镉胁迫下白杨抗坏血酸及谷胱甘肽循环代谢.docVIP

PAGE 陕西理工学院毕业论文（设计） 毕业论文（设计） 题 目 镉胁迫下白杨抗坏血酸和谷胱甘肽循环代谢的 研究 学生姓名 学号 所在院(系) 生物科学与工程学院 专业班级 指导教师 2015年5月25日 镉胁迫下白杨抗坏血酸和谷胱甘肽循环代谢的研究 （陕西理工学院 生物科学与工程学院，陕西 汉中 723000） 指导教师： [摘要] 本研究以白杨组培苗为材料，采用土培方法，研究了白杨在Cd2+胁迫下，不同器官中丙二醛（MDA）、过氧化氢（H2O2）含量显著增加，导致膜脂过氧化加剧。白杨能够通过增强超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）活性，增加总抗坏血酸(AsA)、抗坏血酸(AsA)、抗坏血酸/脱氢抗坏血酸(AsA/DHA)含量来减少膜脂过氧化伤害。但高浓度、较长时间的Cd2+胁迫也会造成CAT、SOD、APX酶受损，酶活性降低，导致脱氢抗坏血酸（DHA）、还原型谷胱苷肽(GSH)、还原型谷胱苷肽/氧化型谷胱苷肽(GSH/GSSG)与总谷胱苷肽(GSH+GSSG)含量下降。进一步表明白杨对Cd2+的耐受性及其解毒机理，以期为其在植物修复技术改良与优化中的应用提供科学依据。 [关键词] 镉；白杨；抗坏血酸；谷胱甘肽； Metabolism of ascorbate and glutathione cycle in white poplar under Cd2+ stress (Shaanxi Institute of, Hanzhong, Shaanxi 723000) Tutor: [Abstract] In this study, white poplar was used as the experimental material and soil experiment was conducted under four Cd2+ concentrations (10, 30, 50, and 70 μM·L-1) for 7, 14, 21 and 28 d by using non-Cd as the control, in order to investigate the effects of Cd2+ on poplar photosynthesis, antioxidantive ability and the relation between Cd2+ chelation and ability of Cd2+ tolerance in plant.The result showed that the contents of MDA and H2O2 among different tissues in white poplar significantly increased, which indiated that the lipid peroxidation was aggravated.White poplar could reduce the lipid peroxidation by increasing the activities of SOD, CAT, and APX and total AsA, AsA, AsA/DHA contents. While, under high concentration Cd2+ stress, the activities of CAT, SOD, APX and the contents of DHA, GSH, GSH/GSSG, GSH+GSSG both decreased gradually. GSH and AsA contents in white poplar was decreased with the increased of Cd2+ concentration, this results indicated an crucial role played by GSH and AsA in Cd2+ tolerance and detoxification in white poplar.Thus, our study is dedicated to elucidate the mechanism of Cd2+accumula