The response of the xerophytic plant Gypsophila aucheri to salt and drought stresses: the role of the antioxidant defence system

The aim of the present study was to determine the antioxidant system responses of a xerophytic plant to salinity and drought, which were not elucidated before. Physiological and antioxidant responses of the xerophytic plant Gypsophila aucheri Boiss. were investigated under salinity (100 and 300 mM NaCl) and drought (withholding watering) treatment for 2 weeks in a controlled growth chamber. Besides growth responses (relative growth rate (RGR)), superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), and glutathione reductase (GR) activities, and SOD and CAT isoenzymes activities were determined under stress conditions. Moreover, the level of lipid peroxidation was determined as thiobarbutiric acid reactive substances (TBARS) content. Tolerance of G. aucheri to salinity and drought was evaluated based on lipid peroxidation (oxidative damage) and RGR. According to the experiments, G. aucheri was found to be tolerant to drought and 100 mM NaCl and its antioxidant system was able to cope with oxidative stress under these conditions. However, 300 mM NaCl treatment had detrimental effects on plant growth and membrane integrity. Under this concentration, oxidative stress cannot be precluded in spite of increased SOD, PDX, and APX activities. These data indicate that xerophytic G. aucheri is a moderate halophytic plant that uses an efficient antioxidant defence mechanism under salinity.