A root-expressed magnesium transporter of the MRS2/MGT gene family in Arabidopsis thaliana allows for growth in Low-Mg2+ environments

Michael Gebert, Karoline Meschenmoser, Soňa Svidová, Julian Weghuber, Rudolf Schweyen, Karolin Eifler, Henning Lenz, Katrin Weyand, Volker Knoop

Research output: Contribution to journalArticlepeer-review

134 Citations (Scopus)

Abstract

The MRS2/MGT gene family in Arabidopsis thaliana belongs to the superfamily of CorA-MRS2-ALR-type membrane proteins. Proteins of this type are characterized by a GMN tripeptide motif (Gly-Met-Asn) at the end of the first of two C-terminal transmembrane domains and have been characterized as magnesium transporters. Using the recently established mag-fura-2 system allowing direct measurement of Mg2+ uptake into mitochondria of Saccharomyces cerevisiae, we find that all members of the Arabidopsis family complement the corresponding yeast mrs2 mutant. Highly different patterns of tissue-specific expression were observed for the MRS2/MGT family members in planta. Six of them are expressed in root tissues, indicating a possible involvement in plant magnesium supply and distribution after uptake from the soil substrate. Homozygous T-DNA insertion knockout lines were obtained for four members of the MRS2/MGT gene family. A strong, magnesium-dependent phenotype of growth retardation was found for mrs2-7 when Mg2+ concentrations were lowered to 50 μM in hydroponic cultures. Ectopic overexpression of MRS2-7 from the cauliflower mosaic virus 35S promoter results in complementation and increased biomass accumulation. Green fluorescent protein reporter gene fusions indicate a location of MRS2-7 in the endomembrane system. Hence, contrary to what is frequently found in analyses of plant gene families, a single gene family member knockout results in a strong, environmentally dependent phenotype.

Original languageEnglish
Pages (from-to)4018-4030
Number of pages13
JournalPlant Cell
Volume21
Issue number12
DOIs
Publication statusPublished - Dec 2009

Keywords

  • Arabidopsis/genetics
  • Arabidopsis Proteins/genetics
  • Cation Transport Proteins/genetics
  • Cloning, Molecular
  • DNA, Bacterial/genetics
  • Gene Expression Regulation, Plant
  • Gene Knockout Techniques
  • Genetic Complementation Test
  • Magnesium/metabolism
  • Multigene Family
  • Mutagenesis, Insertional
  • Mutation
  • Phylogeny
  • Plant Roots/genetics
  • Plants, Genetically Modified/genetics
  • RNA, Plant/genetics
  • Saccharomyces cerevisiae/metabolism
  • Tobacco/genetics
  • Nicotiana/genetics

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