Scots pine as a model plant for studying the mechanisms of conifers adaptation to heavy metal action: 2. Functioning of antioxidant enzymes in pine seedlings under chronic zinc action

摘要

Functioning of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APO), and guaiacol peroxidases (GPO)) and low-molecular organic ROS scavengers (proline and phenolic compounds) in various organs (roots, cotyledons, stem, and needle) of 6-week-old seedlings of pine (Pinus sylvestris L.) developing in the chronic presence of ZnSO(4) (50, 100, and 150 mu M). Pine seedlings were grown in water culture in the climate-controlled chamber at an irradiance of 37.6 W/m(2) with a 16-h photoperiod, an air temperature of 23 +/- 1/15 +/- 1A degrees C (dayight), and a relative humidity of 55/70% (dayight). Endogenous Zn content was a key factor determining SOD activity decomposing superoxide into H(2)O(2) and O(2). Hydrogen peroxide produced is efficiently destroyed by CAT and also by APO and GPO. At the same time, the content of proline increased (especially at 150 mu M ZnSO(4)), but the content of phenolic compounds remained unchanged. All these processes help to maintain stable intracellular levels of O (2) (aS (TM) a') and H(2)O(2) at elevated zinc concentrations and to prevent generation of hydroxyl radical and development of oxidative stress.