Study On Heavy Metals' Accumulation Of Alternanthera Philoxeroides Transformed With MT Gene

Alternanthera philoxeroides,which has a high degree of evolution plant undergoing the long-term artificial and natural selection,widely distributes in the world especially in fresh water.Compared with other plants,it has strong resistance ability to adversity and rapid growth besides a wide range of adaptability and strong vitality.The concentration of tolerance and adsorption to heavy metals is high.Mammalian Metallothionein(MTs) are a sort of low-molecular-weight,thiol-rich and metal-binding proteins,which mainly function as detoxifying agents and in essential metals metabolism.Mouse MT has two different domains,αandβ,which not only have independent structures and function but also differ in metal-binding favors. Waste water containing heavy metals discharged far more than ever before with industrialization,urbanization.Although the concentration of heavy metals is very low, it can also seriously affect people's production and daily life.Genetic engineering and other biologically technical means can be used in transferring the accumulation-related factor into the good,non-edible plants in order to enhance or improve the biological characteristics of tolerance and absorption ability to heavy metals.To provide a scientific effective method of phytoremediation,this study is mainly on the degree of tolerance and accumulation of heavy metals of transgenic Alternanthera philoxeroides.The author carried out the following work.First,heretiary capicity of transgenic Altemanthera philoxeroides was valued,and MT gene in transgenic Alternanthera philoxeroides is determined with PCR test.36 in 45 reproduced plants were positive when sampled randomly.The result showed that the metallothionein gene in this kind of plant has a stable progeny in some extent.Torlerance tests of cadmium and mercury of transgenic Alternanthera philoxeroides are as follows:Transgenic trial materials and the sterilized plants directly from nature as control, were transplanted into MS medium containing different concentrations of mercury and cadmium.Then an observation of growth was carried out.The result shows that the transgenic plant significantly increased the tolerance of heavy metals.When compared the tolerance maximum concentration,the transgenic plant was higher.Studies on accumulation cadmium and mercury was implemented:the media containting different concentration of Cd²⁺ and Hg²⁺ designed according to the concentration of cadmium and mercury in pollution areas,are divided into two kind of concentrations.After half and a month,the concentrations of cadmium and mercury of the plants are determined with AAS and AFS respectivly.Then the data was analysed by Excel.When compared with the control plants,transgenic plant can absorb more heavy metals,transgenic Alternanthera philoxeroides can enhance and improve the capacity of absorpfing Cd and Hg.This transgenic plant can be considered as a practical and effective bioaccumulated ways to treat the environmental Cd and Hg contamination.