Effects of elevated CO2 and O3 concentration on active oxygen metabolism and anti-oxidative enzymes activities in spring wheat.

【Objective】 The objective of this experiment is to reveal the effect mechanism of elevated carbon dioxide(CO2) and ozone(O3) concentration singly or in combination on plants reactive oxygen species(ROS) metabolism and anti-oxidative enzymes activities.【Method】 Open-top chambers(OTCs) were utilized to investigate the change of lipid peroxidation extent,ROS production rate,content and anti-oxidative enzymes activities in spring wheat(Triticum aestivum L.) leaves under elevated CO2 and O3 concentration singly or in combination treatments.【Result】 The results indicated that the elevated CO2 concentration at(550±20) μmol.mol-1 induced a decrease on relative electrical conductivity,content of malondialdehyde(MDA),superoxide anion() production rate,hydrogen peroxide(H2O2) content and a increase on the activities of superoxide dismutase(SOD),catalase(CAT),peroxidase(POD),ascorbate peroxidase(APX) in spring wheat leaves during the whole growth stage.While the elevated O3 concentration at(80±10) nmol.mol-1 showed the opposite effects,which resulted in higher relative electrical conductivity,MDA content,production rate,H2O2 content and lower activities of SOD,CAT,POD,APX in spring wheat leaves compared with the control.But under the combined treatment of CO2 and O3 at concentration of(550±20) μmol.mol-1+(80±10) nmol.mol-1,MDA content,production rate,SOD activity were higher in general compared with the control.While relative electrical conductivity,H2O2 content and the activities of CAT,POD,APX increased in the leaves of spring wheat.【Conclusion】ROS metabolism rates are restrained and anti-oxidative enzymes are enhanced by elevated CO2 concentration,which presents protective efficacy on springwheat.While elevated O3 concentration accelerates ROS metabolism rates and reduces anti-oxidative enzymes activities,which represents injured effects on spring wheat.In combination of elevated CO2 and O3 concentration,the beneficial effects of CO2 on spring wheat are more than compensating the negative effects imposed by O3 and the latter in its turn partly counteracted the positive effects on spring wheat of the former.