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Journal of Tea Science ›› 2021, Vol. 41 ›› Issue (6): 761-776.

• Research Paper • Previous Articles     Next Articles

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

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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