芒萁的器官-亚细胞稀土分布特征及耐受阈值

Distribution characteristics and tolerance threshold of organ-subcellular rare earth elements in Dicranopteris pedata

  • 摘要: 芒萁是目前已知的最强稀土超富集植物, 但其对稀土的耐受机制尚未探明。本研究以矿区芒萁为研究对象, 开展代表性稀土元素铈、钇的添加实验, 分析芒萁在不同稀土浓度下, 其不同器官及各亚细胞组分中的稀土富集特征。结果表明: 1)芒萁体内铈元素总量随稀土浓度增加而增加, 而对钇元素最大耐受浓度为0.8 mmol/L; 2)当铈、钇浓度≤0.8 mmol/L时, 芒萁各器官稀土含量为叶片>根茎>叶柄, 而浓度为1.6 mmol/L时各器官钇含量为叶柄>叶片>根茎、铈含量为根茎>叶片>叶柄; 3)芒萁对轻稀土铈元素的富集系数大于重稀土钇的富集系数; 4)芒萁叶片和根中的铈和钇分布于细胞壁的占比最大, 且叶片细胞壁中铈、钇含量占比随着添加稀土浓度的增加呈上升趋势; 5)芒萁叶柄各亚细胞组分中铈、钇含量占比在低浓度和高浓度下存在显著差异。芒萁对稀土元素具有较强的耐受性和富集能力, 其地上部分(尤其是叶片)通过区室化隔离作用有效调控稀土分布, 且对轻稀土铈的富集能力强于重稀土钇; 细胞壁是稀土积累的关键部位, 在不同稀土浓度的胁迫下, 芒萁各器官对稀土的耐受响应特征存在显著差异。本研究成果可为利用稀土超富集植物芒萁进行土壤稀土污染修复提供理论依据。

     

    Abstract: Dicranopteris pedata is the strongest rare earth hyperaccumulator known to date, but its tolerance to rare earths has not been elucidated. In this study, Dicranopteris pedata in the mining area was taken as the research object, and the addition experiments of representative rare earth elements cerium and yttrium were carried out to analyze the rare earth enrichment characteristics of different organs and subcellular components of Dicranopteris pedata under different rare earth concentrations. The results showed that: 1) The total amount of cerium in Dicranopteris pedata increased with the increase of rare earth concentration, and the maximum tolerance concentration of yttrium was 0.8 mmol/L. 2) When the concentration of cerium and yttrium was ≤ 0.8 mmol/L, the rare earth content in each organ of Dicranopteris pedata was leaf > rhizome > petiole, while the concentration was 1.6mmol/L, the yttrium content in various organs was petiole > leaf > rhizome, and the cerium content was rhizome > leaf > petiole. 3) The enrichment coefficient of light rare earth cerium is greater than that of heavy rare earth yttrium. 4) Cerium and yttrium in the leaves and roots of Dicranopteris pedata distributed in the cell wall accounted for the largest proportion, and the proportion of cerium and yttrium in the leaf cell wall increased with the increase of rare earth concentration. 5) There were significant differences in the proportion of cerium and yttrium in the subcellular components of Dicranopteris pedata petioles at low and high concentrations. Dicranopteris pedata has strong tolerance and enrichment ability to rare earth elements. The aboveground part (especially the leaves) of Dicranopteris pedata can effectively regulate the distribution of rare earth elements through compartmentalization isolation, and the enrichment ability of light rare earth cerium is stronger than that of heavy rare earth yttrium. The cell wall is the key part of rare earth accumulation, under the stress of different concentrations of rare earth elements, the tolerance response characteristics of each organ of Dicranopteris pedata to rare earth elements show significant differences. The results of this study can provide a theoretical basis for the remediation of soil rare earth pollution by using rare earth hyperaccumulator Dicranopteris pedata.

     

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