Effects of exogenous nitric oxide and salicylic acid on chilling-induced oxidative stress in wheat (Triticum aestivum)

This study investigated the effect of pretreatments of nitric oxide (NO) and/or salicylic acid (SA) on alleviation of chilling stress in wheat (Triticum aestivum). Sodium nitroprusside (SNP) was used as the NO source. Eleven-day-old wheat seedlings were pretreated with 0.1 mM SNP and/or 1 mM SA for 12 h and then exposed to chilling conditions (5/2 degrees C day/night temperature) for 3 days. The rate of generation of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) and superoxide anion ( [GRAPHICS] ) significantly increased in chilling-treated compared with control plants. Similarly, malondialdehyde content increased in chilling-treated plants. SNP and/or SA significantly decreased the rate of H2O2 and [GRAPHICS] compared with only chilling-treated plants. Combined application of SNP and SA considerably reduced the rates of malondialdehyde, H2O2 and [GRAPHICS] in chilling-treated seedlings. SNP and/or SA increased the activity of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX), which contributed to ROS scavenging in wheat under chilling stress. The highest values for SOD, CAT and POX activities were observed in the combined application of SNP and SA under chilling stress. The results suggest that alleviation of chilling-stress induced oxidative damage was more efficient by the combined application of SNP and SA than by SNP or SA alone.