Antioxidative potentials as a protective mechanism in Catharanthus roseus (L.) G.Don. plants under salinity stress

Antioxidant responses were analysed in Catharanthus roseus (L.) G.Don. under 0, 50 and 100 mM NaCl in order to investigate the plant's protective mechanisms against long-term salt-induced oxidative stress. The NaCl treatments were repeated in 4 different stages of growth, i.e. 30, 45, 60 and 75 days after sowing (DAS). The plants were uprooted randomly 90 DAS and the non-enzymatic and enzymatic antioxidant potentials were analysed. High salinity caused a decrease in reduced glutathione (GSH) and an enhancement in total ascorbate (AA) content and the antioxidant enzyme and ascorbate peroxidase (APX, EC 1.11.1.11) activities. Moreover, salinity induced a significant decline in superoxide dismutase (SOD, EC 1.15.1.1) and peroxidase (POX, EC 1.11.1.7) activities. The changes found in catalase (CAT, EC 1.11.1.6) activities may be of great importance in the H₂O₂ detoxification mechanism under oxidative stress.