Effects of Ca(NO3)(2) stress on oxidative damage, antioxidant enzymes activities and polyamine contents in roots of grafted and non-grafted tomato plants

The effects of Ca(NO3)(2) stress on biomass production, oxidative damage, antioxidant enzymes activities and polyamine contents in roots of grafted and non-grafted tomato plants were investigated. Results showed that when exposed to 80 mM Ca(NO3)(2) stress, the biomass production reduction in non-grafted plants was more significant than that of grafted plants. Under Ca(NO3)(2) stress, superoxide anion radical (O-2 center dot(-)) producing rate, hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents of non-grafted plants roots were significantly higher than those of grafted plants, however, nitrate (NO3-), ammonium (NH4+) and proline contents, superoxide dismutase (SOD, EC1.15.1.1), peroxidase (POD, EC1.11.1.7), catalase (CAT, EC1.11.1.6) and arginine decarboxylase (ADC, EC 4.1.1.19) activities of grafted plants roots were significantly higher than those of non-grafted plants. Regardless of stress, free, conjugated and bound polyamine contents in roots of grafted plants were significantly higher than those of non-grafted plants. The possible roles of antioxidant enzymes, prolines and polyamines in adaptive mechanism of tomato roots to Ca(NO3)(2) stress were discussed.