title: Expression of cadR Enhances its Specific Activity for Cd Detoxification and Accumulation in Arabidopsis.
abstract: Cadmium (Cd) is a transition metal that is highly toxic in biological systems. Anthropogenic emissions of Cd have increased biogeochemical cycling and the amount of Cd in the biosphere. Here we studied the utility of a bacterial Cd-binding protein, CadR, for the remediation of Cd contamination. CadR was successfully targeted to chloroplasts using a constitutive Cauliflower mosaic virus (CaMV) 35S promoter or a shoot-specific Chl a/b-binding protein 2 gene (CAB2) promoter and an RbcS (small subunit of the Rubisco complex) transit peptide. Under short-term (2 d) exposure to Cd, the cadR transgenic plants showed up to a 2.9-fold Cd accumulation in roots compared with untransformed plants. Under medium term (7 d) exposure to Cd, the concentrations of Cd in leaves began to increase but there were no differences between the wild type and the cadR transgenic plants. Under long-term (16 d) exposure to Cd, the cadR transgenic plants accumulated greater amounts of Cd in leaves than the untransformed plants. Total Cd accumulation (µg per plant) in shoots and roots of the plants expressing cadR were significantly higher (up to 3.5-fold in shoots and 5.2-fold in roots) than those of the untransformed plants. We also found that targeting CadR to chloroplasts facilitated chloroplastic metal homeostasis and Chl b accumulation. Our results demonstrate that manipulating chelating capacity in chloroplasts or in the cytoplasm may be effective in modifying both the accumulation of and resistance to Cd.
authors.affiliation: Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China College of Life Science, Shanxi Normal University, Shanxi Linfen 041004, China These authors contributed equally to this work.
authors.forename: Jingrui
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Life Science, Shanxi Normal University, Shanxi Linfen 041004, China These authors contributed equally to this work.
authors.forename: Xuezhi
authors.initials: X
authors.lastname: Wei
authors.affiliation: Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Pengli
authors.initials: P
authors.lastname: Yu
authors.affiliation: Department of Chemistry and Institute for Biophysical Dynamics, the University of Chicago, Chicago, IL 60637, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Deng
authors.affiliation: Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Wenxiu
authors.initials: W
authors.lastname: Xu
authors.affiliation: Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Mi
authors.initials: M
authors.lastname: Ma
authors.affiliation: Key Laboratory of Plant Resources, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China hyz@ibcas.ac.cn.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Zhang
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001673:Biodegradation, Environmental; D002104:Cadmium / Q000378:metabolism* / Q000633:toxicity; D017796:Caulimovirus / Q000235:genetics; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D015870:Gene Expression; D017930:Genes, Reporter; D006706:Homeostasis; D008658:Inactivation, Metabolic; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism*; D008903:Minerals / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D018520:Plant Shoots / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D036226:Seedlings / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D019076:Transgenes
chemical_list: D001426:Bacterial Proteins; D008903:Minerals; C004203:cadmium-binding protein; D002104:Cadmium; D002734:Chlorophyll; D008668:Metallothionein
keywords: Arabidopsis; CadR; Cadmium (Cd); Chloroplast targeting; Fe; Mn