【作者】 黄长干；

【导师】 邱业先；

【作者基本信息】 湖南农业大学 ， 植物学， 2007， 博士

【摘要】 本论文以我们在中国最大的铜矿——江西省德兴铜矿矿区筛选并报道的超积累Cu植物紫鸭跖草（Setcreasea purpurea Boom.）为试验材料,综合运用溶液培养法、相关酶分析方法、ICP-AES元素测定技术、差速和超速离心技术以及分子生物学研究技术等从几个不同方面研究了该植物对Cu的超积累机理,取得了如下的结果。紫鸭跖草（Setcreasea purpurea Boom.）能够超积累Cu,在1000μmol·L^-+ Cu供应水平时,紫鸭跖草地上部和地下部铜浓度分别高达1105和1210mg.kg^-1干重。紫鸭跖草对铜的吸收和转运效率依赖于培养液中的铜供应浓度,250μmol·L^-1以上Cu处理使Cu的转运效率急剧上升。在不同浓度Cu供应时,紫鸭跖草对其必需养分元素的吸收和积累维持正常,它们的浓度均在保证一般植物正常生长的浓度范围内。100μmol·L^-1～250μmol·L^-1 Cu的供应能明显促进植物生长。高浓度Cu对根和茎叶部分的蛋白质的含量、合成及氨基酸的组成有显著的影响。运用差速离心技术研究了Cu在紫鸭跖草亚细胞内的分配特征,结果表明,细胞壁是Cu分布的主要位点之一,其次,叶绿体中的Cu占叶片全Cu的较大比例。在接触高Cu或接触时间延长情况下,根细胞中Cu向细胞壁的分配增加,而向叶绿体中的分配减少,而叶细胞中Cu向叶绿体中的分配增多,向细胞壁的分配减少。运用化学试剂顺序提取法和酶解法研究了Cu在紫鸭跖草的根和叶片中的赋存形态,结果显示,叶片中Cu主要与氨基酸和小分子色素、蛋白质、多糖等结合,而根中Cu则主要与纤维素、膜结合蛋白等细胞壁物质相结合。根组织中细胞壁结合态Cu有60%左右与纤维素和/或果胶等相结合,能够被纤维素酶或离析酶所溶解。通过研究紫鸭跖草叶中抗氧化体系主要参数在不同浓度Cu影响下的变化发现,活性氧和自由基清除体系的APX、GPX、CAT和SOD活性根部始终高于叶部。在高于250μmol·L^-1 Cu处理时APX、GPX和SOD活性各抗氧化酶活性均显著升高,在低于250μmol·L^-1 Cu处理时表现各异。只有CAT活性却一直随Cu浓度的增大而下降。根部和叶部GR活性在100和250μmol·L^-1 Cu处理时显著高于其它Cu供应水平,GSH含量在250μmol·L^-1 Cu处理时较高;根中脯氨酸含量与Cu供应水平成线性相关,叶中脯氨酸含量与Cu供应水平成线性负相关。质膜透性和膜脂过氧化研究也表明紫鸭跖草在低于50或高于250μmol·L^-1 Cu供应时分别受到Cu缺乏或中毒胁迫。光合速率和蒸腾速率的试验结果以及根系活性研究结果均表明紫鸭跖草在较高浓度Cu供应时生长良好。以上研究结果表明紫鸭跖草对Cu有很大耐性和富集能力,又由于该植物的生物量较大、生长速率高,因此它在铜污染土壤的植物修复中有很大的应用潜力。更多还原

【Abstract】 Setcreasea purpurea Boom.,a Cu-tolerant and Cu-hyperaccumulating ecotype, was found in Dexing copper mining area in Jiangxi Province which is the biggest copper mine in china.Our studies were focus on the Cu-hyperaccumulating mechanism of Setcreasea purpurea Boom.by hydroponic approach,related enzyme analysis,ICP-AES element determination,differential centrifugation and ultarcentrifugation and molecular biology technology.The main results obtained were summarized as follows:Setcreasea purpurea Boom.has the ability to hyperaccumulate Cu.When the supply of Cu was 1000μmol·L^-1,the Cu concentration in shoots and roots was up to 1105 and 1210 mg·kg^-1DW,respectively.Copper uptake and translocating efficiency of Setcreasea purpurea Boom.depended on the Cu concentration in nutrient solution. and remarkably increased when Cu was over 250μmol·L^-1.At different Cu concentration,the uptake and accumulating of Setcreasea purpurea Boom.for necessary nutrient elements kept normal and the concentration of necessary nutrient elements made normal plant species grow.The Cu concentration from 100μmol·L^-1 to 250μmol·L^-1 obviously promoted the plant growth.High copper concentration has significant influence on the content of protein and component of amino acid in root and shoot.By means of differential centrifugation,the studies on copper distributing character in subcell of Setcreasea purpurea Boom.showed that Cu content mainly distributed in cell wall and Cu content in chloroplast was a majority of whole leaf Cu content.When Setcreasea purpurea Boom.was in the hydroponic solution with high Cu concentration or lengthen culture time,Cu in the root cell distributed more to cell wall and less to chloroplast,but the reverse was in the leaf cell.Cu occurrence characteristic in root and leaf researched by chemical agent order extraction and enzymatic hydrolysis.The results indicated that Cu in leaf mostly combined with amino acid,small molecular pigment,protein,amylose,etc and Cu in root mainly combined with cellulose,membrane banding protein in cell wall.About 60%of banding-Cu combined with cellulose and/or pectin could be dissolved by cellulase and dissociation enzyme.Main parameter of antioxidation system under different Cu levels supplied in nutrient solution were determined and analized.The activities of active oxygen and APX,GPX,CAT and SOD of free radical in root were higher than that in leaf.The activities of APX,GPX,SOD and antioxidation enzymes increased obviously When Cu concentration was over 250μmol,but differed when under 250μmol·L^-1.However, CAT activity was decreased with the increase of Cu concentration.GR activities in root and leaf at the supply of 100 and 250μmol·L^-1 Cu were remarkably higher than that at other Cu level,and GSH content was comparatively high at the supply of 250μmol·L^-1 Cu;proline content in root was correlated linearly to the Cu supplied level and in leaf was negative correlated linearly to the Cu supplied level.Plasma membrane permeability and membrane lipid peroxidation were researched,suggesting that Setcreasea purpurea Boom.was at the shortage of Cu when Cu supply below 50μmol·L^-1 and on copper toxic stress when Cu supply over 250μmol·L^-1. Photosynthesis and transpiration rate experiments and root system activity research indicated that Setcreasea purpurea Boom.grew well at the high Cu level.Due to its fast growth rate and high Cu-accumulating ability,from a phytoremediation perspective,accumulating ecotype of Setcreasea purpurea Boom.is a potential plant species for Cu removal from contaminated soils.更多还原