Ectopic expression of the K+ channel β subunits from Puccinellia tenuiflora (KPutB1) and rice (KOB1) alters K+ homeostasis of yeast and Arabidopsis

Mol Biotechnol. 2011 May;48(1):76-86. doi: 10.1007/s12033-010-9349-3.


In this study, we cloned a cDNA for the K+ channel β subunit from the halophyte Puccinellia tenuiflora and named it KPutB1. KPutB1 was preferentially expressed in the roots and was transiently induced by K+-starvation, salt stress, or the combination of both stresses. By yeast two-hybrid assay, we demonstrated that KPutB1 interacts with PutAKT1, α subunit of an AKT1-type K+ channel of P. tenuiflora. The functional relevance of this interaction on K+-nutrition was investigated by co-expression experiments in yeast under various ionic conditions, and K+ channel α and β subunit homologues from rice (OsAKT1 and KOB1, respectively) were included for comparison. Yeast co-expressing PutAKT1 and the β subunits (KPutB1 and KOB1) had better growth and higher K+-uptake ability than yeast expressing PutAKT1 alone. In contrast, yeast co-expressing the β subunits (KPutB1 and KOB1) with OsAKT1 had slower growth and lower K+ uptake than yeast expressing OsAKT1 alone. Arabidopsis plants over-expressing the K+ channel β subunit of P. tenuiflora or rice showed increased shoot K+ content and decreased root Na+ content under control, 75 mM NaCl, and K+-starvation stress conditions. These results suggest that ectopic expression of the K+ channel β subunit could alter K+ and Na+ homeostasis in plants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / metabolism*
  • Oryza / genetics*
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / metabolism
  • Poaceae / genetics*
  • Potassium / metabolism
  • Potassium Channels / genetics*
  • Potassium Channels / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Yeasts / genetics*
  • Yeasts / metabolism*


  • Potassium Channels
  • Potassium