The involvement of hydrogen peroxide in polyamine-induced cell death in Nicotiana tabacum.

IANNONE M.F.; ROSALES E.P.; GROPPA M.D.; BENAVIDES M.P.

Villa Carlos Paz, Córdoba, Argentina

Congreso; XLIV Reunión Anual. Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2008

Polyamines (PAs) are ubiquitous in living organisms and have been implicated in a wide range of processes, including plant growth and development. It is suggested that they are involved in cell proliferation and cell death. The aim of this work was to evaluate the effect of exogenously added PAs in cell death events in tobacco. Leaf discs from 70-day-old wild type SR1 tobacco plants were treated for 2, 16 and 24 h with 0.1mM or 1mM Put, Spm or Spd. All PAs concentrations tested increased O2.- as well as H2O2, in a dose dependent manner, evidenced using nitrobluetetrazolium and diaminobencidine staining, respectively. Additionally, Spm was the most deleterious PA in relation to membrane damage, increasing Evans blue staining 10 times and electrolyte leakage 85% over the controls at 24 h of exposure. Previous addition of catalase (1500 U/ml) significantly reversed (50%) the increased in solute leakage in Spm-treated leaves, suggesting that H2O2 derived from Spm catabolism was the molecule involved in cell death. Chlorophyll content was not altered by any of the treatments whereas TBARS content, measured as an index of lipid peroxidation, was increased from 16h with 1 mM Put or Spm. These preliminary results suggest that H2O2 could be the main oxidant molecule involved in PAs toxicity, and this damaging effect could be partially prevented by catalase in the case of Spm.