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Cadmium impairs ion homeostasis by altering K + and Ca 2+ channel activities in rice root hair cells
Author(s) -
LI SUN,
YU JINGLING,
ZHU MINJIE,
ZHAO FUGENG,
LUAN SHENG
Publication year - 2012
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2012.02532.x
Subject(s) - chemistry , cadmium , homeostasis , biophysics , depolarization , membrane potential , ion transporter , root hair , calcium , potassium , ion channel , sodium , potassium channel , biochemistry , membrane , microbiology and biotechnology , biology , receptor , organic chemistry , gene
Cadmium (Cd 2+ ) interferes with the uptake, transport and utilization of several macro‐ and micronutrients, which accounts, at least in part, for Cd 2+ toxicity in plants. However, the mechanisms underlying Cd 2+ interference of ionic homeostasis is not understood. Using biophysical techniques including membrane potential measurements, scanning ion‐selective electrode technique for non‐invasive ion flux assays and patch clamp, we monitored the effect of Cd 2+ on calcium (Ca 2+ ) and potassium (K + ) transport in root hair cells of rice. Our results showed that K + and Ca 2+ contents in both roots and shoots were significantly reduced when treated with exogenous Cd 2+ . Further studies revealed that three cellular processes may be affected by Cd 2+ , leading to changes in ionic homeostasis. First, Cd 2+ ‐induced depolarization of the membrane potential was observed in root hair cells, attenuating the driving force for cation uptake. Second, the inward conductance of Ca 2+ and K + was partially blocked by Cd 2+ , decreasing uptake of K + and Ca 2+ . Third, the outward K + conductance was Cd 2+ ‐inducible, decreasing the net content of K + in roots. These results provide direct evidence that Cd 2+ impairs uptake of Ca 2+ and K + , thereby disturbing ion homeostasis in plants.