title: Calcium Deficiency Triggers Phloem Remobilization of Cadmium in a Hyperaccumulating Species.
abstract: Understanding cadmium (Cd) accumulation in plants is critical for the development of plant-based strategies for soil remediation and crop safety. Sedum alfredii is a nonbrassica plant species known to hyperaccumulate Cd. The characteristics of Cd uptake, distribution, and retranslocation affected by the Ca status were investigated at cellular levels in S. alfredii Low Ca supply significantly increased Cd contents in shoots of S. alfredii, particularly in the young leaves. Micro x-ray fluorescence images confirmed that sequestration of Cd was greatly enhanced in the young leaves under Ca deficiency stress, with a significant amount of Cd localized in mesophyll cells, compared to the young leaves supplied with high Ca levels. Cd influx into protoplasts isolated from young leaves was significantly inhibited by the addition of Ca channel inhibitors, but not by pre-exposure to Ca deficiency. In stems, the Cd signal in vascular systems under low Ca levels was 10-fold higher than in those treated with higher Ca levels. A detailed investigation of vascular bundles revealed that an extremely high Cd signal induced by low Ca supply occurred in the phloem tissues, but not in the xylem tissues. Transfer of Cd pretreated plants to nutrient solutions at different Ca levels confirmed that a much higher amount of Cd was reallocated to the new growth tissues under low Ca stress compared to plants supplied with sufficient Ca. These results suggest that Ca deficiency triggered a highly efficient phloem remobilization of Cd in S. alfredii and subsequently enhanced Cd accumulation in its young leaves.
authors: Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Ministry of Education, Hangzhou 310058, China (S.T., R.X., H.W., Y.H., J.G, X.C.L., X.G., L.L.).|Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China (H.W., Y.H., X.G., X.Y.L., L.L.); and.|Department of Plant Sciences, University of California, Davis, California 95616 (P.B.).
authors: Shengke
authors: S
authors: Tian
authors: Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Ministry of Education, Hangzhou 310058, China (S.T., R.X., H.W., Y.H., J.G, X.C.L., X.G., L.L.).|Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China (H.W., Y.H., X.G., X.Y.L., L.L.); and.|Department of Plant Sciences, University of California, Davis, California 95616 (P.B.).
authors: Ruohan
authors: R
authors: Xie
authors: Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Ministry of Education, Hangzhou 310058, China (S.T., R.X., H.W., Y.H., J.G, X.C.L., X.G., L.L.).|Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China (H.W., Y.H., X.G., X.Y.L., L.L.); and.|Department of Plant Sciences, University of California, Davis, California 95616 (P.B.).
authors: Haixin
authors: H
authors: Wang
authors: Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Ministry of Education, Hangzhou 310058, China (S.T., R.X., H.W., Y.H., J.G, X.C.L., X.G., L.L.).|Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China (H.W., Y.H., X.G., X.Y.L., L.L.); and.|Department of Plant Sciences, University of California, Davis, California 95616 (P.B.).
authors: Yan
authors: Y
authors: Hu
authors: Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Ministry of Education, Hangzhou 310058, China (S.T., R.X., H.W., Y.H., J.G, X.C.L., X.G., L.L.).|Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China (H.W., Y.H., X.G., X.Y.L., L.L.); and.|Department of Plant Sciences, University of California, Davis, California 95616 (P.B.).
authors: Jun
authors: J
authors: Ge
authors: Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Ministry of Education, Hangzhou 310058, China (S.T., R.X., H.W., Y.H., J.G, X.C.L., X.G., L.L.).|Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China (H.W., Y.H., X.G., X.Y.L., L.L.); and.|Department of Plant Sciences, University of California, Davis, California 95616 (P.B.).
authors: Xingcheng
authors: X
authors: Liao
authors: Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Ministry of Education, Hangzhou 310058, China (S.T., R.X., H.W., Y.H., J.G, X.C.L., X.G., L.L.).|Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China (H.W., Y.H., X.G., X.Y.L., L.L.); and.|Department of Plant Sciences, University of California, Davis, California 95616 (P.B.).
authors: Xiaoyu
authors: X
authors: Gao
authors: Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Ministry of Education, Hangzhou 310058, China (S.T., R.X., H.W., Y.H., J.G, X.C.L., X.G., L.L.).|Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China (H.W., Y.H., X.G., X.Y.L., L.L.); and.|Department of Plant Sciences, University of California, Davis, California 95616 (P.B.).
authors: Patrick
authors: P
authors: Brown
authors: Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Ministry of Education, Hangzhou 310058, China (S.T., R.X., H.W., Y.H., J.G, X.C.L., X.G., L.L.).|Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China (H.W., Y.H., X.G., X.Y.L., L.L.); and.|Department of Plant Sciences, University of California, Davis, California 95616 (P.B.).
authors: Xianyong
authors: X
authors: Lin
authors: Key Laboratory of Environment Remediation and Ecological Health, College of Environmental and Resource Science, Zhejiang University, Ministry of Education, Hangzhou 310058, China (S.T., R.X., H.W., Y.H., J.G, X.C.L., X.G., L.L.); lulingli@zju.edu.cn.|Zhejiang Provincial Key Laboratory of Subtropic Soil and Plant Nutrition, Zhejiang University, Hangzhou 310058, China (H.W., Y.H., X.G., X.Y.L., L.L.); and lulingli@zju.edu.cn.|Department of Plant Sciences, University of California, Davis, California 95616 (P.B.) lulingli@zju.edu.cn.
authors: Lingli
authors: L
authors: Lu
mesh_terms: D002104:Cadmium / Q000378:metabolism*; D002118:Calcium / Q000172:deficiency*; D058503:Mesophyll Cells / Q000378:metabolism; D052585:Phloem / Q000378:metabolism*; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism; D018547:Plant Stems / Q000254:growth & development / Q000378:metabolism; D058526:Plant Vascular Bundle / Q000378:metabolism; D011523:Protoplasts / Q000378:metabolism; D031963:Sedum / Q000378:metabolism*; D013052:Spectrometry, X-Ray Emission
chemical_list: D002104:Cadmium; D002118:Calcium