| Heavy metals can go into the food chain by plant absorbing, and finally threatened human health seriously. Therefore the problems of heavy metal polluted soil get the attention of the people gradually. Phytoremediation has become research hot spot as a technique that greenly clean up heavy metal from polluted soil, easy to operate and cost effective. Ramie (Boehmeria nivea (L.) Gaud.), also named"China grass", belong to Urticaceae Boehmeria, is a perennial fiber crops. Ramie not only has anti-stress resistance ability, large root, rapid growth, but also has strong tolerance ability in varieties of heavy metals. Those make it to be the ideal plant to renovate heavy metals from contaminated soil.This paper mainly has worked on four aspects of researches.1) Rhizosphere soil was collected for detecting soil heavy metal pollution in mine area.2) Plant samples was collected for detecting heavy metal content in ramie.3) Using real-time fluorescent quantitative PCR,Real-time fluorescent quantitative PCR were carried out to study16cadmium stress response gene expression patterns in four varieties.4)Clone the full length cDNA sequence of glucose6phosphate dehydrogenase gene in XiangZhu3. The main results were as follows:1) Three mining areas are compound polluted by a variety of heavy metals,the content of cadmium, lead, manganese in Xiangtan manganese ore samples is4.08mg/kg-46.68mg/kg,170.04-5758.5mg/kg and7344.16-150802.6mg/kg, respectively.Then we can found our that cadmium content exceed the national standard level3in all sample and the lead content exceed over the national standard level3in80%sampling.The soil comprehensive pollution index is largest which range from13.71to249.51in T5sampling area. The content of cadmium, lead, zinc in Chenzhou ore samples is2.2mg/kg-1967mg/kg,147.68mg/kg-114780mg/kg, and175.24mg/kg-255180mg/kg, respectively. The cadmium content exceed the national standard level3in all sample. The lead content was higher than the national level3standard by over82%of the sample point and zinc content was higher than the national level3standard by over86%of the sample point and the biggest lead and zinc content were229.56multiples,510.36multiples higher than the national level3standard respectively.The soil comprehensive pollution index is largest that range from1.70to1516.32in B21sampling area. High resistance to heavy metal wild ramie may have been formed through long-term adaption to the soil in high concentration of heavy metal.2) Pb,Mn concentration in ramie leaves were higher than that in roots and stems in ramie grew in Xiangtan manganese ore, while other heavy metal concentration distribution in ramie tissue was disorder. Among these samples, the highest bioaccumulation factor and transfer factor of Pb were0.64and15.12. The highest bioaccumulation factor and transfer factor of Cd were4.72and13.15. The highest bioaccumulation factor and transfer factor of Mn were0.3and39.09. And the highest bioaccumulation factor and transfer factor of Zn were2.63and18.57. The total accumulations of Pb,Cd,Mn and Zn in these ramie samples were reached209.53,5.62,590.12and110.60mg/m2, respectively. Ramie is suitable for control and repair of the soil which polluted by heavy metal.3)16genes selected from expression spectrum sequencing using ramie root organs were carried on expression analysis in root,stem and leaf of four ramie varieties that tolerance and enrichment to cadmium. The results were as follows:1) The expression of Unigene17779, Unigene42350, Unigene8063, Unigene46921, Unigene27298was induced by cadmium stress, that means they were involved in ramie resistance to cadmium stress mechanism.Under cadmium stress can abate the expression of Unigene27228, that means this gene has nothing to do with the resistance to cadmium poisoning. Unigene17415is not related with the root resistance to cadmium stress mechanism. Under cadmium stress patterns of expression Unigene46654may be associated with root type.2) Unigene46238, Unigene48133involved in cadmium stress in specific material(Shi xian zhu gen ma).Unigene46677may indirectly involved in resistance to cadmium stress and transport of cadmium accumulation.3)The expression of Unigene47454, Unigene48199are not induced by cadmium stress.4)The expression of Unigene48537is not induced by cadmium stress.5)The expression of Unigene44271is not induced by cadmium stress.6)Unigene26576involved in response to cadmium stress and they receive the feedback regulation of GST content. There were big difference in the gene expression patterns in different ramie varieties, it may be associated with genotype.4) The full-length cDNA sequence of BnG6PDH were cloned. The full-length and the ORF of BnG6PDH were1733bp and1554bp, which encoded517amino acids with predicted molecule weight and pI were34.466KD and7.779. G6PDH conservative functional domains were found in this gene.The results of subcellular localization analysis showed that the BnG6PDH which has no signal peptide and the membrane structure domain located in cytoplasm.Evolutionary tree analysis showed that BnG6PDH gene and G6PDH gene of other species share high conservative of amino acids sequence. The G6PDH of soybean and clover have closer genetic relationship to BnG6PDH than that of sweet orange, poplar, coco tree, Actinidia chinensis, strawberry. Then the G6PDH of cucumber and Arabidopsis thaliana have less genetic relationship than that of sweet orange, poplar, coco tree, Actinidia chinensis and strawberry. |
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