title: Cadmium and manganese accumulation in Phytolacca americana L. and the roles of non-protein thiols and organic acids.
abstract: Phytolacca americana L. can accumulate large amounts of heavy metals in its aerial tissues, especially cadmium (Cd) and manganese (Mn). It has great potential for use in phytoextraction of metals from multi-metal-contaminated soils. This study was conducted to further investigate the Cd- and Mn-tolerance strategies of this plant. Concentrations of non-protein thiols (NPTs) and phytochelatins (PCs) in leaves and roots increased significantly as the concentration of Cd in solution increased. The molar ratios of PCs:soluble Cd ranged from 1.8 to 3.6 in roots and 8.1 to 31.6 in leaves, suggesting that the cellular response involving PC synthesis was sufficient to complex Cd ions in the cytosol, especially that of leaves. In contrast, excess Mn treatments did not result in a significant increase in NPT or PC concentrations in leaves or roots. Oxalic acid concentrations in leaves of plants exposed to 2 or 20 mM Mn reached 69.4 to 89.3 mg (0.771 to 0.992 mmol) g(-1) dry weight, respectively, which was approximately 3.7- to 8.6-fold higher than the Mn level in the 0.6 M HCl extract. Thus, oxalic acid may play an important role in the detoxification of Mn.
authors.affiliation: College of Life Sciences, Nanjing Agricultural University, Nanjing, the People's Republic of China.
authors.forename: Lu
authors.initials: L
authors.lastname: Gao
authors.forename: Kejian
authors.initials: K
authors.lastname: Peng
authors.forename: Yan
authors.initials: Y
authors.lastname: Xia
authors.forename: Guiping
authors.initials: G
authors.lastname: Wang
authors.forename: Liyuan
authors.initials: L
authors.lastname: Niu
authors.forename: Chunlan
authors.initials: C
authors.lastname: Lian
authors.forename: Zhenguo
authors.initials: Z
authors.lastname: Shen
mesh_terms: D001673:Biodegradation, Environmental; D002104:Cadmium / Q000378:metabolism* / Q000494:pharmacology; D002264:Carboxylic Acids / Q000032:analysis / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D018527:Hydroponics; D015227:Lipid Peroxidation; D008345:Manganese / Q000378:metabolism* / Q000494:pharmacology; D009928:Organ Specificity; D019815:Oxalic Acid / Q000032:analysis / Q000378:metabolism; D054811:Phytochelatins / Q000378:metabolism*; D029604:Phytolacca americana / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D018515:Plant Leaves / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D012989:Soil Pollutants; D013312:Stress, Physiological; D013438:Sulfhydryl Compounds / Q000032:analysis / Q000378:metabolism*
chemical_list: D002264:Carboxylic Acids; D012989:Soil Pollutants; D013438:Sulfhydryl Compounds; D002104:Cadmium; D008345:Manganese; D054811:Phytochelatins; D019815:Oxalic Acid