title: Subcellular distribution and toxicity of cadmium in Potamogeton crispus L.
abstract: The submerged macrophyte Potamogeton crispus L. was subjected to varying doses of cadmium (0, 20, 40, 60 and 80 μM) for 7 d, and the plants were analyzed for subcellular distribution of Cd, accumulation of mineral nutrients, photosynthesis, oxidative stress, protein content, and ultrastructural distribution of calcium (Ca). Leaf fractionation by differential centrifugation indicated that 48-69% of Cd was accumulated in the cell wall. At all doses of Cd, the levels of Ca and B rose and the level of Mn fell; the levels of Fe, Mg, Zn, Cu, Mo, and P rose initially only to decline later. Exposure to Cd caused oxidative stress as evident by increased content of malondialdehyde and decreased contents of chlorophyll and protein. Photosynthetic efficiency, as indicated by the quenching of chlorophyll a fluorescence (Fv/Fm, Fo and Fm), decreased significantly, the extent of decrease being directly proportional to the concentration of Cd. Increased amounts of precipitates of calcium were noticed in the treated plants, located either outside the cell membrane or in chloroplasts, mitochondria, the nucleus, and the cytoplasm whereas control plants showed small deposits of the precipitates around surface of the vacuole membrane and in the intercellular space but rarely in the cytoplasm. Photosynthetic efficiency and oxidative stress could be used as indicators of physiological end-points in determining the extent of Cd phytotoxicity.
authors.affiliation: Institute of Plant Cell and Molecular Biology, College of Life Science, Nanjing Normal University, Nanjing 210046, China. xuqinsong@163.com
authors.forename: Qinsong
authors.initials: Q
authors.lastname: Xu
authors.forename: Haili
authors.initials: H
authors.lastname: Min
authors.forename: Sanjuan
authors.initials: S
authors.lastname: Cai
authors.forename: Yongyang
authors.initials: Y
authors.lastname: Fu
authors.forename: Sha
authors.initials: S
authors.lastname: Sha
authors.forename: Kaibin
authors.initials: K
authors.lastname: Xie
authors.forename: Kaihe
authors.initials: K
authors.lastname: Du
mesh_terms: D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D002467:Cell Nucleus / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D002736:Chloroplasts / Q000378:metabolism; D008315:Malondialdehyde / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010788:Photosynthesis / Q000187:drug effects; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D031821:Potamogetonaceae / Q000187:drug effects* / Q000378:metabolism; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D002104:Cadmium; D002734:Chlorophyll; D008315:Malondialdehyde; D000077194:Chlorophyll A