Response to oxidative stress induced by cadmium and copper in tobacco plants (Nicotiana tabacum) engineered with the trehalose-6-phosphate synthase gene (AtTPS1)
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The response of tobacco plants genetically engineered with the AtTPS1 gene to stress induced by excess Cu and Cd was evaluated in hydroponic solution (100 and 400 μM Cu and 50 and 200 μM Cd) after a 48 h exposure. Two transgenic lines, transformed with the AtTPS1 (trehalose-6-phosphate synthase) gene from Arabidopsis, with different levels of trehalose-6-phosphate synthase expression (B5H, higher and B1F, lower), and a wild type (WT) were investigated. Protein content, antioxidative enzymes (CAT, POD, SOD, and APX), glucose, fructose, lipid peroxidation, hydrogen peroxide and Cd and Cu contents were determined in leaves. The two transgenic lines were differently influenced by Cd and Cu exposure as they induced a different antioxidant enzymatic defense response. B1F and B5H plants showed a better acclimation to Cd and excess Cu compared to WT. Furthermore B1F was more tolerant than B5H to Cd and excess Cu. B1F accumulated less Cd and Cu in leaves, probably due to a more efficient exclusion mechanism. Catalase was shown to be the most important enzyme in the antioxidative system of these plants.
KeywordsAntioxidative enzymes Cadmium Copper Oxidative stress Tobacco
Author AM Almeida acknowledges funding from the FCT—Fundação para a Ciência e a Tecnologia (Lisboa, Portugal)—in the form of grant PRAXIS XXI/BD/21270/1999 that allowed the development of the transgenic plant lines and also a research contract by the Ciência 2007 program. This work was funded by Research Project PTDC/AGR-AAM/102821/2008—Plant responses to trace element toxicity: cellular mechanisms for detoxification and tolerance— and also by FCT. The UIQA (Unidade de Investigação Química Ambiental, Research Unit Environmental Chemistry) is grant aided by the FCT. The authors acknowledge the technical assistance of Maria do Céu Penedo in analytical determination of sugars and of Dulce Santos and Susana Araújo in the production of transgenic plants.
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