title: Chemical speciation and cellular deposition of lead in Sesbania drummondii.
abstract: The internalized speciation of lead in roots and leaves of Sesbania drummondii, a lead hyperaccumulator, grown in lead nitrate solution was studied using x-ray absorption near-edge structure and extended x-ray absorption fine structure. Lead was predominantly present as lead acetate in both plant tissues. The other dominant forms of accumulation were lead-sulfur compounds. Whereas lead sulfate and sulfide were found in leaves, only lead sulfide was detected in root samples. These observations indicate that S. drummondii is able to biotransform lead nitrate in the nutrient solution to lead acetate and sulfate in its tissues. Complexation with acetate and sulfate may be a lead detoxification strategy in this plant. Transmission-electron microscopy revealed the pattern of lead distribution in and around the cells. Dense distributions of lead grains were detected in root cell walls and plasma membranes, whereas evidence for vacuolar transport of lead was noticed in the stem cells.
authors.affiliation: Biotechnology Center, Department of Biology, Western Kentucky University, Bowling Green, Kentucky 42101, USA.
authors.forename: Nilesh C
authors.initials: NC
authors.lastname: Sharma
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Gardea-Torresdey
authors.forename: Jason
authors.initials: J
authors.lastname: Parsons
authors.forename: Shivendra V
authors.initials: SV
authors.lastname: Sahi
mesh_terms: D004577:Electron Probe Microanalysis; D007887:Fabaceae / Q000737:chemistry / Q000378:metabolism*; D007854:Lead / Q000032:analysis / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D009942:Organometallic Compounds / Q000032:analysis; D018515:Plant Leaves / Q000737:chemistry / Q000378:metabolism; D018517:Plant Roots / Q000737:chemistry / Q000378:metabolism; D036226:Seedlings / Q000737:chemistry / Q000378:metabolism; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism*; D013440:Sulfides / Q000032:analysis; D014481:United States; D018505:Waste Management / Q000379:methods
chemical_list: D009942:Organometallic Compounds; D012989:Soil Pollutants; D013440:Sulfides; C018391:lead sulfide; D007854:Lead; C032722:lead sulfate; C008261:lead acetate