Leaf lettuce matabolome during aging and under stress

• Autor(a) principal: Figueiredo, Patrícia Isabel Duarte de
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/8153
• topic: Biotecnologia; Alface - Envelhecimento; Pesticidas; Metabolismo vegetal; Ressonância magnética nuclear

The plant metabolome is extremely diverse due to the extraordinary variety of secondary metabolites. Nuclear magnetic resonance (NMR) spectroscopy techniques in metabonomics have been used for the identification of metabolite presents in plants under stress. The work reported in this thesis aimed to evaluate the metabolic and physiological changes that occur in lettuce leaves, caused by aging, light and dark growth conditions and due to exposure to mancozeb pesticide. Lettuces were grown during four weeks, and then separated in two groups in order to study the light/dark conditions and mancozeb pesticide exposure during growth. For the light/dark conditions study some lettuces were exposed during one week to a light intensity of 200 ± 20 μmol.m–2.s–1 (control), and others to 20 ± 20 μmol.m–2.s–1 (dark conditions). In the pesticide assay, the mancozeb was applied to a set of lettuces and not to the other (control). After one week, young leaves (from the first node) and expanded leaves (from the apical node) were collected. In general, the results show that the leaf age, the light/dark conditions and the exposure to mancozeb influence the plant physiological performance, such as pigment concentration and photosynthetic efficiency, as well as the plant metabolomic composition. The results show that young leaves show higher contents of glucose and sucrose, and lower contents of malic and citric acids than expanded leaves, and there was no significant differences in the physiological parameters measured. In the dark, the lettuce leaves present a decreased in the photosynthetic performance, which was more marked in expanded leaves compared to young leaves, resulting in significant decreases of glucose and sucrose on these leaves. Moreover, exposure of lettuce leaves with mancozeb resulted in decrease in photosynthetic performance, more marked in expanded leaves than in young leaves, with accumulation of glucose and decrease in some amino acids and several organic acids.