Sousa Ana I, Caçador Isabel, Lillebø Ana I, Pardal Miguel A
Faculty of Sciences, University of Lisbon, Campo Grande, 1749-016 Lisbon, Portugal.
Chemosphere. 2008 Jan;70(5):850-7. doi: 10.1016/j.chemosphere.2007.07.012. Epub 2007 Aug 30.
Salt marsh plants can sequestrate and inherently tolerate high metal concentrations found in salt marsh sediments. This work intended to understand the Halimione portulacoides (L.) Aellen strategies to prevent metal toxicity, by investigating the metal location in different plant organs and in the cell. A sequential extraction was performed on leaves, stems and roots of H. portulacoides in order to determine and compare the metal (Zn, Pb, Co, Cd, Ni and Cu) concentration in several fractions of the plant material (ethanolic, aqueous, proteic, pectic, polissacaridic, lenhinic and cellulosic). This study shows that all plant organs of H. portulacoides mostly retain metals in the cell wall (65% is the average for all studied metals stored in the root cell wall, 55% in the stems and 53% in the leaves), and the metal content in the intracellular compartment is much lower (21% in roots, 25% in stems and 32% in leaves). High levels of heavy metal in the sedimentary environment do not cause toxicity to H. portulacoides, because H. portulacoides immobilizes them in different cell compartments (cell wall+proteic fraction+intracellular) outside key metabolic sites.
盐沼植物能够吸收并天然耐受盐沼沉积物中高浓度的金属。这项研究旨在通过调查不同植物器官及细胞中的金属分布情况，来了解海滨碱蓬防止金属毒性的策略。对海滨碱蓬的叶、茎和根进行了连续萃取，以测定并比较植物材料不同组分（乙醇提取物、水提取物、蛋白质、果胶、多糖、木质素和纤维素）中的金属（锌、铅、钴、镉、镍和铜）浓度。该研究表明，海滨碱蓬的所有植物器官大多将金属保留在细胞壁中（所有研究金属储存在根细胞壁中的平均比例为65%，茎中为55%，叶中为53%），而细胞内部分的金属含量则低得多（根中为21%，茎中为25%，叶中为32%）。沉积环境中的高浓度重金属不会对海滨碱蓬造成毒性，因为海滨碱蓬将它们固定在关键代谢位点之外的不同细胞区室（细胞壁+蛋白质部分+细胞内）中。
