Keywords: 
• ozone /
• plants /
• antioxidant system /
• stress /
• regulation

Abstract: As a result of the rapid development of industry and agriculture, the concentration of global tropospheric ozone (O₃) is increasing continuously, which has detrimental influence on animals, plants and microbes in terrestrial ecosystem, as well as is harmful to human health. Effects of O₃ on plants especially on crops which relate to food safety have recently been increasingly reported. Ozone enters plant tissue through the opening stomata, and induces plant to produce active oxidant species (AOS), such as hydrogen peroxide (H₂O₂), superoxide (O₂^-·), hydroxyl radicals (·OH) and etc., which can damage membrane system of plant and reduce net photosynthesis. At the same time plants have the ability to scavenge AOS through closing the stomata to reduce the input of O₃ or increasing the activities of the antioxidant enzymes and the content of non-enzymatic, which enhance plant defending O₃ stress. Non-enzymatic, including ascorbic acid, carotenoid, some low molecular thiol-containing compounds (such as glutathione) and etc., can scavenge AOS through some chemical reactions. Ascorbic acid can remove AOS by reacting with superoxide, single oxygen, ozone and hydroxide. Carotenoids are effective in scavenging AOS to protect chlorophyll from ozone damage.As an important part of ascorbic-glutathione system,glutathione plays an important role in scavenging AOS.Antioxidant enzymes,including superoxide dismutase(SOD),peroxidase(POD),catalase(CAT),ascorbate peroxidase(APX),dehydroascorbate reductase(DHAR),and monodehydroascorbate reductase(MDAR)also play an important role in scavenging AOS.The mechanism of the O₃-induced damage to plant and their antioxidant system is complicated.On the basis of the summation of antioxidant mechanism of plants under ozone stress,some problems and suggestions are discussed in this paper.