Up-Regulation of a Magnesium Transporter Gene OsMGT1 Is Required for Conferring Aluminum Tolerance in Rice
Up-Regulation of a Magnesium Transporter Gene OsMGT1 Is Required for Conferring Aluminum Tolerance in Rice
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DOI：
10.1104/pp.112.199778
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发表时间：
2012-08-01
期刊：
影响因子：
7.4
通讯作者：
Ma, Jian Feng
中科院分区：
文献类型：
--
作者：
Chen, Zhi Chang;Yamaji, Naoki;Ma, Jian Feng
镁（Mg）介导的缓解铝（Al）毒性已被观察到在一些植物物种，但缓解的机制仍然知之甚少。当一个假定的水稻（Oryza sativa）镁转运蛋白基因，水稻镁转运蛋白1（OsMGT 1），被敲除，耐铝，但不镉和镧，下降。然而，这种抑制作用可以通过添加10 μ M的镁来挽救，但不能通过相同浓度的钡或锶来挽救。OsMGT 1在无铝胁迫下在根和地上部都有表达，但仅在根中表达被铝快速上调。此外，OsMGT 1的表达对低pH和镉、镧等重金属无反应，受铝应答转录因子AL RESISTANCE TRANSPITION FACTOR 1调控。亚细胞定位的研究表明，OsMGT 1定位于质膜。利用稳定同位素Mg-25进行的短期（30 min）吸收实验表明，OsMGT 1敲除导致Mg吸收减少，但野生型中的吸收被Al增强。基因芯片分析表明，与胁迫相关的基因转录本在敲除株系中表达上调和下调。综上所述，我们的研究结果表明，OsMGT 1是一个转运镁吸收在根中，该基因的上调是必需的，通过提高细胞中的镁浓度赋予水稻耐铝。
Magnesium (Mg)-mediated alleviation of aluminum (Al) toxicity has been observed in a number of plant species, but the mechanisms underlying the alleviation are still poorly understood. When a putative rice (Oryza sativa) Mg transporter gene, Oryza sativa MAGNESIUM TRANSPORTER1 (OsMGT1), was knocked out, the tolerance to Al, but not to cadmium and lanthanum, was decreased. However, this inhibition could be rescued by addition of 10 mu M Mg, but not by the same concentration of barium or strontium. OsMGT1 was expressed in both the roots and shoots in the absence of Al, but the expression only in the roots was rapidly up-regulated by Al. Furthermore, the expression did not respond to low pH and other metals including cadmium and lanthanum, and was regulated by an Al-responsive transcription factor, AL RESISTANCE TRANSCRIPTION FACTOR1. An investigation of subcellular localization showed that OsMGT1 was localized to the plasma membrane. A short-term (30 min) uptake experiment with stable isotope Mg-25 showed that knockout of OsMGT1 resulted in decreased Mg uptake, but that the uptake in the wild type was enhanced by Al. Mg concentration in the cell sap of the root tips was also increased in the wild-type rice, but not in the knockout lines in the presence of Al. A microarray analysis showed that transcripts of genes related to stress were more up- and down-regulated in the knockout lines. Taken together, our results indicate that OsMGT1 is a transporter for Mg uptake in the roots and that up-regulation of this gene is required for conferring Al tolerance in rice by increasing Mg concentration in the cell.