叶绿体镁转运蛋白OsCMT1调控水稻镁利用效率的分子机制

Magnesium (Mg) is a macronutrient essential for plant growth, which plays an especially important role in photosynthesis. Recently, with tremendous input of chemical fertilizers and increasing multi-cropping, plants are suffering Mg deficiency more prominently on the soil. Enhancing transport of Mg into plant especially into chloroplast could be the most effective way to increase Mg use efficiency in crop. Based on the previous work on screening of Mg hypersensitive mutants, we cloned a gene named OsCMT1 (Chloroplast-localized Magnesium Transporter 1), which encoded protein was localized at chloroplast envelope membrane system and was thought to be involved in Mg transport into chloroplast. In this study, we plan to clarify the mechanism for Mg transport in chloroplast through functional characterization of Mg transporter OsCMT1 from physiological, biochemical and molecular aspect. This study will provide the theoretical base for breeding cultivars with both high Mg use efficiency and high yield.

镁是植物生长和发育的必需营养元素之一，在光合过程中发挥至关重要的作用。随着化肥的大量施用以及复种指数的不断提高，作物缺镁问题日益突出。增强作物对镁离子的转运，尤其是镁向叶绿体的转运，是提高作物镁利用效率最为有效的途径之一。我们前期通过水稻镁敏感突变体的筛选，克隆到位于叶绿体膜上、负责镁向叶绿体转运的蛋白基因OsCMT1 (Chloroplast-localized Magnesium Transporter 1)。本研究首先将从生理、生化及分子层面，系统研究OsCMT1转运镁的生物学功能，解析镁在叶绿体中的运输机制，预期研究成果将为选育镁高效和高产的作物品种提供理论基础。

镁是植物生长和发育的必需营养元素之一，在光合过程中发挥至关重要的作用。增强作物对镁离子的转运，尤其是镁向叶绿体的转运，是提高作物镁利用效率最为有效的途径之一。然而，目前关于叶绿体镁转运的机制还不清楚。我们前期通过水稻镁敏感突变体的筛选，克隆到位于叶绿体膜上、负责镁向叶绿体转运的蛋白基因OsCMT1。通过生物学功能分析，发现该蛋白具有镁转运的功能，负责将镁离子从细胞质运输到叶绿体基质中。突变该基因后水稻光合速率降低，Vc,max 显著下降，说明了该基因的表达直接影响着植物光合效率以及暗反应中光合酶的活性。本课题研究的基因是目前植物叶绿体中发现的第一个镁吸收转运的基因。本研究进一步阐明了镁影响光合作用的调控机理。同时也为选育镁高效和高产的作物品种提供理论基础。