David, Maria ManuelaBarrote, IsabelCorreia, Maria João2012-04-142012-04-142006David, Maria Manuela; Barrote, Isabel; Correia, Maria João. Influence of nutrient availability on drought-induced changes in the activity of antioxidant enzymes in sunflower leaves. Trabalho apresentado em VIII Simposium Hispano Portugués de Relaciones Hídricas en las Plantas. In Actas del VIII Simposium Hispano-Portugués de Relaciones Hídricas en las Plantas, Puerto de la Cruz, 2006.84-690-0174-4AUT: MDA00369; IBA00639; JCO00381;http://hdl.handle.net/10400.1/1031We aimed to evaluate if plants with different nutrient availability evidenced a different capacity to overcome drought-induced oxidative stress. Membrane peroxidative damages as MDA concentration and the activity of several antioxidant enzymes were determined in leaves of well watered (WW) and water stressed (WS) H. annuus plants grown either with adequate (Adeq Nutr) or limited (Limit Nutr) nutrient regimes. Constitutive capacity to eliminate ROS was not overall changed by growing plants with different nutrient supply regimes, but a diverse enzyme-dependent response was observed. In response to drought SOD and DHAR activity increased only in plants with limited nutrient supply, while in plants with adequate nutrient supply the activity of these enzymes did not change and were constitutively higher, but the activity APX increased by 50%. The subtle observed changes in the activity of the antioxidant enzymes are discussed, given that no oxidative damage was observed.engStress hídricoHelianthus annuusStress oxidativoDeficiência em nutrientesconference object2012-04-13