Development of Enhanced Plants for Remediation of Cadmium and Lead

描述（由申请人提供）：重金属镉和铅都是严重的环境污染物，根据其毒性和在环境中的普遍性，被有毒物质和疾病登记署（美国卫生与公众服务部）列为十大危害之一。例如，铅污染是普遍的，因为直到1978年铅基涂料的普遍使用。即使在最近，美国环保局估计，1,200万家庭的院子里的铅含量超过了游戏区400 ppm的新标准，而470万家庭的院子里的铅含量超过了1,200 ppm的新标准。传统的补救方法，挖掘和清除污染土壤，对于如此大的面积是不可行的，但植物补救，或使用植物吸收污染物，可以提供一种替代的，具有成本效益的方法。 虽然已经确定植物可以耐受其环境中高水平的有毒金属，但其中许多植物不适合基于它们产生的低量生物质或其有限的生长范围进行植物修复。为了提高铅和镉等金属的植物修复潜力，加州大学圣地亚哥分校朱利安·施罗德博士的实验室已经确定了两个候选基因，这些基因已被证明可以增加植物中金属的耐受性和积累。第一个基因，3-ECS编码谷胱甘肽合成的关键酶，谷胱甘肽是金属耐受性和氧化应激反应的重要组成部分。第二个基因YCF 1编码ABC转运蛋白，将谷胱甘肽金属复合物转运到液泡中，将金属隔离在那里并降低金属的细胞毒性。这两个基因将在一株植物中叠加在一起，以测试它们将协同作用并提供显着增加的耐受性的假设。转基因植物用于植物修复的潜力将通过从受污染场地收集的土壤来证明，然后在第二阶段在其中一个场地进行实地试验。镉和铅等有毒金属一直被美国环境保护署和美国卫生与公众服务部列为最大的环境危害之一，但传统的修复方法过于昂贵，无法解决广泛的污染问题。该SBIR项目将开发增强植物，可以积累比自然植物更高水平的镉和铅，从而从受污染的土壤或水中去除金属。这些植物可能会导致新的补救技术，与传统的解决方案相比，减少对环境的影响。

DESCRIPTION (provided by applicant): The heavy metals cadmium and lead are both serious environmental contaminants that are listed among the top ten hazards by the Agency for Toxic Substances and Disease Registry (U.S. Department of Health and Human Services) based on their toxicity and prevalence in the environment. For example, lead contamination is widespread due to the ubiquitious use of lead based paints until 1978. Even recently, the USEPA estimated that 12 million homes have lead in their yards at levels exceeding the new 400 ppm standard for play areas, while 4.7 million homes exceed the new 1,200 ppm standard for the rest of the yard. Traditional means of remediation, excavation and removal of the contaminated soils, is not feasible for such a large area, but phytoremediation, or the use of plants to take up contaminants, can provide an alternative, cost-effective, method. While plants have been identified that can tolerate high levels of toxic metals in their environment, many of these plants are unsuitable for phytoremediation based on the low amounts of biomass they produce or their limited growing range. To improve the potential for phytoremediation of metals such as lead and cadmium, the laboratory of Dr. Julian Schroeder at the University of California, San Diego, has identified two candidate genes that have been demonstrated to increase metal tolerance and accumulation in plants. The first gene, 3-ECS encodes the key enzyme in the synthesis of glutathione, an essential component in metal tolerance and the oxidative stress response. The second gene, YCF1, encodes an ABC transporter that transports glutathione metal complexes into the vacuole, sequestering the metals there and reducing cellular toxicity of the metals. These two genes will be stacked together in a single plant to test the hypothesis that they will act synergistically together and provide significantly increased tolerance. The potential of the transgenic plant for phytoremediation will be demonstrated with soil collected from contaminated sites, followed in Phase II with a field trial at one of these sites. Toxic metals such as cadmium and lead are consistently classified as among the top environmental hazards by the Environmental Protection Agency and U.S. Department of Health and Human Services, but traditional remediation methods are too expensive to address the widespread contamination. This SBIR project will develop enhanced plants that can accumulate greater levels of cadmium and lead than naturally occurring plants, allowing for removal of the metals from contaminated soil or water. These plants could lead to novel remediation technologies with reduced environmental impact than traditional solutions.