Overexpression of a new putative membrane protein gene AtMRB1 results in organ size enlargement in Arabidopsis

J Integr Plant Biol. 2009 Feb;51(2):130-9. doi: 10.1111/j.1744-7909.2008.00795.x.


Arabidopsis AtMRB1 is predicted to encode a novel protein of 432 amino acid residues in length, with four putative trans-membrane domains. In the present study, characterization of AtMRB1 is conducted. Green fluorescent protein (GFP) fusion protein assay showed that AtMRB1 was located in the plasma membrane. Transgenic lines overexpressing AtMRB1 driven by a CaMV 35S promoter were generated. Statistic analysis showed that, during the seedling stage, the organ sizes of the transgenic lines including hypocotyl length, root length and root weight were significantly larger than those of the wild type plants under both light and dark conditions. In the adult plant stage, the AtMRB1 overexpressor plants were found to have larger organ sizes in terms of leaf length and width, and increased number of cauline leaves and branches when bolting. Further observation indicated that the larger leaf size phenotype was due to a larger number of mesophyll cells, the size of which was not altered. Quantitative real-time polymerase chain reaction analysis showed that the transcription of ANT, ROT3 and GRF5 were upregulated in the AtMRB1-overexpressor plants. These data suggest that AtMRB1 is possibly a positive regulator of organ size development in Arabidopsis, mainly through cell number control.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 14-3-3 Proteins
  • Amino Acid Sequence
  • Arabidopsis / genetics
  • Arabidopsis / growth & development*
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cell Membrane / metabolism*
  • Cell Proliferation*
  • Cytochrome P-450 Enzyme System / metabolism
  • Gene Expression Regulation, Plant
  • Green Fluorescent Proteins / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Molecular Sequence Data
  • Plant Leaves / growth & development
  • Plant Roots / growth & development
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / growth & development
  • Plants, Genetically Modified / metabolism
  • Polymerase Chain Reaction
  • RNA, Plant / genetics
  • Sequence Alignment
  • Trans-Activators / metabolism
  • Transcription Factors / metabolism


  • 14-3-3 Proteins
  • AINTEGUMENTA protein, Arabidopsis
  • Arabidopsis Proteins
  • GRF5 protein, Arabidopsis
  • MRB1 protein, Arabidopsis
  • Membrane Proteins
  • RNA, Plant
  • Trans-Activators
  • Transcription Factors
  • Green Fluorescent Proteins
  • Cytochrome P-450 Enzyme System
  • ROT3 protein, Arabidopsis