巴西橡胶树镁离子转运蛋白基因HbMGT10的克隆及表达分析

Molecular Cloning and Expression Analysis of HbMGT10 from Hevea brasiliensis

Mg^(2+)是植物细胞中含量最高的二价阳离子,是多种酶活性调控的辅因子,在植物的生长发育过程中发挥重要作用;同时,作为叶绿素分子的中心原子,在植物光合作用中起着至关重要的作用,但目前有关高大乔木叶片中Mg^(2+)跨膜运输的研究还很少。MGT/MRS2类型的镁离子转运蛋白在植物镁离子的跨膜运输过程中起着重要的作用,本文克隆研究了一个巴西橡胶树MGT基因,HbMGT10。亚细胞定位显示,HbMGT10定位于叶绿体膜上;酵母互补实验表明,HbMGT10具有镁离子转运功能;qRT-PCR分析结果显示,HbMGT10主要在橡胶树叶片中表达,且是叶片中表达丰度最高的HbMGT基因;HbMGT10在叶片中的表达存在明显的发育调控,随叶片发育进程表达量明显增加,在淡绿期和稳定期表达量最大;HbMGT10在成熟叶片中的表达呈现明显的日变化,在光强度最大的12:00~16:00的表达量最大。由此推测,HbMGT10在橡胶树叶片叶绿体膜的镁离子跨膜转运过程中起着重要的作用,参与了橡胶树叶片叶绿体的发育,以及叶绿体中镁离子浓度的调控,以适应橡胶树叶片的光合作用。

Mg^2＋is the most abundant divalent cation ion in plant cells, which plays crucial roles in plant growth and development through regulating the activities of a plethora of enzymes. In addition, as the central atom of the chlorophyll molecule, Mg^2＋plays a vital role in plant photosynthesis, but Mg^2＋transmembrance transport in the leaves of big trees is seldom researched. MGT/MRS2 type magnesium transporters play important roles during the process of Mg^2＋transmembrance transport in plants. In this study, a MGT gene, HbMGT10, was first cloned and characterized in Hevea brasiliensis. HbMGT10 was located in the chloroplast as shown by a transient subsellular localization analysis. HbMGT10 could transport Mg^2＋as verified by a yeast complementary experiment. qRT-PCR revealed that HbMGT10 was expressed mainly in Hevea leaves, and was also the most abundant HbMGT isoform in this organ. Expressions of HbMGT10 accumulated with the process of Hevea leaf development, plateauing at light green and stable stages. HbMGT10 expressions showed an apparent diurnal change, being much higher from12 ： 00 to 16 ： 00 in coincidence with the highest light intensity of the day. It is speculated that HbMGT10 plays an active role in regulating the concentrations of magnesium in chloroplast, and participates in chloroplast development and photosynthesis of H. brasiliensis.