THE SPECIATION OF CD IN CD HYPERACCUMULATING PLANT (SEDUM ALFREDII HANCE)

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 镉(Cd)是一种剧毒的土壤污染物，抑制植物的生长和产量，经常被重要的农业作物积累，对动物和人类健康有很大的潜在危害。然而，在中国，多达2000万公顷的土地受到了这种金属的污染。超积累Cd的植物对污染土壤的潜在植物修复具有重要意义。东南景天是中国特有的一种Cd超积累植物，对其超积累Cd的生理和分子机制的深入研究有助于其在植物修复中的潜在应用。其中，金属离子的形态是超积累植物金属超耐性的重要方面之一。一些配体(硫、氧/氮配位)参与了超积累植物对金属的解毒作用，表现为运输、络合、区隔和细胞修复。本工作是利用MicroSXRF和XAS对超积累菌Cd的细胞定位和形态的前沿性研究。XAS是一种元素特异性分析方法，因此特别适合于分析植物体内Cd的配基环境。本课题组对阿尔弗雷迪链霉菌对锌、镉的吸收、转运和积累的生理特性进行了大量的研究工作，并通过北京生物科学研究基金会、中国和日本KEK-PF的微型SXRF和XAS实验为解释锌在阿尔弗雷迪链霉菌中的定位和形态提供了实验证据。尽管如此，仍有必要利用微型SXRF和XAS在细胞水平上进一步了解Cd的形态，这在BSRF或KEK中是无法检测到的。因此，我们在SSRL站进行了这项实验，旨在解释Cd在Alfredii中的形态及其对SSRL中锌和Cd超积累的动态平衡机制。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Cadmium (Cd) is a highly toxic pollutant of soils, which inhibits plant growth and yield production, and is frequently accumulated by agriculturally important crops with a significant potential to impair animal and human health. However, in China, up to 20 million hectare has been polluted by this metal. Plants hyperaccumulating Cd are of considerable interest for potential phytoremediation of the contaminated soils. Sedum alfredii has been identified as a Cd hyperaccumulator native to China, and the better understanding of its physiological and molecular mechanisms in hyperaccumulating Cd may contribute to its potential use in phytoremediation. Here, the speciation of metal ions was one of the important aspects in metal hypertolerance of hyperaccumulators. Some ligands (sulfur, oxygen/nitrogen coordinated) was suggested to be involved in the detoxification of metals in the hyperaccumulating plants which exhibited as transport, chelation, compartmentation and cellular restoration. This work is a frontier research on cellular localization and speciation of Cd in the hyperaccumulator S. alfredii by using micro-SXRF and XAS. XAS is an element specific method and, therefore, particularly suited for analyzing the in vivo ligand environment of Cd in plants. Much work has been done by our research group on physiological characterization of uptake, translocation and accumulation of Zn and Cd in S. alfredii, and several experimental evidence has been obtained for the explanation of Zn localization and speciation in the S. alfredii by micro-SXRF and XAS experiments in BSRF, China, and KEK-PF, Japan. Still, it is necessary to further understand the speciation of Cd at cellular levels by using micro-SXRF and XAS, which is not detectable in BSRF or KEK. Thus, we apply for this experiment at SSRL station aiming at explaining the speciation of Cd in S. alfredii and its homeostatic mechanisms of Zn and Cd hyperaccumulation in S. alfredii.