos de seis clones de aceroleira. Foram colhidas acerolas maduras dos clones BRS 235, BRS 236, BRS 237, BRS 238, II47/1 e BRS 152; a polpa foi processada, acondicionada em sacos plásticos de polietileno selados à vácuo e armazenada em freezer doméstico à -18 °C por 11 meses. Amostras de cada clone foram analisadas no dia colheita/processamento e a cada 30 dias quanto aos compostos bioativos antioxidantes, a atividade de enzimas antioxidantes e a atividade antioxidante total. As polpas de acerola apresentaram uma diminuição dos antioxidantes não enzimáticos e um aumento da atividade das enzimas antioxidantes, indicativo de um mecanismo compensatório entre antioxidantes enzimático e não enzimático. Na polpa de acerola, antocianinas e polifenóis estão fortemente correlacionados com o conteúdo de sólidos solúveis e de vitamina C, destacando os polifenóis como o principal contribuinte para a atividade antioxidante total. A polpa do clone II47/1 teve um excelente desempenho em relação ao potencial antioxidante e o melhor período de armazenamento à -18 °C seria de 150 dias, para todos os clones estudados.

    Resumo em Inglês:

    This study evaluated the effect of the processing and long-term storage on the antioxidant potential and activity of antioxidant enzymes of frozen purées from six acerola clones. Ripe acerolas from clones BRS 235, BRS 236, BRS 237, BRS 238, II47/1 and BRS 152 were harvested; the pulp was processed, packed in sealed polyethylene plastic bags and stored in a domestic freezer at -18°C for 11 months. Samples of each clone were analyzed on harvest/processing day and every 30 days after for bioactive antioxidant compounds, antioxidant enzyme activity and total antioxidant activity. Acerola purées presented a decrease of non-enzyme antioxidants and an increase of antioxidant enzymes activities, indicatives of a compensatory mechanism between enzymatic and non-enzymatic antioxidants. In acerola purée, anthocyanin and polyphenols are strongly correlated to soluble solids content and vitamin C seems a major contributor to total antioxidant activity. Clone II47/1 had an outstanding performance regarding the antioxidant potential of its purée and the best storage period at -18ºC would be 150 days, for all clones studied.
  • Jasmonic acid elicits oxidative defense and detoxification systems in Cucumis melo L. cells Research Articles

    Nafie, Eetezaz; Hathout, Tahany; Al Mokadem, Al Shyma

    Resumo em Inglês:

    This study investigated whether a jasmonic acid (JA) elicitation strategy developed in a conventional cell suspension culture could evoke melon resistance mechanisms, including secondary metabolite production. Twenty one day cultured melon cell suspensions grown in MS1 medium were supplemented with JA at the concentrations of 0.5, 5.0 and 10 µmol. Melon cultures were sampled 24, 48 and 72 h post elicitation to evaluate different defense related factors such as antioxidant enzymes, ascorbate metabolism and phenolic compounds. Results suggest that melon cells respond to JA reprogramming the primary and secondary metabolism which will result in melon plantlets with enhanced resistance against diverse stress conditions through the production of specific bioactive molecules. Jasmonic acid elicited melon cells exhibited enhanced oxidative enzymes activities and ascorbic acid, coumarin and p-coumaric amounts were found without growth retardation. Induced intracellular JA functions as a signal transducer acting upstream to H2O2, which is a secondary messenger triggering jasmonic signaling cascades by activating certain late genes that regulate the activity of catalase, peroxidase and de novo synthesis of five isozymes, ascorbic peroxidase detoxifying enzymes concomitant with ascorbate compound. Secondary metabolite production in melon cells seems to be activated upon JA exposure suggesting that this cell culture could be used as a source for rapid and increased production of coumarin, p-coumaric, ascorbic acid and likely other specific phenylpropanoids. These data provide further evidences for a role of jasmonic acid in the intracellular signal cascade that results in the accumulation of secondary compounds and ultimately induced melon resistance. This approach could assist further in understanding the metabolic mechanisms operating in melon cells under stress, and thus how to control them.
Brazilian Journal of Plant Physiology Centro de Ciências e Tecnologias Agropecuárias, , Universidade Estadual do Norte Fluminense Darcy Ribeiro - UENF, 28013-602 - Campos dos Goytacazes, RJ - Brazil, Fax: (+55)-22-2739-7116 - Campos dos Goytacazes - RJ - Brazil
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