Phytoremediation of organomercurial compounds via chloroplast genetic engineering
Phytoremediation of organomercurial compounds via chloroplast genetic engineering
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DOI：
10.1104/pp.103.020958
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发表时间：
2003-07-01
期刊：
影响因子：
7.4
通讯作者：
Daniell, H
中科院分区：
文献类型：
--
作者：
Ruiz, ON;Hussein, HS;Daniell, H
汞（Hg），特别是有机汞，是一种毒性很强的污染物，对植物、动物和人类都有很大影响。在植物中，汞损害的主要目标是叶绿体;汞抑制电子传递和光合作用。在本研究中，叶绿体基因工程是第一次使用到我们的知识，以提高植物的植物修复能力。这是通过将含有merA和merB基因（没有任何密码子修饰）的天然操纵子（分别编码汞离子还原酶（merA）和有机汞裂解酶（merB））整合到叶绿体基因组中来实现的。稳定整合的merAB操纵子到叶绿体基因组中导致高水平的耐受性的有机汞化合物，苯汞乙酸（PMA）生长在土壤中含有高达400 μ M的PMA时，叶绿体转化株系的植物干重显着高于野生型在100，200，和400 μ M PMA。聚合酶链反应和Southern-blot分析证实merAB操纵子稳定整合到叶绿体基因组中。Northern-blot分析显示稳定的转录本，其独立于编码序列下游的3 '-非翻译区的存在或不存在。merAB双顺反子是更丰富的转录物，但也观察到不太丰富的单顺反子，表明转基因之间发生特异性加工。利用叶绿体转化来增强汞的植物修复是特别有益的，因为它可以防止转基因通过花粉逃逸到相关的杂草或作物中，并且不需要密码子优化来提高转基因的表达。叶绿体转化也可以应用于影响叶绿体功能的其他金属。
Mercury (Hg), especially in organic form, is a highly toxic pollutant affecting plants, animals, and man. In plants, the primary target of Hg damage is the chloroplast; Hg inhibits electron transport and photosynthesis. In the present study, chloroplast genetic engineering is used for the first time to our knowledge to enhance the capacity of plants for phytoremediation. This was achieved by integrating a native operon containing the merA and merB genes (without any codon modification), which code for mercuric ion reductase (merA) and organomercurial lyase (merB), respectively, into the chloroplast genome in a single transformation event. Stable integration of the merAB operon into the chloroplast genome resulted in high levels of tolerance to the organomercurial compound, phenylmercuric acetate (PMA) when grown in soil containing up to 400 muM PMA; plant dry weights of the chloroplast transformed lines were significantly higher than those of wild type at 100, 200, and 400 muM PMA. That the merAB operon was stably integrated into the chloroplast genome was confirmed by polymerase chain reaction and Southern-blot analyses. Northern-blot analyses revealed stable transcripts that were independent of the presence or absence of a 3'-untranslated region downstream of the coding sequence. The merAB dicistron was the more abundant transcript, but less abundant monocistrons were also observed, showing that specific processing occurs between transgenes. The use of chloroplast transformation to enhance Hg phytoremediation is particularly beneficial because it prevents the escape of transgenes via pollen to related weeds or crops and there is no need for codon optimization to improve transgene expression. Chloroplast transformation may also have application to other metals that affect chloroplast function.