Yan Yu-Wei, Mao Dan-Dan, Yang Lei, Qi Jin-Liang, Zhang Xin-Xin, Tang Qing-Lin, Li Yang-Ping, Tang Ren-Jie, Luan Sheng
Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States.
Key Laboratory of Biology and Genetic Improvement of Maize in Southwest Region, Maize Research Institute of Sichuan Agricultural University, Chengdu, China.
Front Plant Sci. 2018 Mar 12;9:274. doi: 10.3389/fpls.2018.00274. eCollection 2018.
Magnesium (Mg) is one of the essential nutrients for all living organisms. Plants acquire Mg from the environment and distribute within their bodies in the ionic form via Mg-permeable transporters. In , the plasma membrane-localized magnesium transporter MGT6 mediates Mg uptake under Mg-limited conditions, and therefore is important for the plant adaptation to low-Mg environment. In this study, we further assessed the physiological function of MGT6 using a knockout T-DNA insertional mutant allele. We found that MGT6 was required for normal plant growth during various developmental stages when the environmental Mg was low. Interestingly, in addition to the hypersensitivity to Mg limitation, mutants displayed dramatic growth defects when external Mg was in excess. Compared with wild-type plants, mutants generally contained less Mg under both low and high external Mg conditions. Reciprocal grafting experiments further underpinned a role of MGT6 in a shoot-based mechanism for detoxifying excessive Mg in the environment. Moreover, we found that double mutant showed more severe phenotypes compared with single mutants under both low- and high-Mg stress conditions, suggesting that these two MGT-type transporters play an additive role in controlling plant Mg homeostasis under a wide range of external Mg concentrations.
镁（Mg）是所有生物必需的营养元素之一。植物从环境中获取镁，并通过镁通透转运蛋白以离子形式在体内分布。在[具体情况未提及处]，质膜定位的镁转运蛋白MGT6在镁限制条件下介导镁的吸收，因此对植物适应低镁环境很重要。在本研究中，我们使用敲除型T-DNA插入突变等位基因进一步评估了MGT6的生理功能。我们发现，当环境镁含量低时，MGT6是植物在各个发育阶段正常生长所必需的。有趣的是，除了对镁限制高度敏感外，[突变体名称未提及]突变体在外部镁过量时也表现出明显的生长缺陷。与野生型植物相比，[突变体名称未提及]突变体在外部镁含量低和高的条件下通常含镁量都较少。相互嫁接实验进一步证实了MGT6在基于地上部的机制中对环境中过量镁进行解毒的作用。此外，我们发现[双突变体名称未提及]双突变体在低镁和高镁胁迫条件下比单突变体表现出更严重的表型，这表明这两种MGT型转运蛋白在广泛的外部镁浓度下对控制植物镁稳态发挥累加作用。
