Expression of Arabidopsis CAX1 in tobacco: altered calcium homeostasis and increased stress sensitivity

Plant Cell. 1999 Nov;11(11):2113-22. doi: 10.1105/tpc.11.11.2113.


Calcium (Ca(2)+) efflux from the cytosol modulates Ca(2+) concentrations in the cytosol, loads Ca(2+) into intracellular compartments, and supplies Ca(2+) to organelles to support biochemical functions. The Ca(2+)/H(+) antiporter CAX1 (for CALCIUM EXCHANGER 1) of Arabidopsis is thought to be a key mediator of these processes. To clarify the regulation of CAX1, we examined CAX1 RNA expression in response to various stimuli. CAX1 was highly expressed in response to exogenous Ca(2+). Transgenic tobacco plants expressing CAX1 displayed symptoms of Ca(2+) deficiencies, including hypersensitivity to ion imbalances, such as increased magnesium and potassium concentrations, and to cold shock, but increasing the Ca(2+) in the media abrogated these sensitivities. Tobacco plants expressing CAX1 also demonstrated increased Ca(2+) accumulation and altered activity of the tonoplast-enriched Ca(2+)/H(+) antiporter. These results emphasize that regulated expression of Ca(2+)/H(+) antiport activity is critical for normal growth and adaptation to certain stresses.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antiporters / genetics*
  • Antiporters / metabolism*
  • Arabidopsis / genetics*
  • Arabidopsis / metabolism*
  • Calcium / metabolism
  • Calcium-Binding Proteins / genetics*
  • Calcium-Binding Proteins / metabolism*
  • Cation Transport Proteins*
  • Homeostasis
  • Organelles / metabolism
  • Plant Roots / metabolism
  • Plants, Genetically Modified
  • Plants, Toxic*
  • Tobacco / genetics
  • Tobacco / physiology*


  • Antiporters
  • Calcium-Binding Proteins
  • Cation Transport Proteins
  • calcium-hydrogen antiporters
  • Calcium