Root development under metal stress in Arabidopsis thaliana requires the H+/cation antiporter CAX4

New Phytol. 2009;183(1):95-105. doi: 10.1111/j.1469-8137.2009.02831.x. Epub 2009 Apr 8.


* The Arabidopsis vacuolar CAtion eXchangers (CAXs) play a key role in mediating cation influx into the vacuole. In Arabidopsis, there are six CAX genes. However, some members are yet to be characterized fully. * In this study, we show that CAX4 is expressed in the root apex and lateral root primordia, and that expression is increased when Ni(2+) or Mn(2+) levels are elevated or Ca(2+) is depleted. * Transgenic plants expressing increased levels of CAX4 display symptoms consistent with increased sequestration of Ca(2+) and Cd(2+) into the vacuole. When CAX4 is highly expressed in an Arabidopsis cax1 mutant line with weak vacuolar Ca(2+)/H(+) antiport activity, a 29% increase in Ca(2+)/H(+) antiport is measured. A cax4 loss-of-function mutant and CAX4 RNA interference lines display altered root growth in response to Cd(2+), Mn(2+) and auxin. The DR5::GUS auxin reporter detected reduces auxin responses in the cax4 lines. * These results indicate that CAX4 is a cation/H(+) antiporter that plays an important function in root growth under heavy metal stress conditions.

Publication types

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

MeSH terms

  • Adaptation, Physiological / genetics*
  • Antiporters / genetics
  • Antiporters / metabolism*
  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Cation Transport Proteins / genetics
  • Cation Transport Proteins / metabolism*
  • Gene Expression
  • Gene Expression Regulation, Plant
  • Indoleacetic Acids / metabolism
  • Metals, Heavy / metabolism*
  • Metals, Heavy / toxicity
  • Mutation
  • Plant Roots / drug effects
  • Plant Roots / genetics
  • Plant Roots / growth & development
  • Plant Roots / metabolism*
  • Plants, Genetically Modified / genetics
  • Plants, Genetically Modified / growth & development
  • Plants, Genetically Modified / metabolism*
  • Stress, Physiological / genetics
  • Vacuoles / metabolism


  • Antiporters
  • Arabidopsis Proteins
  • CAX4 protein, Arabidopsis
  • Cation Transport Proteins
  • Indoleacetic Acids
  • Metals, Heavy