The Characteristics Of Cd Adsorption And Uptake By Amaranth Root Under NaCl Salinity Stress

At present, a large area of farmland soil is facing both salinization and heavy metal pollution in china, exploring the role of cell wall in the mechanism that plant absorb heavy metals will provide the basis data for the safe use of contaminated soil. In this paper, the Cd Low accumulation variety(Bai gu xiao yuan ye you amaranth, hong liu ye amaranth) and high accumulation variety(hua hong amaranth, liu ye amaranth) grow with the method of hydroponic experiment under Na Cl concentration(CK, 0.2%, 0.3%, 0.4%) and 0.25μmol Cd combined stress. By measuring the content changing of six kinds of root cell wall components and seven kinds of nutrient elements including root cell wall and intracellular, exploring the influence of changing of root cell wall components and elements on the adsorption and uptake contents of Cd in root. The results showed that:Under salt stress, with the increase of salinity gradient, the comprehensive changes of the content of pectin, cellulose and total pectin methyl esterification degree lead to the adsorption contents of Cd in bai gu xiao yuan ye you amaranth root cell wall decreased firstly and then increased significantly, in 0.2% salinity minimum value. the comprehensive changes of the content of hemicellulose2 content and pectin Methylation degrees lead to the adsorption contents of Cd in hua hong amaranth root cell wall decreased firstly and then increased significantly, in 0.3% salinity minimum value. the comprehensive changes of the content of cellulose, hemicellulose1, hemicellulose2, protein lead to the adsorption contents of Cd in liu ye amaranth root cell wall significant rise overall. the comprehensive changes of the content of pectin, hemicellulose1, hemicellulose2 and pectin methylation degree lead to the adsorption contents of Cd in hong liu ye amaranth root cell wall significantly lower, at the same time have no significant change between salt stress. Overall, the adsorption contents of Cd in all varieties amaranth root cell wall is mainly affected by the changing of hemicellulose 2, cellulose content and pectin methylation degree, at the same time, the varietal differences in responses to salt stress lead to the varietal differences that the influence of changing of root cell wall components on the adsorption contents of Cd in root.Under salt stress, Through analysis of the relationship of content changing between the element and Cd in amaranths root cell wall and intracellular, infer the indirect influence way of the elements on the adsorption and uptake contents of Cd in root:under the same Cd treatment, with the increase of salinity, Na+ and Cd2+ have antagonistic effect on the cell wall binding sites, which influenced the Cd adsorption content in the cell wall; Ca2+ and Mn2+ can influent the content of polysaccharide and pectin, which influenced the Cd adsorption content in these constituent; Mg2+ in the intracellular can influent the content of polysaccharide and protein, which influenced the Cd adsorption content in these constituent; K+ and Fe2+/3+ combine to influent the content of polysaccharide, which influenced the Cd adsorption content in this constituent; Zn2+ and Cd2+ compete to the binding sites of hemicellulose1, cellulose and protein, which influenced the Cd adsorption content in these constituent. Over all, The Cd uptake content decreased is caused by the competition and comprehensive effect between ions,when the Na+、Ca2+、Mg2+、Zn2+and Cd2+ through the Ca channel.