Helianthus annuus L. responses to cadmium stress. Antioxidants as markers of the metal toxicity

M.D. GROPPA; M.P. BENAVIDES; M.L. TOMARO

Bariloche, Río Negro. Argentina

Congreso; XXXIX Reunión Anual SAIB. Annual Meeting SAIB, Protein Symposium; 2003

Sociedad Argentina de Investigación Bioquímica y Biología Molecular

Cadmium is an important environmental pollutant present in soils, toxic to living cells at very low and strongly phytotoxic. Cadmium toxicity was evaluated in relation to some antioxidant parameters, as antioxidant enzymes, polyamines (Pas) and proline in sunflower plants during the first 10 days of growth under 0.1 mM and 1 mM CdCl2. Plant growth and root length were significantly inhibited by the higher cadmium concentration from the third day. Except for guaiacol peroxidase, all the antioxidant enzymes (catalase (CAT), ascorbate peroxidase (APOX) and glutathione reductase (GR)) showed a significant increase under 1 mM CdCl2 from day 7 in shoots and roots, though in roots the rise in the enzymes activity was lower. Glutathione content also increased by day 7 in roots and shoots. Polyamines and proline increased from day 7 in shoots and roots under both cadmium concentrations. Thiobarbituric acid reactives substances (TBARS) measured as a marker of oxidative damage, was increased in roots and shoots only by 1 mM CdCl2. This increase was more extensive in roots than in shoots. Cadmium stress induced by the highest metal concentration produced an evident growth inhibition and oxidative damage, in spite of the increment of all of the measured parameters. The increase in polyamines and proline, postulated as antioxidants, offered an additional protection. However, other parameters, in addition to growth and oxidative damage, could add information about the exact magnitude of the damage exerted by the metal.