期刊
JOURNAL OF PLANT PHYSIOLOGY
卷 167, 期 12, 页码 981-988出版社
ELSEVIER GMBH, URBAN & FISCHER VERLAG
DOI: 10.1016/j.jplph.2010.02.010
关键词
AtPCS1; Cadmium; CePCS; Phytochelatins; Tobacco; Vacuoles
资金
- EU [FOOD-CT-2006-016253]
- Polish Ministry of Science and Higher Education [N N303 401036]
Exposure to Cd2+ leads to activation of phytochelatin synthase (PCS) and the formation of phytochelatins (PCs) in the cytosol. Binding of Cd by PCs and the subsequent transport of PC-Cd complexes to the vacuole are essential for Cd tolerance. Attempts to improve Cd detoxification by PCS overexpression have resulted in contrasting plant phenotypes, ranging from enhanced Cd tolerance to Cd hypersensitivity. In the present paper, changes in the subcellular phytochelatin, glutathione, gamma-glutamylcysteine and cadmium vacuolar and cytosolic distribution underlying these phenotypes were examined. Cadmium and PCs levels were determined in protoplasts and vacuoles isolated from leaves of Nicotiana tabacum expressing either of two phytochelatin synthase genes, AtPCS1 and CePCS (differing in their level of Cd tolerance: being Cd hypersensitive or more Cd-tolerant as compared to wild-type plants, respectively). We showed that Cd hypersensitivity of AtPCS1-expressing tobacco results from a significant decrease in both the cytosolic and vacuolar pool of PCs, indicating a decreased cadmium detoxification capacity. By contrast, enhanced Cd tolerance of CePCS plants was accompanied by an increased cytosolic and vacuolar SH of PC/Cd ratio, suggesting more efficient Cd detoxification. Surprisingly, the substantially reduced level of PCs did not influence Cd accumulation in vacuoles of AtPCS1-transformed tobacco (relative to the wildtype), which suggests the important role of mechanisms other than PC-Cd transport in Cd translocation to the vacuole. Our data suggest that the key role of the PCs in Cd tolerance is temporary binding of Cd2+ in the cytosol, and contrary to the current view, their contribution to cadmium sequestration seems to be less important. (C) 2010 Elsevier GmbH. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据