Nitric Oxide Acting as A Downstream Signaling Molecule of H2O2 Regulates Cd Tolerance in Brassica var. pekinensis

Abstract: Hydrogen peroxide (H2O2) and nitric oxide (NO) acting as a endogenous signal regulate and respond to a variety of biotic and abiotic stresses including cadmium (Cd) stress in plants. In this study， the interaction between H2O2 and NO in Chinese cabbage (Brassica var. pekinensis) under Cd stress was investigated with physiological and biochemical method. The results indicated that the seedlings pretreated with H2O2 exhibited enhanced tolerance to Cd stress， including the decreasing of malondialdehyde (MDA) concentration， the reduction of electrolyte leakage， the increasing of the nitric oxide synthase (NOS) activity and the raising of endogenous NO content. In parallel， the very similar results were shown when the seedlings were pretreated with sodium nitro prusside， a donor of exogenous NO. It was further verified with pharmacological experiments that the enhanced tolerence to Cd stress in seedlings pretreated by H2O2 was dramatically repressed by NO scavenger and inhibitor.Accordingly， it is concluded that the enhanced tolerance to Cd by H2O2 in seedlings highly depended on the endogenous NO signaling， which is fulfilled by enhancement of NOS activity with the application of H2O2.

CSTR: 32200.14.cjcb.2016.01.0008