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Root development under metal stress in Arabidopsis thaliana requires the H + /cation antiporter CAX4
Author(s) -
Mei Hui,
Cheng Ning Hui,
Zhao Jian,
Park Sunghun,
Escareno Rito A.,
Pittman Jon K.,
Hirschi Kendal D.
Publication year - 2009
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.2009.02831.x
Subject(s) - antiporter , arabidopsis , vacuole , auxin , mutant , arabidopsis thaliana , root hair , microbiology and biotechnology , sodium–hydrogen antiporter , biology , lateral root , chemistry , botany , biochemistry , gene , cytoplasm , membrane , sodium , organic chemistry
Summary• The Arabidopsis vacuolar CA tion e X changers (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.