title: Subcellular cadmium distribution and antioxidant enzymatic activities in the leaves of two castor (Ricinus communis L.) cultivars exhibit differences in Cd accumulation.
abstract: The aims of this study were: (1) the study of cadmium (Cd) accumulation and toxicity in different castor cultivars (Ricinus communis L.); (2) to investigate changes in antioxidant enzymatic activities and the subcellular distribution of Cd in young and old leaves from two different castor cultivars, after exposure to two different Cd concentrations, and explore the underlying mechanism of Cd detoxification focusing on antioxidant enzymes and subcellular compartmentalization. The Cd concentration, toxicity, and subcellular distribution, as well as superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities were measured in Zibo-3 and Zibo-9 cultivars after exposure to two different concentrations of Cd (2mg/L and 5mg/L) for 10 days. This research revealed Cd accumulation characteristics in castor are root>stem>young leaf>old leaf. Castor tolerance was Cd dose exposure and the cultivars themselves dependent. Investigation of subcellular Cd partitioning showed that Cd accumulated mainly in the heat stable protein (HSP) and cellular debris fractions, followed by the Cd rich granule (MRG), heat denatured protein (HDP), and organelle fractions. With increasing Cd concentration in nutrient solution, the decreased detoxified fractions (BDM) and the increased Cd-sensitive fractions (MSF) in young leaves may indicate the increased Cd toxicity in castor cultivars. The BDM-Cd fractions or MSF-Cd in old leaves may be linked with Cd tolerance of different cultivars of castor. The antioxidant enzymes that govern Cd detoxification were not found to be active in leaves. Taken together, these results indicate Cd tolerance and toxicity in castor can be explained by subcellular partitioning.
authors.affiliation: Shenyang Academy of Environmental Science, Shenyang 110016, China; Center for Environmental Remediation, Institute of Geographical Sciences and Natural Resources, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: zhanghanzhihan@163.com.
authors.forename: Hanzhi
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Center for Environmental Remediation, Institute of Geographical Sciences and Natural Resources, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: guoqj@igsnrr.ac.cn.
authors.forename: Qingjun
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Center for Environmental Remediation, Institute of Geographical Sciences and Natural Resources, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Junxing
authors.initials: J
authors.lastname: Yang
authors.affiliation: University of Technology, Sydney, NSW 2007, Australia.
authors.forename: Jianxiu
authors.initials: J
authors.lastname: Shen
authors.affiliation: Center for Environmental Remediation, Institute of Geographical Sciences and Natural Resources, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Tongbin
authors.initials: T
authors.lastname: Chen
authors.affiliation: The State Key Laboratory of Environmental Geochemistry, Institute Of Geochemistry, Chinese Academy of Sciences, Guizhou 550002, China.
authors.forename: Guangxu
authors.initials: G
authors.lastname: Zhu
authors.affiliation: Shenyang Academy of Environmental Science, Shenyang 110016, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
authors.affiliation: Shenyang Academy of Environmental Science, Shenyang 110016, China.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Shao
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002104:Cadmium / Q000378:metabolism*; D002367:Ricinus communis / Q000201:enzymology*; D002374:Catalase / Q000378:metabolism; D008658:Inactivation, Metabolic; D009195:Peroxidase / Q000378:metabolism; D018515:Plant Leaves / Q000201:enzymology*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000201:enzymology; D018547:Plant Stems / Q000201:enzymology; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D010940:Plant Proteins; D002104:Cadmium; D002374:Catalase; D009195:Peroxidase; D013482:Superoxide Dismutase
keywords: Antioxidant enzyme; Cadmium; Castor; Detoxification mechanism; Subcellular distribution