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茶叶科学 ›› 2021, Vol. 41 ›› Issue (6): 761-776.

• 研究报告 • 上一篇    下一篇

茶树CsMGTs基因的克隆及其镁转运功能分析

唐磊, 肖罗丹, 黄伊凡, 肖斌, 龚春梅*   

  1. 西北农林科技大学园艺学院,陕西 杨凌 712100
  • 收稿日期:2020-12-07 修回日期:2021-05-05 出版日期:2021-12-15 发布日期:2021-12-09
  • 通讯作者: *gcm228@nwafu.edu.cn
  • 作者简介:唐磊,男,博士研究生,主要从事茶树生理与分子生物学研究,1938170872@qq.com。
  • 基金资助:
    陕西省重点研发计划项目(2020NY-190)

Cloning and Magnesium Transport Function Analysis of CsMGTs Genes in Tea Plants (Camellia sinensis)

TANG Lei, XIAO Luodan, HUANG Yifan, XIAO Bin, GONG Chunmei*   

  1. College of Horticulture, Northwest Agriculture and Forestry University, Yangling 712100, China
  • Received:2020-12-07 Revised:2021-05-05 Online:2021-12-15 Published:2021-12-09

摘要: 镁离子(Mg2+)作为叶绿素的中心成分,是植物细胞中含量最丰富的二价阳离子,也是多种酶的激活剂,特别是茶氨酸合成酶的活性依赖Mg2+,常被作为茶树专用肥的特征成分,因此对茶树的生长发育和茶叶的品质形成至关重要。MRS2/MGT家族镁转运蛋白在维持植物体内Mg2+的吸收转运、胞内平衡和耐逆性等方面起着重要的作用。为探究茶树MRS2/MGT家族镁转运蛋白基因的功能,以茶树品种陕茶1号为材料,克隆了4条MRS2/MGT镁转运蛋白基因,分别命名为CsMGT1CsMGT2CsMGT2.1CsMGT3。生物信息学分析表明,这4个转运蛋白在C末端均含有2个跨膜结构域和1个保守的GMN三肽基序;系统发育分析显示,CsMGT1属于Clade C成员,而CsMGT2CsMGT2.1CsMGT3属于Clade B成员,所编码蛋白与木本植物柑橘MGT家族的亲缘关系最近。实时荧光定量PCR(qRT-PCR)分析表明,CsMGT1CsMGT2CsMGT2.1CsMGT3在茶树的根、茎、叶、花中呈组成型表达,且根和叶对Mg2+浓度均表现出不同程度的响应。鼠伤寒沙门氏菌镁转运缺失突变株MM281功能互补试验表明,CsMGT1和CsMGT2均具有Mg2+转运功能,且CsMGT1的Mg2+转运功能优于CsMGT2,而CsMGT2.1和CsMGT3几乎没有镁离子转运功能。本研究结果丰富了茶树CsMGTs家族的生物学功能,为进一步阐明茶树通过镁转运功能机制实现对镁离子的利用奠定了前期研究基础。

关键词: 茶树, MRS2/MGT, 基因克隆, 表达模式, 功能分析

Abstract: Magnesium (Mg2+), as the central atom of chlorophyll, is the most abundant divalent cation in plant cells. Magnesium is also an activator of various enzymes, especially theanine synthase, whose activity depends on Mg2+ concentration and is often used as a characteristic component of special fertilizer for tea plants. Therefore, it is very important for both the growth and development of tea plants and the formation of tea quality. The MRS2/MGT magnesium transporter family plays an important role in maintaining the absorption and transport of Mg2+, intracellular balance and stress tolerance in plants. In order to explore the functions of the MRS2/MGT magnesium transport genes in tea plants, this study cloned four MRS2/MGT magnesium transporter genes (namely CsMGT1, CsMGT2, CsMGT2.1 and CsMGT3, respectively) from tea cultivar ‘Shaancha 1'. Bioinformatics analysis shows that the four proteins all contain two transmembrane domains and a conserved GMN tripeptide motif at the C-terminal. Phylogenetic analysis shows that CsMGT1 is a member of Clade C, while CsMGT2, CsMGT2.1 and CsMGT3 belong to Clade B, and the four encoded proteins are most closely related to the woody Poncirus trifoliata MGT family. Real-time fluorescence quantitative PCR (RT-qPCR) shows that CsMGT1, CsMGT2, CsMGT2.1 and CsMGT3 were constitutively expressed in the roots, stems, leaves and flowers of tea plants, and the roots and leaves all showed different degrees of response to Mg2+. Functional complementation tests in a magnesium deletion mutant strain MM281 of Salmonella typhimurium show that both CsMGT1 and CsMGT2 possessed Mg2+ transport function, and the Mg2+ transport function of CsMGT1 was superior to that of CsMGT2, while CsMGT2.1 and CsMGT3 had almost no Mg2+ transport function. The results of this study enriched the biological functions of tea plant CsMGTs family, and laid a foundation for further utilization of magnesium through magnesium transporters in tea plants.

Key words: tea plant, MRS2/MGT, gene cloning, expression pattern, function analysis

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