Effects of Ni on superoxide dismutase and glutathione reductase activities and thiol groups: a comparative study between Alyssum hyperaccumulator and non-accumulator species

Abstract

In this study we investigated the activities of superoxide dismutase (SOD), glutathione reductase (GR) and total thiol groups in two Ni hyperaccumulator species, Alyssum inflatum Nyárády and Alyssum bracteatum Boiss. & Bushe, and a non-accumulator species (Alyssum saxatile (L.) Desv.). Plants were exposed to different concentrations of Ni (0, 100, 300 and 500 μM for hyperaccumulators and 0, 10 and 20 μM Ni for the non-accumulator) in solution culture. The accumulation of Ni, the influence of Ni on dry biomass, and SOD, GR and total thiol activities were measured. The results showed a growth retardation effect by Ni in all plants. The activity of SOD strongly decreased with increase in Ni concentration in A. inflatum whereas the other Ni hyperaccumulator, A. bracteatum, showed less decrease. In contrast, a positive link between SOD activity and Ni concentrations was observed in shoots and roots of A. saxatile. The GR and total thiol activities were increased in the hyperaccumulator plants by increase in Ni concentration, but no changes were observed in A. saxatile. The results indicate that in hyperaccumulators, the accumulation of Ni could negatively affect some vital physiological processes.