Protein and Peroxidase Modulations in Sunflower Seedlings (Helianthus annuus L.) Treated with a Toxic Amount of Aluminium

Abstract

The aim of this study is to investigate the effect of aluminium treatment on peroxidases activities and protein content in both soluble and cell-wall-bound fractions of sunflower leaves, stems and roots. Fourteen-day-old seedlings, grown in a nutrient solution, were exposed to a toxic amount of aluminium (500 μM AlNO(3)) for 72 h. Under stress conditions, biomass production, root length and leaf expansion were significantly reduced. Also, our results showed modulations on soluble and ionically cell-wall-bound peroxidases activities. In soluble fraction, peroxidases activities were enhanced in all investigated organs. This stimulation was also observed in ionically cell-wall-bound fraction in leaves and stems. Roots showed a differential behaviour: peroxidase activity was severely reduced. Lignifying peroxidases activities assayed using coniferyl alcohol and H(2)O(2) as substrates were also modulated. Significant stimulation was shown on soluble fraction in leaves, stems and roots. In ionically cell-wall-bound fraction lignifying peroxidases were enhanced only in stems but severely inhibited in roots. Also, aluminium toxicity caused significant increase on cell wall protein content in sunflower roots.