Válega M, Lima A I G, Figueira E M A P, Pereira E, Pardal M A, Duarte A C
CESAM and Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal.
Chemosphere. 2009 Jan;74(4):530-6. doi: 10.1016/j.chemosphere.2008.09.076. Epub 2008 Nov 11.
In the presence of metal stress, plants can resort to a series of tolerance mechanisms. Therefore field studies should be undertaken in order to evaluate the real role of these mechanisms in stress coping. The aim of this paper was to clarify the biochemical processes behind mercury tolerance in Halimione portulacoides (L.) Aellen (Caryophyllales: Chenopodiaceae) collected in a mercury contaminated salt marsh. Different fractions of mercury were separated: buffer-soluble (mainly cytosolic) and insoluble mercury (mainly associated with membranes and cell walls). The amounts in each fraction of metal were compared and related to metal distribution within plant organs. Protein-mercury complexes were isolated and analysed for their thiol content in order to assess wether the tolerance of this salt marsh plant was associated with the induction of metal chelation by phytochelatins. Overall, the mercury tolerance strategies of the plant are likely to involve root cell wall immobilization as a major mechanism of metal resistance, rather than metal chelation in the cytosolic fraction. Nevertheless, phytochelatins were demonstrated to chelate mercury under environmental exposure.
在金属胁迫存在的情况下，植物可以采用一系列耐受机制。因此，应该进行田间研究，以评估这些机制在应对胁迫中的实际作用。本文的目的是阐明在汞污染盐沼中采集的海滨碱蓬（石竹目：藜科）对汞耐受背后的生化过程。分离了不同部分的汞：缓冲液可溶性汞（主要存在于细胞质中）和不溶性汞（主要与膜和细胞壁结合）。比较了各部分金属的含量，并将其与植物器官内的金属分布相关联。分离出蛋白质 - 汞复合物并分析其硫醇含量，以评估这种盐沼植物的耐受性是否与植物螯合肽诱导的金属螯合作用有关。总体而言，该植物的汞耐受策略可能涉及根细胞壁固定化作为金属抗性的主要机制，而不是细胞质部分中的金属螯合作用。然而，已证明植物螯合肽在环境暴露下会螯合汞。
