超积累植物伴矿景天对镉和铅动态吸收与转运的非损伤微测研究

Information on the rate of uptake and transport of metals within the plants is essential to better understand the physiology of metal accumulation in the hyperaccumulators. Traditional destructive technologies with poor spatial and temporal resolution have limited capabilities in analyzing root samples and sometimes may result in false conclusion. The Non-invasive Micro-test Technology (NMT) enable us to real-time get the information on flux rate of ions or molecules into or out of the samples without any damages under the real physiological condition. In this study, the kinetics uptake and transport of Cd2+ and Pb2+ in the hyperaccumulator hyperaccmulating ecotype Sedum plumbizincicola, in comparison with its non-hyperaccumulating ecotype, were investigated non-invasively by combination of several in situ techniques including NMT, synchrotron radiation and fluorescent probe , under hydroponic culture condition. The objectives of this study are: 1) to reveal ion flux characteristic in the Cd2+ and Pb2+ uptake and transport kinetics of Sedum plumbizincicola; 2) to determine the effect of co-existing cations, low molecular weight organic acids and plant growth promoting rhizobacteria on the Cd2+ and Pb2+ uptake and transport kinetics of Sedum plumbizincicola; 3) to clarify the relationship between Cd2+ and Pb2+ uptake and transport kinetics and their element distribution and species in different organs of plant. The results from this project will improve our understanding of the hyperaccmulating mechanism of Sedum plumbizincicola and is crucial for developing more efficient phytoremediation technologies to clean up metal-contaminated soil using hyperaccumulator Sedum plumbizincicola.

探明超积累植物对重金属的吸收与转运过程和机制，有助于了解其超积累的生理机理。传统方法由于对样品的破坏性常造成测试结果无法合理解释甚至导致研究假象，非损伤微测能在保持被测样品完整和近乎实际的生理状态下实时、连续获取进出活体组织离子或分子的运动信息。本研究以超积累和非超积累生态型伴矿景天为材料，采用水培方法，综合运用非损伤微测、同步辐射以及荧光探针显微等活体、原位技术，利用自主研发的重金属离子选择性微电极，揭示活体条件下伴矿景天动态吸收、转运Cd2+ 和Pb2+的离子流特征；明确共存阳离子、低分子量有机酸以及根际促生菌对伴矿景天动态吸收、转运Cd2+ 和Pb2+的影响及控制机制；探明伴矿景天对Cd2+ 和Pb2+动态吸收、转运与其体内不同器官静态分布和赋存形态的关系。研究结果为全面理解和认识伴矿景天对重金属的超积累生理生化机理，提高Cd/Pb污染土壤的伴矿景天植物修复效率提供科学理论依据。

探明超积累植物对重金属的吸收与转运过程和机制，有助于了解其超积累的生理机理。传统方法由于对样品的破坏性常造成测试结果无法合理解释甚至导致研究假象，非损伤微测能在保持被测样品完整和近乎实际的生理状态下实时、连续获取进出活体组织离子或分子的运动信息。本项目在前期工作的基础上，率先研发了基于非损伤微测技术的重金属离子流活体检测技术，实现了根际微区铅、铜、锌等重金属离子流的实时、动态、无损检测。研发的重金属（Pb2+,Cu2+,Zn2+）离子流微传感器填补了国内外市场空白，已授权国家发明专利2项，公开国家发明专利1项。该产品目前已通过旭月（北京）科技有限公司提供对外重金属离子流检测服务和销售，具有广阔应用前景。进一步运用研发的离子流检测技术揭示了活体条件下不同生态型超积累植物伴矿景天动态吸收与转运Cd2+和Pb2+的离子流特征；借助代谢抑制剂及离子通道抑制剂，分别从静态积累和动态吸收角度阐明伴矿景天对Cd2+的吸收主要是一个主动吸收过程，且受H+浓度梯度的驱动完成。伴矿景天可借助质膜Ca2+和K+通道来完成对Cd2+的吸收转运。植物络合素在伴矿景天吸收转运Cd2+的过程中也起到一定作用。除离子通道外，伴矿景天还可能借助专一性转运蛋白来吸收Cd2+,这需进一步通过分子生物学等手段进行验证。研究还通过比较离子流速发现了一株能促进伴矿景天Cd吸收的促生菌。本项目研究结果为根际重金属离子流速的实时、动态、活体检测提供了方法学参考和借鉴，也为全面理解和认识伴矿景天对重金属的超积累生理生化机理，提高Cd/Pb污染土壤的伴矿景天植物修复效率提供科学理论依据。