| This study is based on a pot controlled trials,which test Hyperaccumulator ability of Youngia erythrocarpa in Cd for different contaminated soil (Cd concentration of 0 mg/ kg,25 mg/kg,50 mg/kg,75 mg/kg,100 mg/kg) condition, and suggests Youngia erythrocarpa’s Hyperaccumulation ability of Cd. Besides, the research on its physiological metabolism and antioxidant enzyme activity and Cd in the plant body cell morphology and chemical sub-distribution systems, the main results are as follows:(1)Youngia erythrocarpa’s Hyperaccumulation Ability:Under the condition of Cd concentrations in soil 25,50,75,100 mg/kg, the Cd content in upper portion of Youngia erythrocarpa was 121.90 mg/kg,178.93 mg/kg,261.36 mg/kg and 317.87 mg/kg, which all exceeding the Cd defined value of 100 mg/kg;In the meantime, at different concentrations, Youngia erythrocarpa’s enrichment factor and transfer coefficients are bigger than 1.0, and the enrichment factor at the root of 100 mg/kg treatment reach maximum 2.92, aboveground enrichment factor and transfer coefficient at 25 mg/kg treatment reach maxium 4.88 and 1.86,respectively, which are also up to standard Cd hyperaccumulation. From that, Youngia can be seen as a Cd hyperaccumulator.(2) Youngia erythrocarpa’s activity change of antioxidant defense enzymes:SOD, POD and CAT activity of aboveground processing are all greater than the underground part, and the SOD, CAT, POD activity are not phase consistency with increase of Cd concentration test, SOD increases first and then decreased in the 0-75 mg/kg, CAT presented as incremental, POD is reduced to a minimum when 1 OOmg/kg;(3) Changes in leaf chlorophyll:With the increase of Cd concentration, the film leaves chlorophyll a, chlorophyll b and total chlorophyll of Youngia erythrocarpa show a decreasing trend and a significant concentration effect, which indicates that photosynthesis of Youngia erythrocarpa has an inhibition effect on Cd, at the same time, total chlorophyll reach to maximum of12.8mg/g·FW under CK treatment;(4) The changes of Cd accumulation in different organs of Youngia erythrocarpa: Cd in Youngia erythrocarpa subcellular in root、stems and leaves shows that:the Cd distribution in root cells express soluble fraction> cell wall components> membranes and organelles; distribution of stem and leaf cells showed cell wall components> soluble fraction> membranes and organelles. According to that, retaining walls and vacuole isolation is the main way of Youngia erythrocarpa to accumulate Cd. Study manifests that: the main function of cytoderm in leaf cells is immobilization, and the main role of root cells is the vacuoles isolation.(5) The distrubition of Cd extraction in Youngia erythrocarpa shows that, Cd is mainly as sodium chloride extractable (FNaCl), water-extractable (Fw) and acetic acid extractable (FHac) comes second, which describe Cd is mainly as organic acid, pectin, phosphate and protein binding form in Youngia erythrocarpa, which exists in can effective in lightening injury of Cd to cell and plant body. |
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