Abstract: It is of great significance to study the effects and mechanisms of selenium (Se) in plant, because Se can do benefit to plant. The antioxidant system includes antioxidant enzymes and molecular antioxidant substances. This paper summarized research achievements at home and abroad, and reviewed the related research progress in this field. The researches at home and abroad found that the suitable concentration of Se could enhance the antioxidant capacity of plants and decrease the content of MDA, while excessive Se could aggravate the oxidative damage of plants. Therefore, the effects of Se on plant had two sides. This paper summerized the mechanisms of Se on the antioxidant system of plants included adjusting the content of active oxygen free radicals, transforming the form of Se, inserting into the iron sulfur cluster which affects the electron transport chain, repairing the cell membrane structure and cell integrity, recoverying photosynthesis and regulating the content of essential elements (cofactor). This paper was expected to provide references for the futher study of the effects of Se on resistance to abiotic stresses.

Key words: selenium, antioxidant, radical, mechanism, prospect

摘要： 硒是植物的有益元素，研究植物中硒的作用和机制具有重要意义。植物的抗氧化系统包括抗氧化物酶和小分子抗氧化物质。国内外研究发现添加适宜浓度的外源硒可以增强植物抗氧化能力、降低丙二醛（MDA）含量，而过量的硒则会加重植物氧化损伤。因而，硒对植物表现出两面性。综述了硒对植物抗氧化系统的作用机制包括调节活性氧自由基的含量、硒的形态转化、插入铁-硫簇影响电子传递链、修复细胞膜结构和细胞完整性、恢复光合作用、调节必需元素（如辅酶因子）含量等的研究进展，以期为深入开展硒抗非生物胁迫研究提供参考。

关键词: 硒, 抗氧化, 自由基, 机制, 展望