A DNA Methylation Reader-Chaperone Regulator-Transcription Factor Complex Activates OsHKT1;5 Expression during Salinity Stress

Plant Cell. 2020 Nov;32(11):3535-3558. doi: 10.1105/tpc.20.00301. Epub 2020 Sep 15.


Irrigated lands are increasingly salinized, which adversely affects agricultural productivity. To respond to high sodium (Na+) concentrations, plants harbor multiple Na+ transport systems. Rice (Oryza sativa) HIGH-AFFINITY POTASSIUM (K+) TRANSPORTER1;5 (OsHKT1;5), a Na+-selective transporter, maintains K+/Na+ homeostasis under salt stress. However, the mechanism regulating OsHKT1;5 expression remains unknown. Here, we present evidence that a protein complex consisting of rice BCL-2-ASSOCIATED ATHANOGENE4 (OsBAG4), OsMYB106, and OsSUVH7 regulates OsHKT1;5 expression in response to salt stress. We isolated a salt stress-sensitive mutant, osbag4-1, that showed significantly reduced OsHKT1;5 expression and reduced K+ and elevated Na+ levels in shoots. Using comparative interactomics, we isolated two OsBAG4-interacting proteins, OsMYB106 (a MYB transcription factor) and OsSUVH7 (a DNA methylation reader), that were crucial for OsHKT1;5 expression. OsMYB106 and OsSUVH7 bound to the MYB binding cis-element (MYBE) and the miniature inverted-repeat transposable element (MITE) upstream of the MYBE, respectively, in the OsHKT1;5 promoter. OsBAG4 functioned as a bridge between OsSUVH7 and OsMYB106 to facilitate OsMYB106 binding to the consensus MYBE in the OsHKT1;5 promoter, thereby activating the OsHKT1;5 expression. Elimination of the MITE or knockout of OsMYB106 or OsSUVH7 decreased OsHKT1;5 expression and increased salt sensitivity. Our findings reveal a transcriptional complex, consisting of a DNA methylation reader, a chaperone regulator, and a transcription factor, that collaboratively regulate OsHKT1;5 expression during salinity stress.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • CRISPR-Cas Systems
  • DNA Methylation*
  • DNA Transposable Elements
  • DNA, Plant / metabolism
  • Gene Expression Regulation, Plant
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / metabolism
  • Oryza / genetics
  • Oryza / physiology*
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plants, Genetically Modified
  • Promoter Regions, Genetic
  • Salt Stress / genetics*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism


  • DNA Transposable Elements
  • DNA, Plant
  • Molecular Chaperones
  • Multiprotein Complexes
  • Plant Proteins
  • Transcription Factors