Project 7: Molecular Mechanisms of Heavy Metal Detoxification and Accumulation

总结（参见说明）： 土壤和沃茨中有毒重金属（loid）如砷、镉和汞含量高，对人类和环境健康有害。这三种金属（铅）是超级基金的前7名优先危险物质。研究和应用表明，植物通过根系吸收重金属并在地上部积累重金属，可以为重金属污染土壤和沃茨的去除和修复提供一种经济有效的途径。然而，在植物重金属过量积累中起重要作用的基因和途径仍有待确定。在最近的研究中，我们在理解重金属作用的关键机制方面取得了重大进展。 解毒、运输和植物中的积累。我们将结合联合收割机强大的基因组学，遗传学，生物化学和生理学方法，通过追求以下具体目标来测试新的中心假设： 表征新鉴定的液泡膜转运蛋白，其功能是将植物螯合素-重金属（类）复合物吸收和积累到植物液泡中，并分析其生物修复潜力。 了解重金属在根和地上部的积累和分布的控制对于植物生物修复工程至关重要。确定一个新的肽转运蛋白突变体，opt 3，导致镉在根中的超积累和在植物叶片中的积累不足的机制。 我们最近的研究表明，重金属螯合和解毒硫醇在植物中进行长距离运输。然而，用于摄取谷胱甘肽（GSH）和植物螯合素（PC）的质膜转运蛋白仍然未知。使用高通量筛选，我们现在已经确定OPT 4为推定的GSH & PC-Cd转运蛋白。我们将描述0 PT 4和其他转运蛋白，以确定其潜在的GSH/PC-Cd/As的运输机制和重金属在植物中的分布功能。 四.重金属诱导植物基因快速表达的机制和转录因子尚不清楚，但对植物的重金属抗性和积累具有重要意义。新分离的突变体镉诱导的基因表达受损的基因将被确定和其功能的特点。此外，一个有效的全基因组的方法已经开发出来，并将追求识别和表征关键的转录因子和抑制剂，控制镉和砷诱导的基因表达。我们将与RTC和CEC密切合作，分享我们的进展，最重要的是对我们的研究结果进行转化分析，以了解其在污染土壤和沃茨植物修复中的潜力。

SUMMARY (See instructions): Soils and waters with high levels of toxic heavy metal(loid)s such as arsenic, cadmium and mercury are detrimental to human and environmental health. These three metal(loid)s are among the Superfund's top 7 priority hazardous substances. Research and applications indicate that uptake of heavy metals into plants via the root system and accumulation of heavy metals in plant shoots could provide a cost effective approach for toxic metal removal and remediation of heavy metal-laden soils and waters. However important genes and pathways that function in heavy metal over-accumulation in plants remain to be identified. In recent research we have made major advances at understanding key mechanisms that function in heavy metal detoxification, transport and accumulation in plants. We will combine powerful genomic, genetic, biochemical and physiological approaches to test new central hypotheses by pursuing the following Specific Aims: L Characterize newly identified vacuolar membrane transporters that function in uptake and accumulation of phytochelatin-heavy metal(loid) complexes into plant vacuoles and analyze their bioremediation potential. \ l Understanding the control of heavy metal accumulation and distribution in roots and shoots is critical for engineering of plants for bioremediation. Determine the mechanisms by which a new peptide transporter mutant, opt3, causes hyper-accumulation in roots and under-accumulation of cadmium in plant leaves. iii Our recent research has shown that heavy metal-chelating and detoxifying thiols undergo long distance transport in plants. However, the plasma membrane transporters for uptake of glutathione (GSH) and phytochelatins (PCs) remain unknown. Using a high-throughput screen we have now identified OPT4 as a putative GSH & PC-Cd transporter. We will characterize 0PT4 and additional transporters to determine their underlying GSH/PC-Cd/As transport mechanisms and their functions in heavy metal distribution in plants. IV. The mechanisms and transcription factors that mediate rapid heavy metal-induced gene expression in plants remain largely unknown, but are important for heavy metal resistance and accumulation. The genes of newly isolated mutants impaired in cadmium-induced gene expression will be identified and their functions characterized. Furthermore, a potent genome-wide approach has been developed and will be pursued to identify and characterize key transcription factors and repressors that control cadmium- and arsenic-induced gene expression. We will work closely with the RTC and CEC in sharing our advances and foremost in translational analyses of our findings for their potential in phytoremediafion of contaminated soils and waters.