【作者】 汤春芳；

【导师】 刘云国；

【作者基本信息】 湖南大学 ， 环境科学， 2005， 硕士

【摘要】 重金属是全球环境最重要的污染物之一,毒性强,难降解,不仅能通过活性氧和营养胁迫等的中介作用,导致植物氧化伤害、代谢紊乱,乃至死亡,并且能通过食物链富集危害人类身体健康。因此,研究植物重金属伤害及其抗性机理,已经成为有关环境和人类健康的重要问题。 多胺是一种抗氧化剂,具有调节生长发育、延缓衰老和提高植物的抗逆性等多重功能。研究多胺对重金属胁迫下植物生理生化作用的影响,可以为了解多胺缓解植物重金属伤害的机理、提高环境重金属污染的植物修复效率等提供参考依据。 对镉胁迫下萝卜幼苗水培实验的研究表明,镉胁迫能使O₂^-、H₂O₂和MDA的含量增加;抗氧化酶活性随处理所用的镉浓度和处理时间的不同而各异,在这些酶中,根系和叶片的GR活性的增加均与营养液所用镉浓度和处理时间正相关。 通过营养液栽培试验,研究外源Spd对Cd²⁺胁迫下宽叶香蒲叶片和地下茎中抗氧化系统生理指标的变化、镉的亚细胞分布、以及镉和微量营养元素的吸收和转运的影响。结果表明,单一镉处理（对照组）可以增加宽叶香蒲叶片和地下茎O₂^-、H₂O₂、MDA、GSH以及叶片AsA的含量;除叶片SOD活性下降外,叶片和地下茎中的CAT、GPX、GR和地下茎中SOD,以及叶片APX的活性都不同程度地升高。外源Spd可以进一步提高叶片和地下茎的GSH含量以及叶片AsA的含量、叶片和地下茎的GR和APX的活性以及地下茎的SOD、CAT、GPX活性,减少叶片和地下茎中O₂^-和MDA的产生,并且0.25 mmol/LSpd比0.50 mmol/LSpd对MDA含量增加的抑制作用更明显。无论是对照组,还是Spd处理组,宽叶香蒲吸收的Cd主要累积在根系,其次为地下茎、叶片;Cd在根系、地下茎和叶片的亚细胞分配次序均为:细胞壁>胞质>细胞器:外源Spd对Cd胁迫下宽叶香蒲对Cd以及微量营养元素的吸收和转运的影响依营养元素、植物组织、Cd以及Spd浓度的不同而各异,其中,Cd胁迫能增强宽叶香蒲根系Fe和Cu的含量,并且外源Spd的应用能促进这种增加。更多还原

【Abstract】 Heavy metal, one of the most important environmental contaminants which have extreme toxicity and can not be biochemically degraded, can induce plant oxidative damage, disturbance of metabolism, and even death owing to AOS and nutrition stresses and so on, and also threaten the health of human being through the food chain. So, it is quite important to study the mechanisms of heavy metal damage and tolerance of plants for the environmental safety and health of human being.PAs are antioxidants which possess multifunction, such as the regulation of growth and development, anti-senescence and anti-environmental stresses of plants. Investigation on the effects of exogenous PAs on physiological and biochemical functions of plants under heavy metal stresses can offer referenced evidence for the mechanism by which PAs ameliorate the damage to plants by heavy metal and improve the phytoremediation efficiency of heavy metal-contaminated water.When seedlings of radish were treated with Cd²⁺ in hydroponic system, increase in levels of the O₂^·一, H₂O and MDA was observed. Antioxidant enzyme activities responded differently to the content of Cd²⁺and time of treatment. Among these enzymes, positive correlation between the GR activity and content of Cd²⁺, and GR activity and time of treatment exisited in both leaves and roots.The effects of exogenous Spd on the antioxidant system under Cd²⁺ stress in Typha latifolia L. grown hydroponically were investigated. The results showed that Cd²⁺ increased the generation of O₂^·一 the H₂O₂ and MDA contents in both leaves and caudices. With the exception of SOD activity in the leaves, the activities of CAT, GPX and GR in both caudicies and leaves, and SOD activity in caudices whereas APX in leaves were increased following Cd²⁺ treatment. The GSH content in both caudicies and leaves and the As A content only in leaves was obviously increased, which were prompted by the application of Spd. Spraying with Spd increased the activity of GR and APX in both tissues, while the activity of SOD, CAT and GPX only in caudices. The generation of O₂^·一 and MDA contents in both tissues decreased by Spd. The decrease in MDA was more obvious following the application of 0.25 than 0.50 mmol/L Spd. In control and Spd treatment plants, the accumulation of Cd was mainly in roots, next caudices, and last leaves, and the subcellular distribution of Cd is uneven, following the order of cell wall > soluble fraction > cell organs. The effects of Spd on the uptake and translocation of Cd and other nutrient elements in T更多还原