Suchergebnisse

With the increase of glyphosate tolerant transgenic soybean cultivation areas, this substance has become the main herbicide for this crop, its use may interfere in the metabolism and nutritional aspects of transgenic plants. In this scenario, the objective of this work was to verify concentrations of amino acid valine and in glyphosate tolerant soybean cultivar. Comparing the averages between protein and total amino acid levels in transgenic soybean exposed and not exposed to glyphosate, it was found that there was no significant difference by Tukey test at 5% probability. In conclusion, the data indicate that although the transgenic event affects some routes, amino acid synthesis was not affected nor in nutritional terms at the glyphosate doses studied.

Over the last few decades, the concentration of cadmium (Cd) in the environment has increased considerably in many countries due to anthropogenic activities. Cd is one of the most toxic pollutants in the environment and affects many metabolic processes in plants. The main objective of this study was to evaluate the response of the production, nutritional, and enzymatic antioxidant system of two tomato genotypes (Calabash Rouge and CNPH 0082) grown in tropical soils that were treated with doses of Cd. Soil samples were collected from the layer of earth at a depth of 0–0.2 m in areas subjected to a minimum of human disturbance. The concentrations of Cd applied to the soil samples were 0, 1, 2, and 4 times (0, 3, 6, and 12 mg kg−1 of Cd) the agricultural intervention value adopted by current environmental legislation in the state of São Paulo, Brazil. Analysis of superoxide dismutase, catalase, glutathione reductase, guaiacol peroxidase, and ascorbate peroxidase activities, formation of stress indicator compound (malondialdehyde—MDA and hydrogen peroxide), parameters of production—dry mass of the shoot and root system (here in after "shoots" and "roots"), as well as nutrition, and both the bioavailable and total levels of this metal in the soil were performed. When the bioavailable content and total levels of Cd in the soil increased as a result of this metal doses applied, the biomass of both shoots and roots decreased in both genotypes (with the exception of the CNPH 0082 grown in clay soil) and displayed lower SPAD (relative chlorophyll index) values when exposed to contaminated environments with Cd concentrations. Cadmium treatment resulted in nutritional imbalances, mainly in terms of N, P, and Mn metabolism. Plants subjected to an elevated available content of metal in the soil exhibited increases in content of MDA and hydrogen peroxide and increased activity of catalase, ascorbate peroxidase, and guaiacol peroxidase in plant tissues when grown in both clay soil and sandy soil. Cadmium was phytotoxic to the plants causing a nutritional imbalance, especially on the metabolisms of N, P, and Mn. An oxidative stress condition was established in response to the Cd treatments applied, which led to changes in peroxidase activity.

Brazilian Federal Government Agency ; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) ; Research Foundation Flanders - FWO ; CAPES: 1332394 ; Processo FAPESP: 2014/16731-7 ; Processo FAPESP: 2014/18735-0 ; Processo FAPESP: 2015/21562-2 ; Processo FAPESP: 2017/12367-7 ; Exposure to cadmium (Cd) can cause oxidative stress and injuries to the photosynthetic apparatus of plants. Otherwise, plant metabolism impaired by Cd toxicity can be aided by a proper sulfur (S) nutrition, since S is a component of antioxidants and photosynthetic systems. In this sense, our aim in this study was to evaluate the effect of S supply (0.1, 1.9 and 3.7 mmol L-1) on the antioxidant and photosynthetic systems of Massai grass exposed to Cd (0.0, 0.1 and 0.5 mmol L-1) as a prerequisite for studies of Cd phytoextraction. Plants supplied with 3.7 mmol L-1 S showed the lowest growth and the highest Cd concentrations when exposed to 0.5 mmol L-1 Cd. However, Massai grass grown without S deprivation showed the highest GSH + GSSG concentrations in all tissues and the lowest lipid peroxidation in stems and sheaths and roots. In general, the activities of SOD, CAT, APX, GPOX and GR did not increase in Massai grass exposed to Cd, even with proper S supply. Severe Cd exposure halted the photosynthetic system of Massai grass, although well-nourished plants with S exhibited greatest photosynthetic rate probably due to the action of GSH in the control of the oxidative stress.