臭氧污染胁迫下植物的抗氧化系统调节机制

工业和农业的快速发展导致近地层O3浓度不断提高,这对陆地生态系统的动物、植物、微生物和人类健康造成伤害。O3对植物的影响尤其是对农作物的影响将关系到世界粮食的安全生产。O3污染胁迫可诱导植物产生活性氧物质,破坏植物的膜系统,影响植物的光合作用等正常生理功能。植物在自然适应过程中,可形成一套抗氧化机制来缓解O3胁迫伤害。综述了国内外近年来有关O3胁迫下植物抗氧化系统调节机制的研究进展,包括植物通过调节体内的抗氧化酶活性和非酶类物质含量来缓解O3对植物伤害的机制。O3污染胁迫下植物可调节其叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、脱氢抗坏血酸还原酶(DHAR)和单脱氢抗坏血酸还原酶(MDAR)等抗氧化酶的活性。抗坏血酸(AsA)、类胡萝卜素(Car)和谷胱甘肽(GSH)等非酶类物质在清除O3胁迫产生活性氧方面具有重要的作用。另外,根据目前的研究进展,提出了一些需要继续深入探讨的问题。

Antioxidant Mechanism of Plants under Ozone Stress

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 mono-dehydroascorbate 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.}