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Spatial variation in H2O2 response of Arabidopsis thaliana root epidermal Ca2+ flux and plasma membrane Ca2+ channels
被引:172
作者:
Demidchik, Vadim
Shabala, Sergey N.
Davies, Julia M.
机构:
[1] Univ Cambridge, Dept Plant Sci, Cambridge CB2 3EA, England
[2] Univ Tasmania, Sch Agr Sci, Hobart, Tas 7001, Australia
关键词:
hydrogen peroxide;
calcium;
channel;
root;
epidermis;
D O I:
10.1111/j.1365-313X.2006.02971.x
中图分类号:
Q94 [植物学];
学科分类号:
071001 ;
摘要:
Hydrogen peroxide is an important regulatory agent in plants. This study demonstrates that exogenous H2O2 application to Arabidopsis thaliana root epidermis results in dose-dependent transient increases in net Ca2+ influx. The magnitude and duration of the transients were greater in the elongation zone than in the mature epidermis. In both regions, treatment with the cation channel blocker Gd3+ prevented H2O2-induced net Ca2+ influx, consistent with application of exogenous H2O2 resulting in the activation of plasma membrane Gd3+-sensitive Ca2+-influx pathways. Application of 10 mM H2O2 to the external plasma membrane face of elongation zone epidermal protoplasts resulted in the appearance of a hyperpolarization-activated Ca2+-permeable conductance. This conductance differed from that previously characterized as being responsive to extracellular hydroxyl radicals. In contrast, in mature epidermal protoplasts a plasma membrane hyperpolarization-activated Ca2+-permeable channel was activated only when H2O2 was present at the intracellular membrane face. Channel open probability increased with intracellular [H2O2] and at hyperpolarized voltages. Unitary conductance decreased thus: Ba2+ > Ca2+ (14.5 pS) > Mg2+ > Zn2+ (20 M external cation, 1 mMH(2)O(2)). Lanthanides and Zn2+ (but not TEA(+)) suppressed the open probability without affecting current amplitude. The results suggest spatial heterogeneity and differential sensitivity of Ca2+ channel activation by reactive oxygen species in the root that could underpin signalling.
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页码:377 / 386
页数:10
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