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URI permanente desta comunidadehttps://thoth.dti.ufv.br/handle/123456789/3352
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Item Antioxidative responses of cell suspension cultures of two Coffea arabica varieties to low aluminum levels at pH 5.8(Instituto de Pesquisas Ambientais, 2012) Bottcher, Alexandra; Nobile, Paula Macedo; Martins, Paula Fabiane; Conte, Fábio Frangiotti; Azevedo, Ricardo Antunes; Mazzafera, PauloThe effects of aluminum (Al) on the activities of antioxidant enzymes and ferritin expression were studied in cell suspension cultures of two varieties of Coffea arabica, Mundo Novo and Icatu, in medium with pH at 5.8. The cells were incubated with 300 μM Al3+, and the Al speciation as Al3+ was 1.45% of the mole fraction. The activities of superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) were increased in Mundo Novo, whereas glutathione reductase (GR) and guaiacol peroxidase (GPOX) activities remained unchanged. SOD, GR, and GST activities were increased in Icatu, while CAT activity was not changed, and GPOX activity decreased. The expression of two ferritin genes (CaFer1 and CaFer2) were analyzed by Real-Time PCR. Al caused a downregulation of CaFER1 expression and no changes of CaFER2 expression in both varieties. The Western blot showed no alteration in ferritin protein levels in Mundo Novo and a decrease in Icatu. The differential enzymes responses indicate that the response to Al is variety-dependent.Item Behavior of coffee seeds to desiccation tolerance and storage(Associação Brasileira de Tecnologia de Sementes - ABRATES, 2014) Abreu, Luciana Aparecida de Souza; Veiga, Adriano Delly; Pinho, Édila Vilela de Resende Von; Monteiro, Fiorita Faria; Rosa, Sttela Dellyzette Veiga Franco daThe technology developed by breeding programs is applied to coffee seeds; however, after processing and drying, they lose viability within a short period of time, thus making storage unsuitable. The objective of this research was to evaluate the quality of coffee seeds submitted to different drying methods and moisture contents during storage. The coffee seeds were submitted to conventional drying (slow shade drying) and fast drying in a static drier until they reached a moisture content of 40, 20, 12 and 5%. After this process, the seeds were stored in a cold chamber for 12 months, and seed quality was evaluated before and during storage by the germination test, electrophoretic patterns of heat resistant proteins, and the activity of isoenzyme systems. Conventional drying (slow shade drying) at 20% of moisture content maintains coffee seed quality until 12 months of storage.Item Stomatal behavior and components of the antioxidative system in coffee plants under water stress(Escola Superior de Agricultura "Luiz de Queiroz", 2011-01) Deuner, Sidnei; Alves, José Donizeti; Zanandrea, Ilisandra; Goulart, Patrícia de Fátima Pereira; Silveira, Neidiquele Maria; Henrique, Paôla de Castro; Mesquita, Alessandro CarlosCoffee (Coffea arabica) plants show a positive relationship between stomatal closure and formation and accumulation of H2O2. However, for coffee plants under water restriction such relationship has never been studied. The objective of the present study was evaluate the stomatal movement and the antioxidant capacity of coffee seedlings under different water regimes. Eight months old coffee seedlings of cv. Catuaí IAC 99 were submitted to field capacity, gradual and total suspension of irrigation during a period of 21 days. Evaluations of leaf water potential (Ψ w) were performed in the beginning of the morning, and stomatal resistance, transpiration rate and vapor pressure deficit were determined at 10 am and 5 pm. All biochemical and enzymatic determinations were performed in leaves collected at 5 pm. Evaluations and samplings were performed at three days intervals. There was no variation in Ψ w during the evaluated period for plants in field capacity. However, an expressive decrease of Ψ w following day 12, reaching values near -2.5 MPa at the end of the experiment was observed for plants submitted to gradual suspension of irrigation. For plants submitted to total suspension of irrigation, Ψ w decreases after the sixth day, reaching -2.5 MPa at day 15. The decay of Ψ w in plants submitted to gradual and total suspension of irrigation reflected in increased stomatal resistance and in a decreased transpiration rate leading to an increase in hydrogen peroxide formation and, on final stages, increase in lipid peroxidation. As a conclusion, an increase in the activity of antioxidant enzymes as well as in the levels of ascorbate and dehydroascorbate was observed, which act in the detoxification of free radicals formed as result of the water stress.Item Magnesium in the dynamics of carbohydrates and antioxidant metabolism of coffee seedlings in two irradiance levels(Editora UFLA, 2018-07) Dias, Kaio Gonçalves de Lima; Guimarães, Paulo Tácito Gontijo; Furtini Neto, Antônio Eduardo; Faquin, Valdemar; Pádua, Eduane José de; Silveira, Helbert Rezende Oliveira deThe aim of this study was to verify the physiological impacts and the carbohydrate dynamics of Coffea arabica, seedlings subjected to increasing concentrations of magnesium (Mg) and two irradiance levels. Methods: The experiment was carried out in growth chambers with nutrient solution. The treatments were five concentrations of Mg (0, 48, 96, 192, and 384 mg L-1 ) and two irradiance levels (80 and 320 μmol of photons m-2 s-1 ). The coffee seedlings were under the treatments for 90 days. Results: The leaves with deficiency or excess of Mg exposed to the irradiance of 320 μmol of photons m -2 s-1 accumulated more carbohydrates than those exposed to 80 μmol of photons m 2 s-1 . The accumulation of carbohydrates in the leaves increased the activity of antioxidant enzymes due to the increased production of reactive oxygen species (ROS). Leaves exposed to 320 μmol of photons m-2 s-1 exhibited symptoms of scald by the sun caused by photo-oxidation. The scald was more intense in plants with abnormal concentrations of Mg. The antioxidant system of the coffee tree is closely relates to the Mg supply and irradiance levels. Concentrations of Mg between 48 and 96 mg L-1 functioned as a mitigating agent of oxidative stress under stressful conditions caused by high irradiance level.