Alleviation of high salt toxicity-induced oxidative damage by salicylic acid pretreatment in two wheat cultivars

Role of exogenous salicylic acid (SA) in the antioxidative response to salt toxicity of two wheat (Triticum aestivum) cultivars (Gerek-79 and Bezostaya) was investigated. Hydroponic growth environment of 10-day wheat seedlings grown under normal conditions (22/20 degrees C) was adjusted to 0.0, 0.25, 0.50 and 0.75 M of salt (NaCl), and then freshly prepared SA solutions (0.0, 0.01 and 0.1 mM) were once sprayed on leaves of the same seedlings. Activities of superoxide dismutase (SOD), peroxidase (POX) and catalase (CAT) were determined in fresh leaves obtained from 15-day seedlings. Treatment with SA alone increased all the antioxidant activities in Gerek-79. However, the same treatments with SA decreased the activities of CAT and SOD in Bezostaya, while increased that of POX. Salt applications alone increased the activities of POX and SOD, while decreased that of CAT in Bezostaya. The same salt applications increased the POX activity, while decreased the activities of CAT and SOD in Gerek-79. In plants under saline conditions, except 0.75 M NaCl, treatments with SA increased the activities of CAT, POX and SOD in both the varieties compared with plants applied salt alone. In plants applied with 0.75 M NaCl, however, treatments with SA decreased CAT activity. Results showed that salt toxicity caused a derangement in the regulation of antioxidant enzyme activities by decreasing CAT activity especially in both the varieties, but treatments with SA could turn back the derangement in the antioxidative enzymes caused by salt toxicity. SA can involve in increasing salt tolerance by regulating the activities of antioxidant enzymes in wheat cultivars exposed to salt toxicity.