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Spatial variation in H2O2 response of Arabidopsis thaliana root epidermal Ca2+ flux and plasma membrane Ca2+ channels

Demidchik, V, Shabala, SN and Davies, JM 2007 , 'Spatial variation in H2O2 response of Arabidopsis thaliana root epidermal Ca2+ flux and plasma membrane Ca2+ channels' , The Plant Journal, vol. 49, no. 3 , pp. 377-386 , doi:

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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 Ca2þ
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 Gd3þ prevented H2O2-induced net Ca2þ
influx, consistent with application of exogenous H2O2 resulting in the activation of plasma membrane Gd3þsensitive
Ca2þ-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 Ca2þpermeable
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 Ca2þ-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: Ba2þ > Ca2þ (14.5 pS) > Mg2þ > Zn2þ (20 mM external cation, 1 mM
H2O2). Lanthanides and Zn2þ (but not TEAþ) suppressed the open probability without affecting current
amplitude. The results suggest spatial heterogeneity and differential sensitivity of Ca2þ channel activation by
reactive oxygen species in the root that could underpin signalling.

Item Type: Article
Authors/Creators:Demidchik, V and Shabala, SN and Davies, JM
Keywords: hydrogen peroxide, calcium, channel, root, epidermis.
Journal or Publication Title: The Plant Journal
Publisher: Blackwell Publishing Ltd.
ISSN: 0960-7412
DOI / ID Number:
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