Research On Correlations Between Heavy Metal And Plant And The Regulative Role Of Polyamine

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...